Cytoplasmic Genetic Male Sterility System Research Articles

Genetics of fertility restoration in A2‐based cytoplasmic genetic male sterility system in pigeonpea (Cajanus cajan)

AbstractThe three short duration cytoplasmic genetic male sterility (CGMS) hybrids developed using A2 (Cajanus scarabeoides) cytoplasm‐based male sterile lines (CORG 990047A, CORG 990052A and CORG 7A) and the restorer inbred AK 261322 and their segregating populations (F2 and BC1F1) were subjected to the study of inheritance of fertility restoration in pigeonpea. The fertility restoration was studied based on three different criteria, namely, anther colour, pollen grain fertility and pollen grain morphology and staining. The F2 and BC1F1 populations of the three crosses, namely, CORG 990047A × AK 261322, CORG 990052A × AK 261322 and CORG 7A × AK 261322, segregated in the ratio of 3:1 and 1:1, for anther colour (yellow:pale yellow), pollen grain fertility (fertile:sterile) and for pollen grain morphology and staining. The above study confirmed that the trait fertility restoration was controlled by single dominant gene. This finding can be utilized for the identification of potential restorers, which can be further used in the development of CGMS‐based hybrids in pigeonpea.

Genetics of fertility restoration in A1 Cytoplasmic Genetic Male Sterility (CGMS) systems in Sorghum (Sorghum bicolor L. Moench)

The cause of Cytoplasmic Genetic Male Sterility (CGMS) is specific nuclear and mitochondrial interactions. Almost all commercial sorghum hybrids were developed using the A1 cytoplasmic genetic male sterility system. Understanding the inheritance of fertility restoration in sorghum for A1 cytoplasm, for example, can improve the selection efficiency of restorer lines for increased seed production. In a cross of male sterile line 296A with A1 cytoplasm and restorer lines comprised of a set of Recombinant Inbred Lines (RILs), the inheritance pattern of fertility restoration of sorghum was studied. The F1 hybrid was completely fertile, revealing the dominant nature of fertility restoration, which is controlled by one or two major genes with modifiers. In this study, the genetics of fertility restoration of the A1 cytoplasmic nuclear male sterility system (CGMS) in sorghum were investigated in segregating F2 and BC1 populations of A1 cytoplasm crosses. Fertility restoration was governed by a monogenic inheritance (3F:1S) mechanism represented by a single dominant gene responsible for fertility restoration in all of the crosses studied.

Developing rice hybrids for temperate conditions using three line approach

Exploitation of heterosis in the form of hybrid rice is yet to be exploited at commercial level in the temperate regions of India. The present study is attempted to develop rice hybrids for the temperate conditions of Kashmir valley by utilizing the cytoplasmic genetic male sterility system (CGMS). Among the four CMS lines evaluated, the genotype SKUA-7A and SKUA-11A had desirable performances. The 24 test crosses developed involving these CMS lines were evaluated for spikelet fertility and pollen fertility. Moreover, the highest standard heterosis for grain yield and other yield attributes over the check varieties (Jehlum and Shalimar Rice-3) was recorded in the cross combination K15-34 followed by K15-31 and K15-40. Pollen parents of all the three test crosses on screening with RM-6100, DDRMRf3-10 and DRCG-Rf4-14 markers revealed presence of both Rf3 and Rf4 genes responsible for fertility restoration. Besides, 39 genotypes were screened for fertility restoration and the lines RL-2, RL-5, RL-6, RL-7, RL-10, Pusa Sugandh3 and Kohsar were identified to carry homozygous alleles at both Rf3 and Rf4 loci. These genotypes can thus be used as promising restores for the development of temperate rice hybrids.

Genetic Analysis of Some Quantitative Traits in Hybrid Rice with Utilizing Cytoplasmic Genetic Male Sterility System

Genetic Analysis of Some Quantitative Traits in Hybrid Rice with Utilizing Cytoplasmic Genetic Male Sterility System

Suitability of Maintainers and Restorers for CMS Lines in Rice

Hybrid rice technology has been successfully developed and is one of the potent options for increasing rice production. The use of cytoplasmic genetic male sterility system in developing hybrids in crops is possible only when effective restorers are identified. Pollen (or) spikelet fertility or both have been used as an index to fix the restoration ability of the lines. In the present investigation 19 genotypes were crossed with four stable CMS lines during Rabi 2009- 2010 at Paddy Breeding Station, Coimbatore. Genotypes were categorized as effective restorers (> 80 % spikelet fertility), partial restorers (20-79% spikelet fertility), partial maintainers (10-19 % spikelet fertility) and maintainers (<10 % spikelet fertility). A total of eighteen effective restorers and eight maintainers were identified among 100 genotypes against four CMS lines. The pollen fertility per cent of hybrids varied from 0 to 98.30%. The spikelet fertility of F1s ranged from 0 (IR 80151 A x CB 06 107) to 98.65 (TNAU CMS 2A x CB 06 734). Maximum number of maintainers were observed against IR 80151A. The maximum number of effective restorers were observed against TNAU CMS 2A. The identified restorers and maintainers could be utilized for development of new rice hybrids and CMS lines respectively in future.

Genetic analysis of fertility restoration genes for WA-type cytoplasmic male sterility in Iranian restorer rice line DN-33-18.

Cytoplasmic genetic male sterility system can be used to exploit heterosis in grain crops only when the effective restorer lines are available. Crosses between an Iranian CMS line Neda A with three newly developed lines DN-33-1, DN-33-18 and DN-32-6 showed that only the cross of Neda-A/DN-33-18 had more than 80% pollen and grain fertility in F1 generation. The inheritance of fertility restoration in F 2 population of this cross was evaluated at flowering and grain filling stages. Pollen staining test with 1% I 2 KI solution showed segregation ratio of 15:1 (fertile: sterile), representing two nuclear independent dominant genes controlling the trait carried by fertile parent DN-33-18. Segregation for spikelet fertility in F 2 confirmed the results of pollen fertility test. Molecular tagging of fertility restorer genes with SSR markers showed that four markers RM258, RM171, RM591 and RM3148 produced polymorphic bands between two parents. Linkage analysis on F 2 recessive class showed that RM258 and RM171 (on chromosome 10) flanked to restorer gene Rf4 at the distances of 3.1 and 6.3 cm, respectively. In this study polymorphism was not detected for Rf3 gene using SSR markers RM1, RM443, RM315 and RM294 on chromosome 1 of rice but we found new SSR marker RM3148 linked with Rf locus at a genetic distance of 19.7 cm. Key words : Rice, cytoplasmic male sterility (CMS), inheritance, molecular tagging, simple sequence repeat (SSR) markers.

Identification and characterization of new sources of cytoplasmic male sterility in rice

AbstractSearch for male sterility‐inducing cytoplasm in wild species of the genus Oryza was attempted with a view to diversify the base of the cytoplasmic genetic male sterility system currently used in the development of commercial rice hybrids. A total of 132 interspecific crosses were made involving accessions of four wild and two cultivated species, all belonging to the A genome. Wild accessions possessing sterility‐inducing cytoplasms were identified following reciprocal and sterile F2 backcross methods. Sterile segregants were pursued through substitution backcrosses to develop cytoplasmic male‐sterile (CMS) lines. CMS lines were developed with the cytoplasm of either O. rufipogon (VNI) or O. nivara (DRW 21018, DRW 21001, DRW 21039, DRW 21030 and RPW 21111). Based on shape, staining, and abortive pattern of pollen and also on type of interaction with a set of restorers and maintainers for known cytoplasmic male steriles of WA source (V 20A), the newly‐developed CMS lines were grouped into four classes. Of these, RPMS 1 and RPMS 2 showed gametophytic male sterility with a restorer reaction different from WA cytoplasmic male‐sterile stocks.

Genetics of fertility restoration of ‘Wild Abortive’ cytoplasmic male sterility in rice, Oryza sativa L.

Genetics of fertility restoration1 in six varieties and breeding lines of rice was studied in ‘Wild Abortive’ cytoplasmic genetic male sterility system using cytoplasmic male sterile lines V 20 A and IR 54752 A. Fertility evaluation of the plants in F2 and testcross populations of the crosses of V 20 A with PR 103, PR 106 and PAU 502-94-1, and IR 54752 A with PAU 1124-36-1 and PAU 1126-1-1 revealed that fertility restoration in PR 103, PR 106, PAU 502-94-1, PAU 1124-36-1 and PAU 1126-1-1 was controlled by two independently segregating dominant genes. The two genes appeared to have additive effects; one of them being stronger than the other in imparting fertility restoration. Data on spikelet fertility of the plants in F2 and testcross populations of V 20 A/UPR 82-1-1 cross showed that fertility restoration in UPR 82-1-1 was controlled by two independently segregating dominant genes which exhibited recessive epistatic interaction.