HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Abstract Full Text (PDF) Free Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in ISI Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (2) Citing Articles via Google Scholar Google Scholar Articles by Mornhinweg, D. W. Articles by Webster, J. A. Search for Related Content PubMed Articles by Mornhinweg, D. W. Articles by Webster, J. A. Agricola Articles by Mornhinweg, D. W. Articles by Webster, J. A. Related Collections Crop Genetics Other Grain Crops Plant Genetic Resources

CROP BREEDING, GENETICS & CYTOLOGY

Inheritance of Russian Wheat Aphid Resistance in Spring Barley Germplasm Line STARS-9577B

USDA-ARS, 1301 N. Western Rd., Stillwater, OK 74075-2714

* Corresponding author (dmornhinweg{at}pswcrl.ars.usda.gov)

	ABSTRACT

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS NOTES RESULTS AND DISCUSSION REFERENCES

 
The Russian wheat aphid (RWA), Diuraphis noxia (Mordvilko), has become a major pest of barley (Hordeum vulgare L.) in the western USA. STARS-9577B (PI 591617), a six-rowed, spring barley germplasm line with a high level of resistance to RWA, was recently released to barley breeders for barley improvement. Understanding the inheritance of RWA resistance in this germplasm line is necessary for breeders to develop an effective strategy for utilization of this germplasm in their breeding programs. This greenhouse study was conducted to determine the genetic control of RWA resistance in STARS-9577B. Crosses were made between ‘Morex’, a susceptible, six-rowed, malting barley cultivar, and STARS-9577B. Genetic analyses were performed on reaction to RWA of parents, F₁, reciprocal F₁, F₂, backcrosses (BC₁F₁) to both parents, and F₂-derived F₃ families. Reaction was based on a visual rating scale of 1 to 9 (1 = no damage, 9 = dead plant). Segregation in the F₂ and BC₁F₁ populations indicated multiple gene control. Seventy-seven F₃ families were found to be homozygous resistant and 18 homozygous susceptible, indicating two gene control of RWA resistance in STARS-9577B. Analysis of data from F₂ and BC₁F₁ populations suggested RWA resistance in STARS-9577B is controlled by dominant alleles at two loci, with alleles at one locus conferring a high level of resistance and alleles at the other locus conferring an intermediate level of resistance only when recessive alleles are present at the first locus.

	INTRODUCTION

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS NOTES RESULTS AND DISCUSSION REFERENCES

 
IN NORTH AMERICA, the Russian wheat aphid, greenbug [Schizaphis graminum (Rondani)], and the bird cherry-oat aphid [Rhopalosiphum padi (L.)] are considered the most serious aphid pests of small grains (Porter et al., 1999). RWA is a devastating pest on barley grown in the intermountain regions of the western USA. RWA, first found in the USA in West Texas in 1986, now threatens wheat (Triticum aestivum L.) and barley production throughout the western USA. Economic loss from RWA in the western USA for the period 1987 to 1998 has been estimated over $1000 million (Porter et al., 1999). For barley, in 1992 alone there were 0.7 million hectares infested with RWA, which resulted in a loss of $18.5 million (Legg and Amosson, 1993). All barley cultivars presently in commercial production are susceptible to RWA feeding damage. Typical RWA feeding damage to the leaf results in characteristic longitudinal white, yellow, or red streaks with convolute rolling of the leaf. Leaf rolling reduces photosynthetic area, provides an optimum environment for aphid reproduction, protects aphids from contact insecticides and natural predators, and, at the heading stage, can prevent spike extrusion and decrease seed set (Mornhinweg et al., 1993).

A damage rating scale for wheat and barley seedlings was developed by Webster et al. (1991) based on visual rating of leaf chlorosis, leaf streaking, and leaf spotting. This visual rating was on a scale of 1 to 9 (1 = no damage, to 9 = dead plant). The amount of leaf rolling (1 = no rolling to 3 = completely rolled) was also noted. This scale was used to evaluate RWA resistance of all available barley accessions (23070) in the USDA National Small Grains Collection. One hundred-nine accessions, all originating from outside the USA, were identified with some level of resistance at the seedling stage. Homozygous pure lines selections were made from each accession (Mornhinweg et al., 1996).

Nkongolo et al. (1991) reported RWA resistance in wheat accession PI 372129 to be controlled by a single dominant gene. Baker et al. (1992) reported RWA resistance in wheat accession PI 149898 to be under the control of two genes (one dominant, one incompletely dominant). Robinson et al. (1992) reported a single dominant gene for RWA resistance in barley line S13. Nieto-Lopez and Blake (1994) analyzed the inheritance of RWA resistance in two barley accessions (PI 366444 and PI 366453) and determined there were at least two resistance genes in each accession. Genetic analysis of resistance in STARS-9301B (PI 573080), the first RWA-resistant barley germplasm line released (Mornhinweg et al., 1995a), indicated control of RWA resistance by alleles at two loci, Rdn1 and Rdn2, originally designated as Dnb1 and Dnb2 (Mornhinweg et al., 1995b). Specifically, expression of RWA resistance in STARS-9301B involves recessive epistasis of the dominant gene Rdn2 on the incompletely dominant gene Rdn1 (Mornhinweg et al., 1995b). Although this resistance is excellent, multiple gene inheritance in STARS-9301B would make the utilization of this germplasm line in a barley breeding program somewhat complicated. The search continues for a barley germplasm line with a high level of resistance to RWA and a simple inheritance pattern, such a line would be preferred by breeders over this more complicated inheritance. A second barley germplasm line, STARS-9577B (PI 591617), has been released (Mornhinweg et al., 1999). STARS-9577B, a RWA-resistant selection from CIho 4165, is an excellent source of resistance to the RWA, but little is known of the genetic control of this resistance. The objective of our study was to determine the inheritance of RWA resistance in STARS-9577B.

	MATERIALS AND METHODS

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS NOTES RESULTS AND DISCUSSION REFERENCES

 
Parents, F₁, F₂, and BC F₁s
Fourteen seeds each of Morex, STARS-9577B, Morex/STARS 9577B, and reciprocal F₁, 200 F₂ seeds, and 150 seeds of the BC₁F₁ to each parent (300 total) were planted into wet fritted clay (sieved through a 2- by 1-mm mesh screen) in Cone-tainers (Ray Leach Supercells, Stuewe and Sons, Inc, Corvallis, OR)¹ in the greenhouse in January of 1995. The experiment was conducted in two sowings, 2 d apart, with equal numbers of parents, F₁, and reciprocal F₁ at each sowing. The first sowing also contained the F2 while the second sowing contained both BC₁F₁ populations. Individual seedlings were caged upon emergence, and Cone-tainers were placed in racks in a randomized complete block design for each sowing. The racks were placed in metal trays (6 cm deep) containing water and fertilizer [Peter's 15-30-15 (5.29 g L^-1 water), Grace-Sierra Horticultural Products Co., Milpitas, CA]. Each seedling was infested with 10, 5-d-old RWA nymphs when plants were 3 to 5 cm in height (approximately 6 d after planting). Twelve hours of supplemental lighting was provided by two sodium metal halide lamps. RWA damage ratings were recorded 23 d after infestation when the first susceptible (Morex) seedling died. The seedlings were scored for chlorosis by the 1-to-9 scale described previously (Webster et al., 1991).

F₂-Derived F₃ Families
Three hundred individual F₂ plants from the cross Morex/STARS-9577B were grown and harvested individually in the spring of 1993. Thirty F₃ progenies from each plant (F_2:3 families) were sown in rows in screening flats in the greenhouse in January 1995. Each flat contained six F_2:3 rows and four rows of checks such that each F_2:3 family was adjacent to one check row. Each check row contained seed from both parents alternating every five seeds with each parent set represented in each check row three times. Seedlings in each flat were infested upon emergence (approximately 6 d after planting) by laying leaves of RWA-infested ‘Wintermalt’ barley from infested culture plants between each row. Seedlings were rated when all Morex check plants in the flat were dead, approximately 3 wk after infestation. Each seedling in each F_2:3 family was rated by a 1-to-9 scale (Webster et al., 1991).

Statistical Analysis
Genetic hypotheses were tested by ² analysis, with RWA resistance classes determined by the range of the parents and with rejection at the 0.01 level of probability.

	RESULTS AND DISCUSSION

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS NOTES RESULTS AND DISCUSSION REFERENCES

 
Visual RWA damage ratings of the F₁ and reciprocal F₁ were identical, indicating no maternal inheritance for RWA resistance in STARS-9577B. On the basis of this observation, the F₁ and reciprocal F₁ were pooled. RWA damage ratings for Morex, STARS-9577B, F₁, F₂, and BC₁F₁ to each parent are shown in Table 1 . Morex ranged in RWA rating from 5 to 9. All STARS-9577B rated 2 and all F₁ were identical to the resistant parent indicating complete dominance of RWA resistance in STARS-9577B. However, segregation in the F₂ was continuous (Table 1). When classes were grouped by the range of the resistant and susceptible parents (i.e., a RWA damage rating of 2 is resistant, ratings of 3 to 4 are intermediate, and ratings of 5 to 9 are susceptible), the ² analysis for goodness-of-fit of segregation in the F₂ to single gene ratios (Table 2) resulted in the rejection of single gene hypotheses. Further, if genetic control of RWA resistance in STARS-9577B was under the control of a single dominant gene, segregation in the BC₁F₁ to the susceptible parent should fit a genetic ratio of 1R: 1S with no intermediate individuals. The segregation pattern in the BC₁F₁ to the susceptible parent, Morex, (Table 1) was a continuous distribution with large numbers of intermediate individuals. RWA damage ratings of the BC₁F₁ progeny did not support the hypothesis of single gene control of RWA resistance.

View this table: [in this window] [in a new window]   Table 2. 2 goodness of fit of segregation in the F2 to single gene models.

Segregation in the F₂ indicated the existence of F₂ individuals that were intermediate to the parental ranges for resistance and susceptibility (Table 1). ² Analysis of RWA damage ratings, on the basis of several possible two gene inheritance models in the F₂ involving intermediate classes (Table 3) , indicated acceptability of only one segregation ratio, 12R: 3I: 1S, where R = resistant (rating of 2 like the resistant parent), I = intermediate (rating of 3 to 4), and S = susceptible (rating of 5 to 9 the range of the susceptible parent). This ratio would suggest that two dominant genes control resistance, with dominant epistasis of RWA resistant alleles at one locus masking expression of alleles at the second locus. With this model, the expected ratio of BC₁F₁ to the susceptible parent would be 2R: 1I: 1S while BC₁F₁ to the resistant parent should all be resistant. Analysis of the BC to Morex showed an acceptable fit for this ratio (Table 4) and all BC₁F₁ to STARS-9577B were resistant. Thus, RWA reaction data from the F₂ and both BC₁F₁ suggest that dominant alleles at two loci control RWA resistance in STARS-9577B and that resistance at one locus is expressed only when recessive alleles are present at the other locus.

View this table: [in this window] [in a new window]   Table 3. 2 goodness of fit of F2 to two-gene models.

View this table: [in this window] [in a new window]   Table 4. 2 goodness of fit of segregation in BC1F1 to two-gene models that give 12:3:1 segregation in the F2.

	NOTES

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS NOTES RESULTS AND DISCUSSION REFERENCES

 
¹ Mention of a proprietary product does not constitute a guarantee or warranty by the USDA, and does not imply its approval to the exclusion of other products that may also be suitable.

Received for publication November 26, 2001.

	REFERENCES

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS NOTES RESULTS AND DISCUSSION REFERENCES

 

• Baker, C.A., D.R. Porter, and J.A. Webster. 1992. Inheritance of Russian wheat aphid resistance in a winter wheat, PI 14989. p. 89. In Agronomy abstracts. ASA, Madison, WI.
• Legg, D., and S. Amosson. 1993. Economic impact of the Russian wheat aphid in the western United States: 1991-1992. Great Plains Agric. Council Publ. No. 147.
• Mornhinweg, D.W., D.R. Porter, and J.A. Webster. 1999. Registration of STARS-9577B Russian wheat aphid resistant barley germplasm. Crop Sci. 39:882–883.[Free Full Text]
• Mornhinweg, D.W., D.R. Porter, and J.A. Webster. 1996. Genetic diversity for Russian wheat aphid resistance in USDA-ARS barley germplasm lines. Barley Genet. Newsl. 27:7.
• Mornhinweg, D.W., D.R. Porter, and J.A. Webster. 1995a. Registration of STARS-9301B Russian wheat aphid resistant barley germplasm. Crop Sci. 35:602.[Free Full Text]
• Mornhinweg, D.W., D.R. Porter, and J.A. Webster. 1995b. Inheritance of Russian wheat aphid resistance in spring barley. Crop Sci. 35:1368–1371.[Abstract/Free Full Text]
• Mornhinweg, D.W., D.R. Porter, and J.A. Webster. 1993. Inheritance of Russian wheat aphid resistance in spring barley germplasm line STARS-9301B. Barley Genet. Newsl. 23:40.
• Nieto-Lopez, R.M., and T.K. Blake. 1994. Russian wheat aphid resistance in barley: Inheritance and linked molecular markers. Crop Sci. 34:655–659.[Abstract/Free Full Text]
• Nkongolo, K.K., J.S. Quick, F.B. Peairs, and W.L. Meyer. 1991. Inheritance of resistance of PI 372129 wheat to the Russian wheat aphid. Crop Sci. 31:905–907.[Abstract/Free Full Text]
• Porter, D.R., D.W. Mornhinweg, and J.A. Webster. 1999. Insect resistance in barley germplasm. p. 51–61. In S.L. Clement and S.S. Quisenberry (ed.) Global plant genetic resources for insect-resistant crops. CRC Press, Inc., Boca Raton, FL.
• Robinson, J., P.A. Burnett, H.E. Vivar, and F. Delgado. 1992. Russian wheat aphid in barley: Inheritance of resistance and yield loss. p. 94–97. In W.P. Morrison (comp.) Proceedings of the 5th Russian Wheat Aphid Conference. Great Plains Agric. Counc. Publ. 142.
• Webster, J.A., C.A. Baker, and D.R. Porter. 1991. Detection and mechanisms of Russian wheat aphid (Homoptera:Aphididae) resistance in barley. J. Econ. Entomol. 84:669–673.

This article has been cited by other articles:

				S. Mittal, L. S. Dahleen, and D. Mornhinweg Locations of Quantitative Trait Loci Conferring Russian Wheat Aphid Resistance in Barley Germplasm STARS-9301B Crop Sci., July 1, 2008; 48(4): 1452 - 1458. [Abstract] [Full Text] [PDF]

				P. Bregitzer, D. W. Mornhinweg, D. E. Obert, and J. Windes Registration of 'RWA 1758' Russian Wheat Aphid-Resistant Spring Barley Journal of Plant Registrations, January 1, 2008; 2(1): 5 - 9. [Abstract] [Full Text] [PDF]

				P. Bregitzer, D. W. Mornhinweg, and B. L. Jones Resistance to Russian Wheat Aphid Damage Derived from STARS 9301B Protects Agronomic Performance and Malting Quality When Transferred to Adapted Barley Germplasm Crop Sci., November 1, 2003; 43(6): 2050 - 2057. [Abstract] [Full Text] [PDF]

This Article Abstract Full Text (PDF) Free Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in ISI Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (2) Citing Articles via Google Scholar Google Scholar Articles by Mornhinweg, D. W. Articles by Webster, J. A. Search for Related Content PubMed Articles by Mornhinweg, D. W. Articles by Webster, J. A. Agricola Articles by Mornhinweg, D. W. Articles by Webster, J. A. Related Collections Crop Genetics Other Grain Crops Plant Genetic Resources