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a USDA-ARS Western Wheat Quality Laboratory, Pullman, WA 99164-6394
b Dep. Crop & Soil Sciences, Pullman, WA
c Dep. Horticulture & Crop Sci., Agric. Univ. Norway, Ås, Norway
d Plant, Soil & Environmental Sciences Dep., Montana St. Univ., Bozeman, MT
e Dep. Agronomy & Plant Genetics, Univ. Minnesota, St. Paul, MN
Corresponding author (morrisc{at}wsu.edu)
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ABSTRACT |
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 TOPNOTES ABSTRACT INTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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Abbreviations: aka, also known as • bp, base pair • CI, cereal introduction • CItr, cereal introduction, Triticum • Da, Dalton • GRIN, Germplasm Resources Information Network • PCR, polymerase chain reaction • PI, plant introduction • PNW, Pacific Northwest • SDS-PAGE, sodium dodecylsulfate polyacrylamide gel electrophoresis • SKCS, Single Kernel Characterization System
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INTRODUCTION |
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TOPNOTESABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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The first insight into the molecular basis for kernel texture came with the discovery of friabilin. Friabilin, an Mr 15-kDa protein, is abundant on the surface of water-isolated soft wheat starch, scarce on the surface of hard wheat starch, and absent on durum (Triticum durum Desf.) (Greenwell and Schofield, 1986). Friabilin was found to be inherited additively according to Hardness allele dosage (abundant friabilin and soft kernel texture, HaHaHa, scarce friabilin and hard kernel texture, hahaha, and two intermediate levels of hardness and friabilin in heterozygous endosperm, HaHaha and Hahaha) (Bettge et al., 1995). The occurrence of friabilin was found to be mediated by bound polar lipids on the starch granule surface (Greenblatt et al., 1995). Morris et al. (1994) and Oda et al. (1992) later found that friabilin was actually more than one polypeptide. It is now well established that the main components of friabilin are, in fact, the Triton X-114 soluble proteins puroindolines a and b isolated by Blochet and co-workers (Blochet et al., 1991, 1993), and cloned and sequenced by Gautier et al. (1994) (Morris et al., 1994). The differential occurrence of friabilin on the surface of water-washed starch is apparently a partitioning phenomenon related to both the lipid binding properties of friabilin and the starch isolation procedure. Friabilin was shown to occur at roughly equivalent levels in both hard and soft wheat endosperm (Jolly et al., 1993). These apparently contradictory data were resolved with the discovery of two highly conserved hardness mutations in the puroindoline proteins (Giroux and Morris, 1997, 1998). The first puroindoline mutation that confers hardness is a null allele in puroindoline a, with no protein or mRNA transcript present (Pina-D1b) (Giroux and Morris, 1998) (Table 1). The second mutation is a single nucleotide base change in the codon of Gly–46, converting this amino acid to serine (Pinb-D1b) (Giroux and Morris, 1997). Two additional mutations in puroindoline b (Pinb-D1c and Pinb-D1d) were found during a survey of a large number of wheats of mostly Northern European origin (Lillemo and Morris, 2000). These two additional hardness mutations were both characterized as being single-nucleotide mutations and resulted in a change from Leu-60 to proline, and Trp-44 to arginine at these amino acid positions (Lillemo and Morris, 2000) (Table 1). Each puroindoline allele has been assigned a molecular marker designation (Table 1). The Pina-D1b allele was first characterized in the Australian cultivar Falcon and the Pinb-D1b allele was first characterized in the `Chinese Spring' substitution line possessing the 5D chromosomes of `Cheyenne' (Giroux and Morris, 1997, 1998). The Leu-60 to Pro-60 mutation was designated Pinb-D1c, and the second, Trp-44 to Arg-44, Pinb-D1d. The Arg-44 mutation was found in only three of 343 lines (Lillemo and Morris, 2000).
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MATERIALS AND METHODS |
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TOPNOTESABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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`Utac' was also grown in 1999 on experimental plots ("Barmore Research Farm") maintained by the Western Wheat Quality Laboratory in Pullman, WA, from seed obtained from the PNW Historical Nursery. Individual spikes were threshed and seed was analyzed by the SKCS and nucleic acid methods described below.
Grain hardness (kernel texture) was determined on an approximately 300-kernel subsample by the Perten Model SKCS 4100 Single Kernel Characterization System (Perten Instruments North America Inc., Springfield, IL). Although the SKCS data are not directly amenable to testing the significance of differences among cultivars because of lack of true replication, the very high level of expression of the hardness gene as measured by the SKCS qualitatively separates the soft and hard classes.
Protein Extraction and SDS-PAGE Detection of Puroindoline a Nulls
Triton-soluble proteins including puroindoline a and b were extracted from one to three crushed kernels with Triton X-114 detergent, separated by SDS-PAGE, and visually examined for the presence of puroindoline bands as described by Morris et al. (1994) and Giroux and Morris (1998).
DNA Isolation and Nucleic Acid-Based Detection of Puroindoline Alleles
Genomic DNA was isolated from each cultivar by the method of Dellaporta et al. (1983). Two tissues were used: leaf tissue from 10 to 15 plants each at the two- to three-leaf stage or individual half kernels (embryo half). The Pinb-D1a vs. Pinb-D1b allele alternatives (wild-type Gly-46 vs. the Ser-46 mutation) were assessed by means of sequence-specific primers which amplify allele-specific 250-bp fragments (Giroux and Morris, 1997). To assess the Pinb-D1c allele (Leu-60 to Pro-60), full length puroindoline b PCR product was restricted with PvuII after the method of Lillemo and Morris (2000). All PCR products were visualized on 1.5% (w/v) agarose gels. Full-length puroindoline a and b were amplified with the primers described by Gautier et al. (1994), isolated from agarose gels after electrophoresis and sequenced by means of the amplification primers.
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RESULTS |
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TOPNOTESABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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47 hardness. All these soft wheats exhibited a puroindoline a band on SDS-PAGE (summarized in Table 2, gel data not shown). Of the seven randomly selected soft wheat cultivars checked by means of the "soft" wild-type Gly-46 specific PCR primer, all showed a product. None of the cultivars produced a PCR product with the "hard" Ser-46 specific primer (Table 2).
Table 2 indicates the reference source for these soft (Class 5 and 4) cultivars. All but `Spinkcota', `Pitic 62', and `World Seeds 1' were described in Mercado et al. (1996). `Aka Komugi' (PI 45234, also CI 6138) is listed as `Akagomughi' by van Beuningen and Busch (1997), Mercado et al. (1996), and Borojevi
(1983). Spinkcota and Pitic 62 were listed by Miller et al. (1990) as hard red spring cultivars. Bayles and Clark (1954) described Spinkcota as having hard, red kernels. Seed from the NSGC exhibited the similar soft texture as observed with the seed from the PNW Historical Nursery (SKCS hardness = 37±17). The correct classification of this cultivar is unknown. Although Pitic 62 is also listed by Miller et al. (1990) as a hard red spring wheat, the presence of puroindoline a protein and absence of Ser-46 specific PCR product were all consistent with the SKCS soft texture phenotype. The original description of Pitic 62 (INIA and CIMMYT, 1972) describes the kernel as soft. World Seeds 1 was listed in the GRIN (http://www.ars-grin.gov/; verified August 9, 2000) and by Miller et al. (1990) as hard white spring, yet the SKCS data indicate that it is soft. Seed from both the PNW Historical Nursery and the NSGC were consistent in their soft character.
Ten spring wheat cultivars were classified as "mixed" (hardness Class 3 or 2, Table 2) by the SKCS. All Class 3 cultivars exhibited intermediate hardness values (44–59) and generally higher standard deviations (16–20). Six of the seven Class 2 cultivars had at least three-fourths of their kernels 47 and mean hardness values of 58-68.
Seed of Utac from the PNW Historical Nursery was classed as `3' with an SKCS hardness of 51±19 (data not shown). New seed obtained from NSGC was classed as `2' with an SKCS hardness of 49±13 (Table 2). Since none of these data provided a clear indication as to the homogeneity of this cultivar, new seed was propagated and individual spikes were analyzed for both hardness and puroindoline genotype. Individual spike data clearly revealed the hard and soft mixed nature of Utac. Of 8 spikes tested, 3 were classed as soft (Class 4 or 5) and 5 as hard (Class 1) (data not shown). Puroindoline a and b were sequenced from the hard component of Utac; the results revealed "wild-type" puroindoline a (Pina-D1a) but a previously unknown single-nucleotide mutation in puroindoline b (see Table 1). The point mutation causes Trp-44 to change to a stop codon (TGG to TGA). This allele was given the molecular marker designation, Pinb-D1f. Bayles and Clark (1954) described Utac as, "kernels white, semihard to hard" which would be consistent with a cultivar having a mixture of hard and soft kernels.
`Adams', `Wampum', `Henry', `Sawtell', `Kodiak Dwarf', and `Bronze Chief' were grown as part of the Historical Wheat study (Miller et al., 1990). New seed was obtained from NSGC and gave similar, mixed hard and soft SKCS results (data not shown). In all six of these mixed cultivars the "hard" component exhibited the prevalent Gly-46 to Ser-46 hardness mutation (Table 2). Adams is listed in its registration notice (Rohde, 1972) as a hard white spring derived from an F4 bulk of the cross `Idaed'/`Burt'. Idaed is a soft white spring and Burt a hard white winter, so it is possible that Adams was originally released as a hard and soft mixed (heterogeneous) cultivar. Adams and Burt share the Pinb-D1b hardness allele (Tables 2 and 3). Wampum was never registered. Henry is described by Bayles and Clark (1954) as "kernels semihard to hard" which is consistent with a hard and soft mixed composition. Sawtell has the pedigree `Sonora 64'/`Winalta'. Sonora 64 and Winalta are listed on the Greengenes server (see Materials and Methods) as hard red spring and winter cultivars, respectively. The source of the soft component of Sawtell is unknown. Sawtell was developed by Don Sunderman at Aberdeen, ID. Kodiak Dwarf and Bronze Chief share the same pedigree (`McKay'/`Plainsman V'). New seed of Kodiak Dwarf from NSGC produced an SKCS Class 3 ("mixed") with a hardness value of 60±21. Greengenes lists Plainsman V as a hard red winter cultivar. The source of the soft component of Kodiak Dwarf and Bronze Chief are unknown; both cultivars originated at Great Plains Seed and Research, Inc., Bozeman, MT.
Original seed of McKay from the PNW Historical Nursery produced a "mixed" (Class 2) SKCS hardness value of 68±18 with about 15% soft kernels (<47). New seed of McKay from NSGC produced an SKCS hardness of 82±17 (Table 2).
The remaining three mixed class spring wheat cultivars, `Kenya', `Kenya 324' and `Ladoga', were included due to their historical significance (Mercado et al., 1996). PCR results indicated that the "hard" component of Kenya possessed the Ser-46 Pinb-D1b allele (Table 2). A survey of four randomly-selected kernels of Kenya 324 produced only soft wild-type puroindoline b sequence. Regarding the "Kenya" cultivars it should be noted that over 10 accessions of "Kenya" exist in the NSGC.
The "hard" component of Ladoga exhibited puroindoline a protein on SDS-PAGE, produced no product using the Ser-46 specific PCR primer, but did exhibit the PvuII restriction site characteristic of the Leu-60 to Pro-60 hardness allele (Table 2). Sequencing full-length puroindoline a and b PCR products confirmed this genotype (Pina-D1a, Pinb-D1c).
The majority (n = 71) of the spring wheat cultivars included in the study proved to be hard (Class 1, Table 2). SKCS hardness ranged from 57 for `Mida' to 83 for `Aim'. All but `Red Egyptian', `Marroqui 588', ID377s, `Fife', `Hard Red Calcutta', and `Gehun' were included in the PNW Historical Wheat study and seed was obtained from Spillman Farm. Because `Red Fife' was listed by Miller et al. (1990) as a soft red spring, it was not originally included in the PNW Historical Wheat set, but was obtained later from NSGC.
Of these 71 Class 1 hard spring wheat cultivars, 18 were shown to lack puroindoline a protein (Table 2) and therefore carry the Pina-D1b hardness mutation. PCR results conducted using both the Gly-46 and Ser-46 specific primers were consistent with this genotype, that is, all expressed the "soft" wild-type Gly-46 puroindoline b sequence. A check of five randomly-selected cultivars lacked the Leu-60 to Pro-60 hardness mutation.
The majority of the hard spring wheat cultivars (n = 47) produced the characteristic 250-bp PCR fragment using the Ser-46 specific primer. These results along with the presence of puroindoline a protein on SDS-PAGE and the lack of PCR product using the Gly-46 specific primer were all consistent with the presence of the Pinb-D1b hardness allele in these cultivars (Table 2). Initially, it was difficult to obtain clear PCR results with `Canthatch' and `Red River 68'. They were checked for the Leu-60 to Pro-60 mutation, found not to have it, and eventually had puroindoline a and b sequenced in their entirety. This sequencing confirmed their Ser-46 Pinb-D1b hardness genotype.
Of the remaining six Class 1 hard spring wheats, four (Hard Red Calcutta, `Ruby', `Red Bobs', and `Supreme') exhibited the unique PvuII cleavage site in puroindoline b associated with the Leu-60 to Pro-60 mutation (Pinb-D1c allele, Table 1) (Lillemo and Morris, 2000). These cultivars additionally showed puroindoline a protein (SDS-PAGE), the soft Gly-46 PCR product, and no Ser-46 specific PCR product (Table 2).
The last two hard spring cultivars, Gehun and `Canadian Red', exhibited puroindoline a protein on SDS-PAGE, a Gly-46 specific PCR product, but no Ser-46 PCR product. New seed was obtained from NSGC and puroindoline a and b were sequenced. Both proved to have a single-nucleotide change in the codon of Trp-39 (TGG to TGA) which created a stop codon at this position. This hardness mutation was assigned the molecular marker designation, Pinb-D1e (Table 1).
Winter Wheats
Five winter wheats were shown to be soft by SKCS analysis (Class 5 or 4, Table 3); hardness values ranged from 19 to 38. All showed both puroindoline a and b proteins on SDS-PAGE, and no product using the Ser-46 specific PCR primer. As a control, `Benhur' and `Lucas' were checked using the Gly-46 specific primer and the characteristic 250-bp product was observed. Benhur and Lucas are described as soft red winter cultivars (Patterson et al., 1978; Heyne, 1960; respectively). `Gold Drop', `PI 178383', and `Sherman' were listed by Miller et al. (1990) as hard red winter cultivars. Although Gold Drop is also listed as a hard red winter wheat on the Greengenes web site, Clark (1927) lists it as a soft red winter wheat, as does GRIN which also describes kernel color as "white/amber," but gives no other indication as to kernel texture. Bayles and Clark (1954) describe Sherman as having "semihard" kernels, but go on to state, "Sherman differs from Turkey chiefly in having... softer kernels,..." Sherman is listed by Bayles and Clark (1954) as being derived from a cross involving `Turkey', `Budapest' and `Zimmerman'. Budapest appears in the GRIN as PI 11227 (inactive status, received 1904 from the Agricultural Experiment Station, Manhattan, KS). Its kernel texture is unknown. Zimmerman appears in GRIN as NSL34203, origin Oregon. Bayles and Clark (1954) describe this same Zimmerman as also known as `Oregon Zimmerman', and cautioned that, "It... should not be confused with the soft red winter cultivar bearing the latter [Zimmerman] name." Since Sherman originated at the Sherman Experiment Station in Oregon, it more likely involved the Oregon Zimmerman. Irrespective of which Zimmerman was indeed used in the cross to produce Sherman, a soft allele could have been inherited and present in the cultivar.
Only three winter wheat cultivars were classed as "mixed" by the SKCS (Class 2 or 3, Table 3). Of interest, both Turkey (aka `Turkey Red') and `Kharkof' were in this class. New seed was obtained from the NSGC and produced similar results (data not shown). Turkey had approximately 50% kernels 47 hardness, whereas in Kharkof, this percentage of hard kernels was only 23%. New NSGC seed of `Weston' was also classed as mixed. The hard and soft mixed nature of Turkey, Kharkof and Weston was unexpected. Bayles and Clark (1954) describe Turkey as having, "kernels red, midlong, hard,..." Their discussion of Kharkof does not indicate kernel texture. The GRIN lists Weston as being a hard red winter wheat derived from the cross `Bezostaya'/2/Burt/PI 178383. `Bezostaja' (PI 323468, the two spellings are considered equivalent) is listed in the GRIN as a hard red winter, Burt is a hard white winter (Heyne, 1959) and PI 178383 is a soft wheat (Table 3). Burt carries the Pinb-D1b allele (Table 3); Weston may have been released as a heterogeneous mixture of the soft allele from PI 178383 and the hard allele from Burt (or Bezostaja).
A significant number (ca. 17) of other winter wheat seed samples derived from the PNW Historical Nursery were characterized as being "mixed" (Class 2 or 3) (data not shown). These cultivars can be identified in Table 3 as having reference 1 (Miller et al., 1990), but having seed source listed as "G" (NSGC). In all cases, except the three cultivars just described as mixed, all new seed stocks from NSGC confirmed the uniformly hard (Class 1) phenotype (Table 3).
Nearly all (52 of 54) of the hard winter wheats (SKCS Class 1) (Table 3) produced a 250-bp product using the Ser-46 specific PCR primer, indicating that they possess the Pinb-D1b hardness allele. The majority were checked with the Gly-46 primer and none produced a product. Eight cultivars chosen at random were also checked on SDS-PAGE and were shown to express both puroindoline a and b proteins. These Pinb-D1b cultivars ranged in SKCS hardness from 56 (`Ute') to 84 (`Centurk'). `Warrior', `Scout', `Sturdy' and Centurk (Murphy et al., 1986) were added to the original set of PNW Historical wheats. The accession of `Triumph' was comprised of red and a minor proportion of white kernels, but both kernel color classes exhibited similar SKCS hardness (data not shown).
Two hard winter wheat cultivars, `Chiefkan' and `Andrews', failed to produce a product using the Ser-46 specific primers but did produce a product with the Gly-46 specific primers (Table 3). These two cultivars, then, did not possess the very prevalent Pinb-D1b hardness allele found in the majority (96%) of these North American hard winter wheat cultivars. Full-length puroindoline a and b PCR products were sequenced. Chiefkan proved to carry the Pinb-D1e allele previously observed in Canadian Red and Gehun hard spring wheat cultivars. Andrews was found to possess a single-nucleotide change (TGC to TGA) in the codon for Cys-56 which created a stop codon at this position. This Cys-56 to stop codon mutation was assigned the molecular marker designation Pinb-D1g (Table 1).
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DISCUSSION |
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TOPNOTESABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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In addition to those wheats considered to be of historical importance to the U.S. Pacific Northwest (Miller et al., 1990), an additional 13 spring and six winter wheats were included because of their prominent role in the development and parentage of North American wheat cultivars (Mercado et al., 1996; Murphy et al., 1986) (Tables 2 and 3). ID377s, Red Fife, and Bridger were added during the course of the study. Among the oldest cultivars included here are `Java' (introduction 1837) and Gold Drop (introduction 1843). Clark (1927) lists Java as a hard red spring, whereas Greengenes lists it as a soft red spring. Our data are consistent with the later classification. Conversely, Clark (1927) lists Gold Drop as a soft red winter, whereas Greengenes lists it as a hard red winter; in this case our data support the former description. Certainly, cultivars even older than these which are now mostly lost to history were the very earliest soft wheats brought from Europe during the initial stages of colonization (Jones, 1946). However, since these soft wheats represent the wild-type state of the Hardness gene, they are of limited use (except in an allelic sense) in studying the post-hexaploidation and domestication of wheat. If we accept the estimates that the hexaploidation event(s) were few and occurred not more than 9,000 years ago (Dvorak et al., 1998; Allaby et al., 1999), and also accept that the D-genome donor, Aegilops tauschii (Coss. [synonyms A. squarrosa, T. tauschii]) is uniformly soft in kernel texture, then we may conclude that all mutations in puroindoline proteins have arisen in the intervening period. Regardless of the evolutionary interest, the puroindoline hardness alleles serve to provide the means of analyzing ancestral relationships.
Among the earliest recorded introductions of spring wheats with hard kernel texture are Ladoga, Red Fife (aka Fife), Hard Red Calcutta, and Gehun (Table 2). Among these hard spring wheat cultivars, the "Fife series" is historically the most important. As related by Buller (1919), Red Fife was an inadvertent spring-habit selection from an otherwise winter-habit seed lot. The seed lot originated as a commercial sample of seed from Danzig (Gdansk) Galicia (Poland) and arrived in Ontario via Scotland about 1842. David Fife planted a portion of the seed in the spring and only one plant headed and matured. From this single plant, Red Fife originated and by the late 1880s dominated spring wheat production in Manitoba and Minnesota (Buller, 1919). Because of its popularity, Red Fife and selections thereof feature prominently in the early breeding work of Drs. William and Charles Saunders of the Dominion Experimental Farms. Further, the prevalence of the Pinb-D1b allele in hard spring wheats included here probably traces in large part to Red Fife and early cultivars derived from it, including Preston, Marquis, and later Thatcher. Marquis (and Thatcher) feature prominently in many North American hard spring wheat pedigrees.
Miller et al. (1990) listed White Fife and Red Fife cultivars, which were described as soft white spring and soft red spring, respectively. Consequently, neither of these cultivars were initially obtained from the PNW Historical Nursery. Mercado et al. (1996) listed Fife as a spring wheat and indicated its importance as having the largest total contribution (18.2%) to North American hard spring wheat cultivars. van Beuningen and Busch (1997) also highlighted the importance of Red Fife as an ancestor of North American spring wheat cultivars. A search of the GRIN database identified the Red Fife (PI 348919) and Fife (PI 283820) accessions included here (Table 2). Bayles and Clark (1954) described "Fife" as being another name for `Jones Fife'; however, they describe Jones Fife as a soft red winter cultivar, as does Miller et al. (1990). It seems likely that the Red Fife and Fife included here were derived from the same original introduction and may differ little. In this regard, variants of the original "Fife" described by Fraser and Whiteside (1956) would additionally include `Early Red Fife' (`Ottawa 16', C.A.N. 1288, a pure line selection from `Ordinary Red Fife'), Ordinary Red Fife, White Fife (listed as a parent of `Huron'), `Red Fife H' (aka `Type I c', a selection out of a common Red Fife), `Red Fife D' (listed as a parent of Ruby), and `White Russian' (C.A.N. 1567, aka `Wellman's Fife', a selection out of Red Fife).
Five spring wheats were shown to carry the Pinb-D1c hardness allele. Ladoga was introduced by W. Saunders, Dominion Cerealist, from Russia near Lake Ladoga in 1886 (Fraser and Whiteside, 1956). Although of mixed hardness, the hard component of Ladoga was shown here to carry the Pinb-D1c allele. Ladoga is present in the pedigrees of Preston (Ladoga x Red Fife) and several other early cultivars developed by W. Saunders (Fraser and Whiteside, 1956). Hard Red Calcutta was also imported by W. Saunders. As Buller (1919) pointed out, "Hard Red Calcutta,... is a commercial expression and includes several different types of wheat." The sample obtained from the NSGC (CI 015090) (Table 2) carries the Pinb-D1c hardness allele like Ladoga. Hard Red Calcutta was the female used to cross with Red Fife in the development of Marquis. Ruby also carries the Pinb-D1c allele (Table 2) so its lineage is of interest. According to Fraser and Whiteside (1956), Ruby resulted from the cross `Downy Riga' x Red Fife D made at Ottawa in 1905. Downy Riga is listed by Buller (1919) as resulting from the cross Gehun/`Onega'. Onega was introduced from northern Russia and is neither present in the NSGC nor listed on Greengenes. Gehun was found to possess a new allele and is dealt with in greater detail below. Although Downy Riga is not listed on Greengenes, a `Riga' cultivar (CItr 3317) appears on the GRIN (received 1912 from Agriculture Canada, Brandon, Manitoba). Greengenes lists the pedigree of `Garnet' as involving `Preston A'/`Riga M'. From this we may conclude that the Pinb-D1c allele of Ruby may have come from Onega.
Red Bobs and Supreme are the other two spring wheats exhibiting the Pinb-D1c allele (Table 2). According to Buller (1919) Red Bobs is most likely a natural out cross between `Bobs' and either Preston or Early Red Fife occurring at Seager Wheeler's farm in Saskatchewan. Macindoe and Brown (1968) describe Bobs as a selection from `Blount's Lambrigg' made by William Farrer in New South Wales in 1896. Surprisingly, Blount's Lambrigg originated from a hybrid made in the 1880s by Professor A.E. Blount in Colorado. And even though Greengenes indicates that Blount's Lambrigg (aka Gypsum) was a soft white wheat, the accession included here (Table 2) possesses a significant proportion of hard kernels such that Farrer could have easily selected hard types to produce Bobs. Supreme was a plant selection from Red Bobs made by S. Wheeler (Clark et al., 1927).
Even though the Pina-D1b allele was fairly prevalent among the hard spring wheats studied (Table 2), the origin of this allele is less certain. `Sea Island' is the oldest cultivar of this group. Greengenes lists it as "Probable Ladoga farmer selection." The different hardness alleles present in the accessions of Sea Island and Ladoga examined here would not support this description. The next oldest cultivar studied was `Komar'. Greengenes lists the pedigree of Komar as Marquis/`Kota'. Since Marquis carries the Pinb-D1b allele from Red Fife, Kota is the logical source of the Pina-D1b allele. Clark (1927) describes Kota as a hard red spring wheat, second only to Marquis in spring wheat acreage in 1924. Our data on seed obtained from NSGC (PI 192444) indicates Kota was soft. The discrepancy may lie in the identity of what really constitutes "Kota." Waldron and Clark (1919) describe the introduction of 25 samples of wheat from Russia by Prof. H.L. Bolley, one of which was approximately 75% durum and 25% common–the 25% subsequently being selected and named "Kota." The oldest accession of Kota in the NSGC is numbered CItr 5878 and described as being received from Montana St. Univ. in 1917. Analysis of this germplasm provided a SKCS hardness of 80±15 and a Pina-D1b puroindoline a genotype. The second accession of Kota in the NSGC, PI 192444 and the one used here, is listed as coming from Portugal in 1950. The third, PI 341423, is described as being collected from Turkey and was received in 1969. Clearly, in the context of ancestral lineages, CItr 5878 is the correct cultivar and likely represents the parent of Komar. Kota is then the oldest confirmed direct introduction of the Pina-D1b allele. `Ceres' having the same pedigree (Marquis/Kota) (Greengenes), carries the Pinb-D1b allele.
The last two Pina-D1b cultivars which were introduced to North America are Red Egyptian and Marroqui 588. Both are listed by Mercado et al. (1996) as featuring prominently in North American hard spring wheats but make no mention of the specific contribution. A cursory search of Greengenes revealed that Red Egyptian appears in the pedigree of RL 4205 which in turn appears in the pedigree of `Grandin', `Alex', `Butte 86', and `Len'. Although none of these cultivars were included here, Giroux and Morris (1998) showed that Butte 86 carried the Pina-D1b allele. The GRIN lists five accessions of "Red Egyptian." The oldest, CItr 12345 which was included here, came to the NSGC via Australia in 1944. Three (PI 45374, PI 45403, and PI 45415) came from South Africa in 1917. The fifth, PI 192020, came from Ethiopia via Italy in 1950. Our ability to establish ancestral lineage among these accessions and existing cultivars is poor.
Marroqui 588 (aka `Marroqui 588 Selection') is described by GRIN as being collected in Mexico in 1948 by the USDA. A search of GRIN for accessions with "Marroqui*" in their pedigree yielded 179 accessions, mostly numbered lines from CIMMYT. Of note, `Yaqui 50' has the pedigree `Newthatch' / Marroqui 588.
In our survey of spring wheat cultivars, two new hardness alleles were discovered. Gehun and Canadian Red shared a common point mutation in the codon of Trp-39 which created a stop codon. Fraser and Whiteside (1956) and Buller (1919) indicate that Gehun was introduced from India by W. Saunders and used in the cross that produced Prelude (`(downy) Gehun'/`Fraser', cross made in 1903) and in one of the parents of Ruby (Downy Riga/Red Fife D, cross made in 1905; Downy Riga = Gehun/Onega). The GRIN lists four Gehun accessions. The first three were collected in India, but from 1936 to 1948. The fourth accession was obtained from the Australian Winter Cereals Collection. The connection between these accessions and the Gehun used by Saunders is uncertain, but probably has no direct connection. Greengenes and the GRIN list Canadian Red as a hard white spring wheat from F.G. Stokes, Kelseyville, CA, of unknown pedigree, and released in 1919.
The last spring wheat of notable interest is Utac. The samples of Utac from both the PNW Historical Nursery and the NSGC were both shown to be mixed in kernel texture. The hard component was isolated and sequencing of puroindoline genes revealed that it possessed a new hardness allele, designated Pinb-D1f (Table 1). Similar to the Pinb-D1e allele, the Pinb-D1f allele is also a point mutation which creates a stop codon, in this case at position 44 which is only four bases away from the first hardness mutation characterized in puroindoline b, Pinb-D1b at position 46 (Giroux and Morris, 1997) (Table 1). This mutation occurs in the same codon as the apparently rare Pinb-D1d allele (Trp-44 to Arg-44, Table 1) (Lillemo and Morris, 2000). Bayles and Clark (1954) describe Utac as a club cultivar with, "kernels white, midlong, semihard to hard," which resulted from a cross between `Dicklow' and `Sevier' made about 1923 at the Utah Agricultural Experiment Station, Logan, UT. It was released in 1928. Dicklow is described by Greengenes and Bayles and Clark (1954) as a soft white spring wheat. Sevier (CItr 6247) was obtained from the NSGC, the puroindolines sequenced, and was found to carry the same Pinb-D1f allele. The origin of Sevier, a Utah landrace dating to about 1888, is provided by Stewart (1923).
As noted from Table 3, the hard winter wheats of North America mostly owe their hard kernel texture to Turkey, Kharkof, and other similar wheats referred to as the "Crimean Group" which were first introduced by immigrants to Kansas in 1873 (Bayles and Clark, 1954). Yet, surprisingly, the current accessions of Turkey and Kharkof are clearly mixtures of hard and soft alleles (Table 3). Whether these cultivars existed as such when first introduced or whether they became mixed through subsequent propagation is a matter of conjecture. Certainly as early as 1915, `Montana No. 36' and other such direct selections from Turkey were uniformly hard-kernel cultivars (as further example, Cheyenne was a single plant selection from `Crimean' made in 1922). As an aside, we can predict that the Pinb-D1b allele found in the mapping population involving `Clark's Cream' derived from Turkey wheat (Campbell et al., 1999).
The only hard winter wheat cultivars not carrying the Pinb-D1b allele were Chiefkan and Andrews (Table 3). Sequencing puroindoline a and b revealed that Chiefkan carries the same Pinb-D1e hardness allele as Canadian Red and Gehun (Table 1). Bayles and Clark (1954) list the pedigree of Chiefkan as `Blackhull'/soft wheat//`Superhard Blackhull'. `Kanhull', a sister selection to Chiefkan (Bayles and Clark, 1954), was not included in this study.
Andrews was the other hard winter wheat that did not possess the prevalent Pinb-D1b allele. Again, the puroindoline genes were sequenced and once more a point mutation which caused a stop codon in puroindoline b was found; in this case, at position Cys-56. The pedigree given for Andrews is PI 167822/CI 13438/2/CI 19342/`Itana'/3/CI 17271/Sturdy. `Itana 65' (and presumably, Itana) and Sturdy carry the Pinb-D1b allele (Table 3).
It will be of particular interest to those engaged in genetically improving wheat to learn to what extent the various puroindoline hardness alleles confer superior end-use quality. In this regard, the results of Giroux et al. (2000) and Martin et al. (2000) indicate that the Pinb-D1b allele confers significantly softer grain (Near-Infrared Reflectance and SKCS), higher milling break flour yields, and higher flour yields compared with the Pina-D1b allele. The production of near-isogenic lines involving all hardness alleles in a common genetic background would help advance this line of research.
In summary, the prevalence of puroindoline hardness alleles among North American wheat cultivars provides insight as to their ancestral lineage, a means of characterizing more fully their genome and highlights the relative greater diversity of hard spring wheat introductions as opposed to the hard winter wheats of the Great Plains, where Turkey, its descendants and closely related types account for the hard kernel texture of all but two cultivars examined. In this survey of wheat cultivars of historical importance, six different hardness alleles were encountered, three being previously unreported.
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ACKNOWLEDGMENTS |
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NOTES |
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TOPNOTESABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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Received for publication April 10, 2000.
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REFERENCES |
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TOPNOTESABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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, S. 1983. Genetic changes to increase yield potential in wheat. p. 953–957. In S. Sakamoto (ed.) Proc. Int. Wheat Genet. Symp., 6th, Kyoto. 28 Nov.–3 Dec. 1983. Plant Germ-Plasm Inst., Fac. Agric., Kyoto Univ., Kyoto, Japan.This article has been cited by other articles:
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  C. F. Morris and G. E. King Registration of Hard Kernel Puroindoline Allele Near-Isogenic Line Hexaploid Wheat Genetic Stocks Journal of Plant Registrations, January 1, 2008; 2(1): 67 - 68. [Full Text] [PDF]
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 W. Li, L. Huang, and B. S. Gill Recurrent Deletions of Puroindoline Genes at the Grain Hardness Locus in Four Independent Lineages of Polyploid Wheat1,[W],[OA] Plant Physiology, January 1, 2008; 146(1): 200 - 212. [Abstract] [Full Text] [PDF]
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 J. M. Martin, F. D. Meyer, C. F. Morris, and M. J. Giroux Pilot Scale Milling Characteristics of Transgenic Isolines of a Hard Wheat Over-Expressing Puroindolines Crop Sci., March 1, 2007; 47(2): 497 - 504. [Abstract] [Full Text] [PDF]
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H. W. Wanjugi, A. C. Hogg, J. M. Martin, and M. J. Giroux The Role of Puroindoline A and B Individually and in Combination on Grain Hardness and Starch Association Crop Sci., January 22, 2007; 47(1): 67 - 76. [Abstract] [Full Text] [PDF]
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C. G. Swan, F. D. Meyer, A. C. Hogg, J. M. Martin, and M. J. Giroux Puroindoline B Limits Binding of Puroindoline A to Starch and Grain Softness Crop Sci., June 20, 2006; 46(4): 1656 - 1665. [Abstract] [Full Text] [PDF]
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 C. G. Swan, J. G. P. Bowman, J. M. Martin, and M. J. Giroux Increased puroindoline levels slow ruminal digestion of wheat (Triticum aestivum L.) starch by cattle J Anim Sci, March 1, 2006; 84(3): 641 - 650. [Abstract] [Full Text] [PDF]
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A. C. Hogg, B. Beecher, J. M. Martin, F. Meyer, L. Talbert, S. Lanning, and M. J. Giroux Hard Wheat Milling and Bread Baking Traits Affected by the Seed-Specific Overexpression of Puroindolines Crop Sci., March 28, 2005; 45(3): 871 - 878. [Abstract] [Full Text] [PDF]
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G. Tranquilli, J. Heaton, O. Chicaiza, and J. Dubcovsky Substitutions and Deletions of Genes Related to Grain Hardness in Wheat and Their Effect on Grain Texture Crop Sci., November 1, 2002; 42(6): 1812 - 1817. [Abstract] [Full Text] [PDF]
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C.F. Morris and G.E. King Registration of Soft and Hard Red Winter Wheat Near-Isogenic Sister Lines of 'Weston' Crop Sci., November 1, 2002; 42(6): 2218 - 2219. [Full Text]
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C. F. Morris, G. E. King, R. E. Allan, and M. C. Simeone Identification and Characterization of Near-Isogenic Hard and Soft Hexaploid Wheats Crop Sci., January 1, 2001; 41(1): 211 - 217. [Abstract] [Full Text] [PDF]
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