Crop Science Journal of Natural Resources and Life Sciences Education
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

This Article
Right arrow Abstract Freely available
Right arrow Figures Only
Right arrow Full Text (PDF) Free
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in ISI Web of Science
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via ISI Web of Science (2)
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Zhang, J.F.
Right arrow Articles by Stewart, J.McD.
Right arrow Search for Related Content
PubMed
Right arrow Articles by Zhang, J.F.
Right arrow Articles by Stewart, J.McD.
Agricola
Right arrow Articles by Zhang, J.F.
Right arrow Articles by Stewart, J.McD.
Related Collections
Right arrow Cotton
Right arrow Crop Cytology
Right arrow Crop Genetics
Crop Science 41:283-288 (2001)
© 2001 Crop Science Society of America

CROP BREEDING, GENETICS & CYTOLOGY

CMS-D8 Restoration in Cotton Is Conditioned by One Dominant Gene

J.F. Zhang and J.McD. Stewart

Dep. of Crop, Soil and Environmental Sciences, Univ. of Arkansas, Fayetteville, AR 72701

Corresponding author (jstewart{at}uark.edu)


   ABSTRACT
TOP
 ABSTRACT
INTRODUCTION
 MATERIALS AND METHODS
 RESULTS AND DISCUSSION
 REFERENCES
 
Cytoplasmic male sterile (CMS-D8) and fertile restorer lines (D8R) of cotton (Gossypium hirsutum L.) (AD1) were developed by transferring the cytoplasm and nuclear gene(s) from G. trilobum (DC.) Skovst. (D8) into the cotton nuclear background. Understanding the genetics of fertility restoration in this CMS system is essential for its use in a hybrid breeding system. The objective of this investigation was to determine the mode of inheritance of D8R restoration to CMS-D8. The experimental approach involved a series of crossing schemes involving nuclear permutations among the AD1 and D8 alloplasms. Eighteen normal genotypes did not restore fertility to the CMS-D8 (A line) and could be used as maintainer (B) lines. D8R crossed as female with B lines yielded F1 and F2 populations with all fertile plants. F1 pollen also produced all fertile progeny in crosses on A lines. Thus, the D8 restorer functions at the gametophytic level. When heterozygous restored plants were pollinated with B lines, or when reciprocal F1's with normal cytoplasm were crossed as male with the A line, the progeny ratio was one fertile to one sterile. A 3:1 ratio was obtained when restored F1 plants with D8 cytoplasm were pollinated by their reciprocal F1's with normal cytoplasm. Accordingly, restoration of CMS-D8 by the D8R restorer is conditioned by a single dominant gene (Rf2). The genotypes for A, B, and D8R lines in the CMS-D8 system are designated S (rf2rf2), N (rf2rf2), and S (Rf2Rf2), respectively. This gametophytic restoration system is potentially useful for utilizing F2 heterosis in cotton.

Abbreviations: CMS, cytoplasmic male sterility • FCR, fluorochrome reaction


   INTRODUCTION
TOP
 ABSTRACT
 INTRODUCTION
MATERIALS AND METHODS
 RESULTS AND DISCUSSION
 REFERENCES
 
CYTOPLASMIC MALE STERILITY (CMS), a maternally inherited inability to produce functional pollen, is a very common phenomenon in higher plants (McVetty, 1997). Male fertility in CMS lines can be restored by introducing nuclear restorer gene(s). Because of this restoration ability, CMS has been successfully used in production of hybrid seeds in several field crops (McVetty, 1997).

Cytoplasmic male sterility can be found among natural or induced mutant populations, or induced by transferring exotic cytoplasms into cultivated species (Kaul, 1988). In upland cotton (Gossypium hirsutum L.), CMS was developed by introducing cytoplasms from diploid wild species into the cultivated tetraploid cottons. Cytoplasms from G. arboreum L. (A2) and G. anomalum Wawra ex Wawra & Peyritch (B1) in the upland cotton nuclear background produced partial male sterility (Meyer, 1969), while cytoplasm from G. harknessii Brandegee. (D2-2) in upland cotton (AD1) and G. barbadense L. (AD2) background induced complete male sterility (Meyer, 1975). An incompletely dominant restorer gene from G. harknessii was introgressed into cotton and shown to be linked to a mutant phenotype known as cracked root, Rc (Weaver and Weaver, 1977; Weaver and Weaver, 1979). In confirming the linkage between fertility restoration and cracked roots, da Silva et al. (1981) suggested that at least three dominant genes were involved in fertility restoration, with one of them being on chromosome 18D based on monosomic analysis. They also obtained evidence that modifying genes occurred on 16D, 25D, and telosomic 15L. However, Kohel et al. (1984) found only one dominant restorer gene, Rf, in CMS-D2-2 restoration, and found no linkage between Rf and 13 morphological markers distributed on at least nine chromosomes. Although extensive research has been conducted with the CMS-D2-2 system, very few hybrids with acceptable heterosis have been released for cotton production in the USA, China, India, and other main cotton-growing countries, mainly due to the significant yield reduction related to the D2 cytoplasm (Meyer, 1973; Weaver, 1986; Zhang et al., 1992; Sun et al., 1994; Basu, 1995).

Stewart (1992) developed a new CMS system, CMS-D8, based on the cytoplasm of G. trilobum (DC.) Skovst. Morphological characterization of CMS-D8 and cytological examination of sporogenous tissue abortion and restoration have been reported (Black and Stewart, 1995; Stewart, 1995; Stewart and Zhang, 1996; Stewart et al., 1996). The CMS-D8 A line had smaller corolla, pistil, calyx, style, and ovary, and fewer anthers compared with the maintainer (B) line. The sporogenous tissues of CMS-D8 anthers disintegrated before meiosis, while the heterozygous restored F1 showed normal microsporogenesis (Black and Stewart, 1995; Black, 1997). In a preliminary report (Stewart, 1995), the heterozygous F1 was found to produce 95 to 100% fertile progenies when self-pollinated or used as the male parent to cross onto CMS-D8. A cumulative ratio of one sterile to one fertile plant was obtained when bulked heterozygous restored plants were crossed as the female parent with a B line. However, different tests had widely different ratios. A large-scale genetic test showed that heterozygous F1 plants gave all fertile progenies when self-pollinated and produced progenies with a ratio of one sterile to one fertile when crossed as the female parent with normal cultivars in most cases (Stewart and Zhang, 1996; Stewart et al., 1996). A few unexpected segregants were attributed to incidental pollen or seed contamination. Although one dominant restorer gene was indicated in the past tests, additional data are required to determine whether the unexpected variants were, in fact, due to contamination or were a genetically determined result. The objective of this study was to determine the genetic control of D8R restoration in the CMS-D8 system of cotton.


   MATERIALS AND METHODS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
RESULTS AND DISCUSSION
 REFERENCES
 
Cytoplasmic male sterile lines, CMS-D8-8518 and CMS-D8-94, with ARK8518 and MDH 94 (Jenkins et al., 1984) nuclear background, respectively, were used as the female parent to cross and backcross with 12 upland cotton cultivars including Sure-Grow 125, 404, and 501; Stoneville 474 and 453; Deltapine 50; MD51ne (Meredith, 1993); Paymaster H1215 (Calhoun et al., 1997a), H1220 (Calhoun et al., 1997b), H1224 (Calhoun et al., 1997c), and H1277; and Acala 8610. Also crossed were six G. barbadense genotypes including Pima lines 76-4050 (Percy and Turcotte, 1997), 81-4442, and 8327-82-10 (Percy and Turcotte, 1993), 57-4, S-1, and 84514-9-3. All plants were grown in field plots on Captina silt loam (fine-silty, siliceous, active, mesic Typic Fragiudult) at Fayetteville, AR. The resulting F1, BC1F1, and BC2F1 plants from each cross with the fertile cultivars or breeding lines as pollen source were examined for male fertility (Fig. 1 , crossing scheme 1).



View larger version (11K):
[in this window]
[in a new window]
  		Fig. 1. Seven crossing schemes designed to determine the inheritance of the CMS-D8 restorer factor in cotton. Each specific crossing scheme is designated by a number in parentheses. (1) F1 and BC1 from crosses between CMS-D8 and AD1 or AD2. (2) F2 from D8R (as the female parent) by AD1. (3) Testcrosses (TC1) between (D8R x AD1)F1 as the female parent and AD1. (4) F2* from (D8R x AD1)F1 as the female parent crossed with the reciprocal F1. (5) Testcrosses (TC2) between CMS-D8 and (D8R x AD1) F1. (6) Testcrosses (TC3) between CMS-D8 and (AD1 x D8R) F1. (7) Testcrosses (TC4) between CMS-D8 and individual F2 plants from (AD1 x D8R)F1

 
Several restorer lines, originally designated D8R2, D8R3, and D8R5, were isolated when CMS-D8 was developed (Stewart, 1992). These lines, with D8 cytoplasm but male fertile, have been maintained by selfing each year. In 1995, two individual plants, G7-4 and G7-6, were chosen from D8R3 as the female parent for crosses with TM-1 (the genetic standard line in upland cotton), T-582 (a multiple recessive line), and T-586 (a multiple dominant line). For simplicity, we designate the homozygous D8 restorer lines as D8R, and normal upland cotton as AD1. The F1's of D8R x AD1 were grown in a greenhouse and scored for male fertility. Their reciprocal F1 crosses, that is, AD1 x D8R, were also made and grown at the same time. To verify the segregation of the restorer factor, 103 crosses in seven crossing schemes were made in 1996 and 1997 (Fig. 1).

Since the original D8R lines had complex background with substantial genetic contribution from G. trilobum, a program to develop improved D8R lines was initiated. One of the original D8R plants was crossed as the female parent with 8518, then the fertile heterozygous F1 plants were backcrossed as the female parent to 8518 in each generation. Male fertility was evaluated in BC4F1 and BC5F1 populations. The heterozygous fertile plants in the BC5F1 were also used as the female parent to cross with 15 additional genetic lines and cultivars including NC940088, NC940089, NC940142, NC94016, NC9401, NC940144; Sure-Grow 125, 404, and 501; Stoneville 453; MD51ne; DES 119 (Bridge, 1986); Deltapine 50; and Pima 84514-93 and 8327-82-10. The resulting populations were scored for male fertility in 1998 and were considered as variations of crossing scheme 3 (Fig. 1).

To further confirm the segregation ratios, 36 individual fertile plants from progenies with the 1:1 ratio of sterile to fertile plants from a composite cross, CMS-D8 x {8518 x [(CMS-D8 x D8R) x 8518]}, were used as the pollen source to cross with CMS-D8, while two of the fertile plants were crossed as the female parent with T-586. Single plant lineages were maintained when assessing fertility ratios.


   RESULTS AND DISCUSSION
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS AND DISCUSSION
REFERENCES
 
When two sterile A lines, CMS-D8-8518 and/or CMS-D8-94, were crossed with 12 upland cotton cultivars and six G. barbadense genotypes (crossing scheme 1), 1304 F1 plants from all but one cross were sterile (Table 1). The sterile plants were easily identified by the typical characteristics of CMS-D8 including small flowering buds and flowers with highly reduced stamen with no pollen production. The cross CMS-D8-8518 x Stoneville 474 had four fertile plants out of 69 F1 plants. However, no fertile plants were observed among 44 F1 plants from the cross CMS-D8-94 x Stoneville 474. The fertile plants probably resulted from seed or pollen contamination because no fertile plants were obtained in the first backcross (BC1) generation when the sterile plants from these two F1's were backcrossed with Stoneville 474. No fertile plants were observed in any other BC1 populations involving the other parental lines, nor were fertile plants obtained in BC2F1 from all the crosses. Thus, male sterility is conditioned by the D8 cytoplasm, and the restorer locus (non-restoring allele) from commercial cotton is unable to restore fertility. This result demonstrated that the selected commercial cotton cultivars have no restorer gene(s) and may be used as maintainer (B) lines of CMS-D8. Common tetraploid cotton might not contain any restorer factor(s) for the CMS-D8 system.


View this table:
[in this window]
[in a new window]
  		Table 1. Fertility and sterility in F1 of crosses of CMS-D8 x tetraploid cotton cultivars

 
In crossing scheme 2, the F1 and F2 of D8R x AD1 (i.e., TM-1, T-582, or T-586) and their reciprocals were all fertile (Table 2). Pollen production in F1 and F2 plants with the D8 cytoplasm appeared normal, showing little variation among plants. No obvious differences were present in flower size and pollen production between plants heterozygous and homozygous for the restoring factor, indicating that the restorer factor is completely dominant.


View this table:
[in this window]
[in a new window]
  		Table 2. Fertility in F2 progeny from reciprocal crosses between D8R and upland cotton

 
Since the D8R has D8 cytoplasm and is male fertile, it certainly carries the restorer factor. When it is used as the female parent to cross with AD1, the resulting F1's should be heterozygous for the restorer factor. Normally for a sporophytic restoration system, F1 plants would have 100% fertile pollen and their F2 population would consist of fertile and sterile plants. For example, a ratio of three fertile to one sterile would be observed in a one-locus model. On the contrary, in a gametophytic restoration system, a restored F1 would produce 50% viable pollen grains, called half-fertile, and no sterile plants would segregate in the F2 generation because the pollen grains with the non-restorer allele would not function in pollination. In the D8 system, the F1 seemed to have normal pollen production, as evidenced by pollen grain number and fluorochrome reaction (FCR) testing (Black, 1997), which suggested sporophytic restoration. Cytological observation of CMS-D8 also suggested that sterility resulted from sporophytic dysfunction in that degeneration of sporogenous tissues occurred before meiosis (Black, 1997). However, the nonsegregation of fertility in F2 suggested a gametophytic restoration system. The discrepancy between the cytological and genetic data led to speculation that nonviable pollen grains do exist in the restored heterozygous F1 plants, even though they could not be detected by the FCR test. When I2-KI was used to stain the pollen grains from the heterozygous restored F1, two types of pollen were distinguished. Approximately half of the pollen grains stained darkly and half stained lightly, while the normal cultivars and homozygous restorers had more than 98% dark-stained pollen.

To test the viability of the non-restorer allele with D8 cytoplasm in both male and female gametes, a series of testcrosses were made (Fig. 1, crossing schemes 3–6). F1 hybrids (between D8R as the female parent and 8518, TM-1, T-582, and T-586), which were heterozygous for restoration, were used as the female parent to cross with pollen sources not having the restorer factor (crossing scheme 3). All the testcrosses showed segregation in male fertility (Table 3). In a repeated backcrossing program in which the fertile plants were crossed as the female parent with 8518 as the recurrent pollen parent in each generation, fertility was scored in both BC4F1 and BC5F1 populations. Fertility was also scored when the fertile BC5F1 plants were crossed as the female parent with 15 different normal genotypes (Table 4). Genetically, these crosses can be considered as testcrosses. Assuming a one-gene-locus model, the segregation ratio of the crosses should be one fertile to one sterile. Applying the chi-square ({chi}2) test for goodness of fit to a 1:1 ratio, all the testcrosses showed no significant deviation from expectation. The result supports the conclusion that CMS-D8 restoration is controlled by one dominant restorer gene. It also indicates that both the restorer gene and its non-restorer allele in the D8 cytoplasm can be transmitted to the next generation through female gametes.


View this table:
[in this window]
[in a new window]
  		Table 3. Segregation of fertility in testcrosses (D8R x AD1)F1 x AD1 in cotton

 

View this table:
[in this window]
[in a new window]
  		Table 4. Fertility segregation when fertility-restored F1's with D8 cytoplasm were crossed as the female parent to normal cotton cultivars and breeding lines with AD1 cytoplasm

 
Three of four populations segregated sterile plants when F1's with the D8 cytoplasm were crossed as the female parent to their reciprocal F1's with AD1 cytoplasm (crossing scheme 4). The fourth population, consisting of only five plants, was fertile (Table 5). When the four crosses were combined, 38 fertile plants and 13 sterile plants fit a 3:1 segregation ratio as expected for a normal F2 population based on a one-locus model. This confirmed that both the restorer gene and its non-restorer allele in the AD1 cytoplasm function normally in microsporogenesis and microgametogenesis. Since the non-restorer allele is from the AD1 genome, it behaves normally in the AD1 cytoplasm, as expected.


View this table:
[in this window]
[in a new window]
  		Table 5. Fertility segregation in cotton crosses between alloplasmic F1's heterozygous for the D8R gene with the D8 alloplasm as the female parent and AD1 alloplasm as male parent

 
In contrast to the above results, when F1's with D8 cytoplasm were crossed as the male parent onto CMS-D8 (crossing scheme 5), all progenies were fertile (Table 6). In a similar study, when 36 heterozygous restored plants with D8 cytoplasm, derived from segregating populations with a ratio of one sterile to one fertile, were used to pollinate CMS-D8, the 36 families with a total of 2095 plants were all fertile (Table 7). However, when two of the 36 restored plants were crossed as the female parent with T-586, 20 fertile and 24 sterile plants were obtained (1:1 ratio, {chi}2 = 0.56), confirming heterozygosity for restorer in the two plants.


View this table:
[in this window]
[in a new window]
  		Table 6. Segregation of fertility in crosses between CMS-D8 and heterozygous restored F1's and their reciprocals in cotton

 

View this table:
[in this window]
[in a new window]
  		Table 7. Segregation of fertility in crosses involving heterozygous restored plants with D8 cytoplasm in cotton

 
All five crosses produced sterile and fertile plants in a 1:1 ratio (Table 6) when F1's with AD1 cytoplasm were crossed as the male parent onto CMS-D8 (crossing scheme 6). The combined populations comprised 225 sterile plants and 213 fertile plants (1:1 ratio, {chi}2 = 0.32). It is noteworthy that fertility segregation in the cross involving the tetraploid A2D8 gave a ratio of one fertile to one sterile. A2D8 is the synthetic tetraploid between G. arboreum (A2) and G. trilobum, the latter being the donor of the restorer gene for D8R. The data revealed that the D8 genome contains only one restorer gene that was transferred into the D8 restorer lines. In crossing scheme 7, 15 plants in the F2 population from the cross TM-1 x D8R were randomly selected to cross as the male parent with CMS-D8. Among their 15 progenies, 4 were all sterile, 5 were all fertile, and 6 indicated segregation for sterile and fertile plants. When testing against a 1 (homozygous restorer): 2 (heterozygous restored): 1 (homozygous non-restorer) ratio for goodness of fit, significant deviation was not detected ({chi}2 = 0.73; P = 0.50–0.70). The results clearly demonstrated that the restorer factor and its non-restorer allele segregate in a normal Mendelian manner in AD1 cytoplasm.

D8 cytoplasm induces male sterility when transferred into cultivated tetraploid cotton nuclear backgrounds. Therefore, the D8 cytoplasm in AD nuclear backgrounds is a male sterile cytoplasm, denoted as S, while the AD cytoplasm is denoted as N, representing normal cytoplasm. This genetic study clearly confirmed that restoration to CMS-D8 by the D8 restorer is controlled by a single dominant gene, and normal cotton cultivars do not have restorer genes. Kohel et al. (1984) assigned the symbol Rf to the D2-2 restorer factor of CMS-D2-2. Zhang and Stewart (2001) determined that the D8 restorer gene was not allelic to Rf and assigned Rf2 to the D8 restorer gene for the restoration of CMS-D8.

With the above designations, the genotypes for A, B, and R lines can be denoted as follows:

A line: S (rf2rf2)

B line: N (rf2rf2)

R line: S (Rf2Rf2)

The genetic data show that male gametes carrying the non-restorer allele from the AD genome in the D8 cytoplasm are nonfunctional and do not participate in fertilization. Thus, in crossing scheme 1, when CMS-D8 (i.e., A line) with the genotype S (rf2rf2) is crossed with normal cottons (AD1 or AD2) with the genotype N (rf2rf2), the resulting F1 has the genotype S (rf2rf2) and shows complete male sterility (Table 1). Repeated backcrossing with AD1 or AD2 can replace the nuclear genome with the recurrent parent, resulting in a new A line.

In crossing scheme 2, an R line with D8 cytoplasm and the restorer gene, that is, S (Rf2Rf2), is crossed as the female parent with a B line, N (rf2rf2), producing an F1 with heterozygous genotype S (Rf2rf2). The F1 produces two types of gametes, S (Rf2) and S (rf2), in both male and female. The two gametes as the female parent are both functional, while male gametes with S (rf2) with D8 cytoplasm are nonviable. This leaves only male gametes with genotype S (Rf2) to fertilize female gametes S (Rf2) and S (rf2), thereby producing all fertile F2 plants with 50% homozygous restored S (Rf2Rf2) and 50% heterozygous restored S (Rf2rf2) (Table 2). Similarly, in crossing scheme 5, male gametes S (Rf2) from the F1 fertilize the A line, S (rf2), giving all fertile heterozygous plants S (Rf2rf2) (Tables 6 and 7).

In crossing scheme 3, the two types of female gametes S (Rf2) and S (rf2) in the F1 are fertilized with normal gametes N (rf2) from the B line, producing 50% heterozygous fertile plants S (Rf2rf2) and 50% sterile plants S (rf2rf2) (Table 3). In subsequent backcrossing when the heterozygous fertile plants are used as the female parent to cross with the recurrent cotton cultivars, a one fertile to one sterile ratio is obtained in each backcross generation (Table 4). In crossing scheme 4, the two gametes, S (Rf2) and S (rf2) from the F1 (i.e., D8R x AD1) are fertilized with the two normal gametes N (Rf2) and N (rf2) from the reciprocal F1 with the genotype N (Rf2rf2), producing three fertile plants [one S (Rf2Rf2) and two S (Rf2rf2)] to one sterile plant [S (rf2rf2)]. A ratio of one fertile S (Rf2rf2) to 1 sterile S (rf2rf2) plant is produced (crossing scheme 6 and Table 6) when the two gametes from the reciprocal F1 are crossed with the A line. Upon self-pollination, the reciprocal F1 produces all fertile plants with the genotype constituents: one N (Rf2Rf2) and two N (Rf2rf2) to one N (rf2rf2). Among the progeny lines, 25% have all fertile plants and 25% have all sterile plants, while 50% of the progeny lines have a ratio of one fertile to one sterile plant (crossing scheme 7) when the individual F2 plants are crossed as the pollen source to the A line.

It is worthwhile to point out that since the original D8R lines were developed by plant selection from the same population as that for developing the CMS-D8, they may not be homozygous in restoration if the plant selections were not homozygous for the restored gene. In 1997, we found seven sterile plants among 79 F1 plants in a cross between D8R5 as the female parent and the MD51ne, indicating that at least some D8R5's were derived from a heterozygous plant. Since we subsequently determined that the two types of pollen grains in heterozygous restored plants can be differentiated by I2-KI staining, heterozygous restored plants can be detected and rogued by this method. Traditionally, homozygosity for restoration in selections for restorer lines is tested by using them as the male parent to cross with a CMS line, or as the female parent to cross with a B line. For practical purposes, the D8 restoration system has an advantage in that the development of a homozygous D8 restorer line is unnecessary, since the non-restorer allele in D8 cytoplasm cannot be transmitted via pollen.

Interestingly, both CMS-D8 and CMS-D2-2 are based on cytoplasms from D genome species. Both CMS systems share some similarities in that both male gametes abort before meiosis and have a reduced flower size. However, the restoration mechanisms are different in that D8 restoration is gametophytic while D2-2 restoration is sporophytic. Since no sterile plants occurred in F2 populations from crosses between A and R lines, the CMS-D8 restoration system offers a genetic means to feasibly utilize F2 heterosis (Meredith, 1990). The cost of seed for hybrid cotton production would be greatly reduced in this way. Gametophytic restoration also could facilitate double-cross seed production.

Our results also determined that the D2-2 restorer can restore CMS-D8, while the D8 restorer cannot restore CMS-D2-2 (Stewart, 1995). Zhang and Stewart (2001) reported that the D2R and D8R genes are not allelic but are closely linked. The two CMS and restoration systems need further investigation at the genetic, biochemical, and molecular levels to understand their mechanisms of action and their relation to each other.


   ACKNOWLEDGMENTS
 
We gratefully acknowledge the gift of seeds from Dr. E. Turcotte (Pima 76-4050, 81-4442, and 57-4), Dr. R.G. Percy (Pima S-1, 84514-9-3, and 8327-82-10), and Dr. D.T. Bowman (NC940088, NC940089, NC940142, NC94016, NC9401, and NC940144).

Received for publication March 3, 2000.


   REFERENCES
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS AND DISCUSSION
 REFERENCES
 




This article has been cited by other articles:


Home page
 Crop Sci.Home page
J. Zhang, J. M. Stewart, and T. Wang
Linkage Analysis between Gametophytic Restorer Rf2 Gene and Genetic Markers in Cotton
Crop Sci., January 1, 2005; 45(1): 147 - 156.
[Abstract] [Full Text] [PDF]

Home page
 Crop Sci.Home page
J. Zhang and J. McD. Stewart
Identification of Molecular Markers Linked to the Fertility Restorer Genes for CMS-D8 in Cotton
Crop Sci., July 1, 2004; 44(4): 1209 - 1217.
[Abstract] [Full Text] [PDF]

Home page
 Crop Sci.Home page
J.F. Zhang and J. McD. Stewart
Inheritance and Genetic Relationships of the D8 and D2-2 Restorer Genes for Cotton Cytoplasmic Male Sterility
Crop Sci., March 1, 2001; 41(2): 289 - 294.
[Abstract] [Full Text] [PDF]

This Article
Right arrow Abstract Freely available
Right arrow Figures Only
Right arrow Full Text (PDF) Free
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in ISI Web of Science
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via ISI Web of Science (2)
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Zhang, J.F.
Right arrow Articles by Stewart, J.McD.
Right arrow Search for Related Content
PubMed
Right arrow Articles by Zhang, J.F.
Right arrow Articles by Stewart, J.McD.
Agricola
Right arrow Articles by Zhang, J.F.
Right arrow Articles by Stewart, J.McD.
Related Collections
Right arrow Cotton
Right arrow Crop Cytology
Right arrow Crop Genetics

HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
The SCI Journals Agronomy Journal Vadose Zone Journal
Journal of Natural Resources
and Life Sciences Education		 Soil Science Society of America Journal
Journal of Plant Registrations Journal of
Environmental Quality		 The Plant Genome