Cytoplasmic-nuclear Male-sterile Line Research Articles

Key biological factors related to outcrossing-productivity of cytoplasmic-nuclear male-sterile lines in soybean [Glycine max (L.) Merr.

Soybean scientists in China have tried to utilize heterosis for yield enhancement. A number of cytoplasmic-nuclear male-sterile (CMS) lines, their maintainers and restorers were developed, but the commercialized hybrid seed production is still a bottleneck. Five soybean CMS lines with their maintainers and restorers were studied for the sufficiency of viable and effective pollens from maintainers/restorers, the natural insect pollinators in fields and outcrossing capacity of CMS lines. The results showed that the maintainers/restorers may offer viable pollens during the flowering day time in Nanjing and Taiyuan (germination rate 77.8–86.5%). But the morning dew causes pollens losing effectiveness in Nanjing, while normal in Taiyuan, indicating the location and planting season without morning dew is a key for CMS/hybrid seed production. In CMS fields in Taiyuan, the major insect pollinators composed of China bee (54.3%), Mellifera bee (11.3%), Northern-cutting bee (6.0%), Corn belt hair bee (1.5%), etc. A parallel trend between insect number and flower nectar amount in a day with peak time at 12:00–13:00 implied the soybean nectar attracting the insects. The outcrossing pod-set rate of CMS lines in net-room with artificial-raised bees, net-room without bees and open-field with enhanced natural insects was 57.8, 2.1 and 47.3%, respectively, indicating that insect pollination is necessary. The realized outcrossing pod-set rate in seed production field achieved 88.9% (1460.4 kg/ha) for SXJLCMS1A × SXJLCMS1B and 145.2% (1829.5 kg/ha) for SXCMS1A × JY-31, different outcrossing capacity existed among CMS lines. Thus the CMS/hybrid seed production can be improved through optimizing the pollen effectiveness, pollinator population and talented CMS line.

Identification of dominant and recessive genes for resistance to Fusarium wilt in pigeonpea and their implication in breeding hybrids

Fusarium wilt is an important disease of pigeonpea [Cajanus cajan (L.) Millsp.] and it can cause severe yield losses. Chemical control of this disease is difficult and expensive; therefore, cultivation of resistant varieties/hybrids is the most efficient strategy for enhancing the production. In the present study, by using a wilt susceptible cytoplasmic-nuclear male-sterile line and four wilt resistant fertility restorers, one dominant and one recessive gene with dominant suppressive epistatic effects were found responsible for controlling resistance to Fusarium wilt. Considering the annual losses and wide spread nature of wilt diseases in pigeonpea, it is imperative that all the inbred and hybrid cultivars have high level of resistance to this disease. The presence of dominant gene for resistance will increase the efficiency of breeding wilt resistant cultivars because it will yield greater proportion of resistant genotypes in segregating generations. In hybrid breeding also, the presence of dominant gene for wilt resistance will be an advantage. The transfer of this gene in female hybrid parents will ease the breeding of wilt resistant hybrids because this will allow the use of both wilt resistant as well as susceptible restorers in generating wilt resistant hybrid combinations.

RAPD Analysis on Variation of Mitochondrial DNA for Cytoplasmic-Nuclear Male Sterile Lines in Wheat

In order to produce a good F1 hybrid variety in wheat, it is necessary to explore a new male-sterile cytoplasm and its nuclear restore gene(s). Four alloplasmic male sterile lines of wheat with Aegilops cytoplasm were developed to identify mitochondrial DNA (mtDNA) variation that could potentially be associated with cytoplasmic male sterility (CMS). mtDNA isolated from the Aegilops species, the respective male sterile lines and F1 hybrids were analyzed by RAPD markers. Reproducible polymorphisms were detected between the Aegilops species and male sterile lines. Above results indicated that mtDNA variation existed in the cytoplasm donors and male sterile lines resulted from genetic interactions between common wheat nucleus and Aegilops cytoplasm, and have affected the structure of the mitochondrial genome. Similar results were also obtained in male sterile lines and fertility-restored F1 hybrids. These demonstrated the variation of mtDNA in fertility restoration by the combination of the fertility restorer gene(s), and fertility restoration involved a strong influence of nuclear restorer genes on mtDNA organization. The variation of mtDNA in Aegilops species, their respective CMS lines and fertility-restored F1 hybrids may reflect the fertility divergence.

Fertility Restoration in Cytoplasmic-Nuclear Male-Sterile Lines Derived from 3 Wild Relatives of Pigeonpea

Three cytoplasmic-nuclear male-sterile (CMS) lines, one each derived from Cajanus sericeus (A(1) cytoplasm), Cajanus scarabaeoides (A(2) cytoplasm), and Cajanus cajanifolius (A(4) cytoplasm), were crossed to 7 pigeonpea (Cajanus cajan (L.) Millsp.) cultivars in a line x tester mating scheme to study the fertility restoration of the CMS lines. Twenty-one F(1) hybrid combinations were planted in unreplicated 3-row plots in 3 environments. There was no effect of environments on the expression of fertility restoration. Pigeonpea cultivar ICPL 129-3 restored fertility in A(1) cytoplasm and maintained male sterility in the other 2 (A(2) and A(4)) cytoplasms. Among crosses involving CMS line (of A(4) cytoplasm) ICPA 2039 one hybrid combination was male-sterile and another male fertile. The remaining 5 combinations segregated for male-fertility (66-84% fertility restoration). Such testers can easily be purified for use in hybrid breeding programs by selfing and single-plant selection for 2-3 generations.

Discovery of new male-sterile cytoplasm sources and development of a new cytoplasmic-nuclear male-sterile line NJCMS3A in soybean

Most of the cytoplasmic-nuclear male-sterile (CMS) lines of soybean were developed only from a limited cytoplasm sources and performed not as good as required in hybrid seed production, therefore, to explore new male-sterile cytoplasm sources should be one of the effective ways to improve the pollination and hybridization for a better pod-set in utilization of heterosis of soybeans. In the present study, total 80 crosses between 70 cultivated and annual wild soybean accessions and three maintainers (N2899, N21249, and N23998) of NJCMS1A were made for detecting potential new sources with male-sterile cytoplasm. The results showed that in addition to the crosses with N8855.1 (the cytoplasm donor parent of NJCMS1A) and its derived line NG99-893 as cytoplasm parent, there appeared three crosses, including N21566 × N21249 and N23168 × N21249, with male-sterile plants in their progenies. According to the male fertility performance of backcrosses and reciprocal crosses with the tester N21249, the landrace N21566 and annual wild soybean accession N23168 were further confirmed to have male-sterile cytoplasm. Accordingly, it was understood that the source with male-sterile cytoplasm in soybean gene pool might be not occasional. The results also showed that the genetic system of male sterility of the newly found cytoplasm source N21566 was different from the old cytoplasm source N8855.1, while N23168 was to be further studied. Based on the above results, the derived male-sterile plants from [(N21566 × N21249) F1 × N21249] BC1F1 were back-crossed with the recurrent parent N21249 for five successive times, and a new CMS line and its maintainer line, designated as NJCMS3A and NJCMS3B, respectively, were obtained. NJCMS3A had normal female fertility and stable male sterility. Its microspore abortion was mainly at middle uninucleate stage, earlier than that of NJCMS1A and NJCMS2A. The male fertility of F1s between NJCMS3A and 20 pollen parents showed that 7 accessions could restore its male fertility and other 13 could maintain its male sterility. The male sterility of NJCMS3A and its restoration were controlled by one pair of gametophyte male-sterile gene according to male fertility segregation of crosses between NJCMS3A and three restorers. The nuclear gene(s) of male sterility in NJCMS3A appeared different from the previously reported CMS lines, NJCMS1A and NJCMS2A. The development of NJCMS3A demonstrated the feasibility to discover new CMS system through choosing maintainers with suitable nuclear background.

Inheritance of male fertility restoration of the cytoplasmic-nuclear male-sterile line NJCMS1A of soybean [Glycine max (L) Merr.

At present, no report on inheritance of male fertility restoration has been released, yet more than 10 cytoplasmic-nuclear male-sterile soybean lines as well as their maintainers and restorers have been developed. Based on our previous work, 25 restorers for the male-sterile line NJCMS1A were identified and the inheritance of male fertility restoration for these restorers was studied. The results showed that F1s between NJCMS1A and its restorers were completely male-fertile. The numbers of fertile and sterile plants in the F2 population of Cross I (NJCMS1A × N23601) and Cross II (NJCMS1A × N23683) corresponded to a segregation ratio of 15:1, and the numbers of non-segregation lines, 3:1 segregation lines and 15:1 segregation lines in F2:3 of the same two crosses fitted a 7:4:4 genotypic segregation ratio. The testcross BC1F1s between the F1s of the above two crosses and NJCMS1A, NJCMS1B showed a 3:1 segregation ratio. Accordingly, it was inferred that two pairs of duplicate dominant genes controlled the male fertility restoration of NJCMS1A in both crosses. Meanwhile, F2 of other 23 crosses between NJCMS1A and its 23 restorers showed a fertility segregation ratio of 3:1 or 15:1. The F1s of the five testcrosses between NJCMS1A and the F1s of five crosses selected from the above 23 crosses showed that fertility segregation was 3:1 in BC1F1s between NJCMS1A and F1s of the crosses of which fertility segregation fitted 15:1 in F2 population, while fertility segregation in BC1F1s was 1:1 for those fertility segregation fitted 3:1 in F2 population. Allelism tests showed that restore genes of all restorers in the experiment were allelic to two pairs of dominant genes. All results showed that some restorers bore one pair of dominant restore gene and the others bore two pairs of duplicate dominant gene. The mechanism of F1 male sterility of the cross N8855 × N2899 was discussed.

Development of a cytoplasmic-nuclear male-sterile line of soybean

The F1 of N8855 x N2899, a cross between two cultivars of G. max (L.) Merr., was found to be male-sterile. After it was back-crossed with the recurrent parent N2899 for four successive generations, a cytoplasmic-nuclear male-sterile line and its maintainer line, designated as NJCMS1A and NJCMS1B, respectively, were obtained. NJCMS1A was stable in male sterility with 98.29% plants being male-sterile at 0% pollen germination, while its female fertility was normal. The pollen abortion of NJCMS1A occurred at the binucleate stage. Then the vacuolation and disintegration of cytoplasm became further pronounced in NJCMS1A pollen. In addition, the abnormal phenomenon of 2 ∼ 3 styles surrounded by 20 ∼ 30 stamens was found in a few flowers of some male-sterile plants at BC1F1 and BC2F1.

Registration of Pearl Millet Cytoplasmic‐Nuclear Male‐Sterile Line ICMA‐5

Crop ScienceVolume 38, Issue 2 cropsci1998.0011183X003800020082x p. 556-556 Registration of Genetic Stocks Registration of Pearl Millet Cytoplasmic-Nuclear Male-Sterile Line ICMA-5 K. N. Rai, Corresponding Author K. N. Rai k.rai@cgnet.com Genetic Enhancement Div., ICRISAT Asia Center, Patancheru, 502 324 Andhra Pradesh, IndiaCorresponding author (k.rai@cgnet.com)(for 1998krai@unlvm.unl.edu).Search for more papers by this authorA. S. Rao, A. S. Rao Genetic Enhancement Div., ICRISAT Asia Center, Patancheru, 502 324 Andhra Pradesh, IndiaSearch for more papers by this author K. N. Rai, Corresponding Author K. N. Rai k.rai@cgnet.com Genetic Enhancement Div., ICRISAT Asia Center, Patancheru, 502 324 Andhra Pradesh, IndiaCorresponding author (k.rai@cgnet.com)(for 1998krai@unlvm.unl.edu).Search for more papers by this authorA. S. Rao, A. S. Rao Genetic Enhancement Div., ICRISAT Asia Center, Patancheru, 502 324 Andhra Pradesh, IndiaSearch for more papers by this author First published: 01 March 1998 https://doi.org/10.2135/cropsci1998.0011183X003800020082xCitations: 1AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article.Citing Literature Volume38, Issue2March–April 1998Pages 556-556 RelatedInformation