Cytoplasmic Male Sterility System Research Articles

Yield performance and stability of CMS-based triticale hybrids.

CMS-based triticale hybrids showed only marginal midparent heterosis for grain yield and lower dynamic yield stability compared to inbred lines. Hybrids of triticale (×Triticosecale Wittmack) are expected to possess outstanding yield performance and increased dynamic yield stability. The objectives of the present study were to (1) examine the optimum choice of the biometrical model to compare yield stability of hybrids versus lines, (2) investigate whether hybrids exhibit a more pronounced grain yield performance and yield stability, and (3) study optimal strategies to predict yield stability of hybrids. Thirteen female and seven male parental lines and their 91 factorial hybrids as well as 30 commercial lines were evaluated for grain yield in up to 20 environments. Hybrids were produced using a cytoplasmic male sterility (CMS)-inducing cytoplasm that originated from Triticumtimopheevii Zhuk. We found that the choice of the biometrical model can cause contrasting results and concluded that a group-by-environment interaction term should be added to the model when estimating stability variance of hybrids and lines. midparent heterosis for grain yield was on average 3 % with a range from -15.0 to 11.5 %. No hybrid outperformed the best inbred line. Hybrids had, on average, lower dynamic yield stability compared to the inbred lines. Grain yield performance of hybrids could be predicted based on midparent values and general combining ability (GCA)-predicted values. In contrast, stability variance of hybrids could be predicted only based on GCA-predicted values. We speculated that negative effects of the used CMS cytoplasm might be the reason for the low performance and yield stability of the hybrids. For this purpose a detailed study on the reasons for the drawback of the currently existing CMS system in triticale is urgently required comprising also the search of potentially alternative hybridization systems.

Non-destructive in vitro selection of microspore-derived embryos with the fertility restorer gene for CMS Ogu-INRA in winter oilseed rape (Brassica napus L.)

article i nfo Article history: Received 16 June 2014 Accepted 29 September 2014 Available online xxxx Background:Microsporeembryogenesis and cytoplasmic male sterilitysystem(CMS)are twoapproacheswidely exploited in Brassica napus breeding for production of homozygous doubled haploid (DH) lines and F1 hybrids respectively. Cytoplasmic male sterility system (CMS) is one of the most important pollination systems for hybrid seed production and utilisation of doubled haploid system to quickly prepare fully homozygous fertility restorer lines for CMS Ogu-INRA is very beneficial. Generally, only a small part of microspore-derived embryos is used for plant regeneration, without any knowledge about their properties. Therefore, the possibility of early detection of desirable genotypes bearing a single dominant nuclear fertility restorer (Rfo) gene, can double the success of selection and reduce the production costs. Results: To maximize the efficiency and yield of regenerated microspore-derived embryos (MDEs) with the Rfo gene, a protocol for reliable and early, non-destructive selection of desired MDE genotypes was developed. The total amount of 636 cotyledonary embryos was tested by PCR, out of which 37% (237/636) were shown to bear the Rfo gene (instead of 50% according to the expected 1:1 segregation ratio for a single copy gene) and 218 of these fertility restorer plants were fully grown to flowering stage. New molecular marker has been demonstrated to have 100% of co-segregation with the phenotypic evaluation. Conclusion: Technique developed in this study provides early and non-destructive sampling of embryonic tissue and the use of new markers for simple and efficient control of the presence of Rfo gene in all accessions.

Male sterility of triticale lines generated through recombination of triticale and rye maintainers

The Triticum timopheevi cytoplasmic male sterility (cms) system in triticale (xTriticosecale Wittmack) suffers from a low frequency of maintainers and environmental instability of the male sterility. On the other hand, the Pampa cms system in rye (Secale cereale) exhibits strong male sterility and a low frequency of restorers. Here, we report generating hybrids between maintainers of the T. timopheevi cms system in triticale and maintainers of the rye Pampa cms system. Ten hybrids were obtained. Their hybridity was verified by PCR (polymerase chain reaction) using ISSR (inter simple sequence repeats) primers. The cms maintaining ability of F2 individuals and their progeny was tested. The F2 plants were crossed to male sterile lines of triticale carrying the T. timopheevi cytoplasm. Among 180 G1 offspring of these crosses, 71 (39.4%) were completely male sterile. Fourteen F2 individuals (7.8%), as well as their F2S1 and progeny, generated stable male sterility in G1, G1BC1 and G1BC2 generations after the crosses. Our results suggest that it is possible to produce a more stable cms system in triticale based on the T. timopheevi cytoplasm as compared to the existing one.

Development of Insect-Resistant Hybrid Rice by Introgressing the Bt Gene from Bt Rice Huahui 1 into II-32A/B, a Widely Used Cytogenic Male Sterile System

Huahui 1 is an elite transgenic male sterile restorer line of wild rice abortive-type that expresses a Bacillus thuringiensis (Bt) δ-endotoxin and provides effective and economic control of lepidopteran insects. To exploit Huahui 1 to develop a new Bt rice, the insertion site of the Bt gene was determined by thermal asymmetric interlaced PCR (TAIL-PCR). Bt was located in the promoter region of LOC.Os10g10360, approximately 5.35 Mb from the telomere of the short arm of chromosome 10. For the first time, a Bt cytoplasmic male sterile (CMS) system was developed by introgressing Bt from Huahui 1. The recipient CMS system used consisted of Indonesia paddy rice-type II-32B (maintainer line) and II-32A (male sterile line). Marker-assisted selection was used to increase selection efficiency in the backcrossing program. In BC5F1, the Bt plant 85015-8 was selected for further analyses, as it had the highest SSR marker homozygosity. In addition, the linkage drag of the foreign Bt gene in 85015-8 was minimized to 8.01-11.46 Mb. The foreign Bt gene was then delivered from 85015-8 into II-32A. The resultant Bt II-32A and Bt II-32B lines were both resistant to lepidopteran in field trials, and agronomic traits were not disturbed. The maintainability of II-32B, and the male sterility and general combining ability of II-32A, were not affected by the Bt introgression. This study demonstrates a simple and fast approach to develop Bt hybrid rice.

Sequencing of the chloroplast genomes of cytoplasmic male-sterile and male-fertile lines of soybean and identification of polymorphic markers

The RN-type cytoplasmic male sterility (CMS) system used to develop Hybsoy-1, the first commercial hybrid soybean, has been subsequently applied to generate nearly all released soybean hybrids. Although more than 3 years are needed to classify sterile (S) and normal male-fertile (F) cytoplasms by conventional crossing, such classifications can be performed rapidly using organellar DNA-based molecular markers. Except for fertility, the agronomic traits of CMS hybrid soybean sterile and maintainer lines are identical. Consequently, it is difficult to distinguish them by routine visual inspection in the mixture arising in the course of field planting and harvesting during breeding. In this study, we performed next-generation sequencing of chloroplast DNAs of F- and S-cytoplasmic soybeans, assembled and annotated the genomes, and identified polymorphisms distinguishing them. Chloroplast DNAs of F and S cytoplasms were very similar in size (152,215 and 152,222 base pairs) and GC contents (35.37%). Among 23 shared SNPs in gene coding regions, we identified four that could be used in conjunction with restriction endonucleases to distinguish S and F cytoplasms. Although CMS is likely associated with mitochondrial DNA, maternal transmission of mitochondrial and chloroplast DNAs allows polymorphisms in either genome to be used to classify soybean cytoplasms, aiding hybrid soybean cultivar development.

Workable male sterility systems for hybrid rice: Genetics, biochemistry, molecular biology, and utilization.

The exploitation of male sterility systems has enabled the commercialization of heterosis in rice, with greatly increased yield and total production of this major staple food crop. Hybrid rice, which was adopted in the 1970s, now covers nearly 13.6 million hectares each year in China alone. Various types of cytoplasmic male sterility (CMS) and environment-conditioned genic male sterility (EGMS) systems have been applied in hybrid rice production. In this paper, recent advances in genetics, biochemistry, and molecular biology are reviewed with an emphasis on major male sterility systems in rice: five CMS systems, i.e., BT-, HL-, WA-, LD- and CW- CMS, and two EGMS systems, i.e., photoperiod- and temperature-sensitive genic male sterility (P/TGMS). The interaction of chimeric mitochondrial genes with nuclear genes causes CMS, which may be restored by restorer of fertility (Rf) genes. The PGMS, on the other hand, is conditioned by a non-coding RNA gene. A survey of the various CMS and EGMS lines used in hybrid rice production over the past three decades shows that the two-line system utilizing EGMS lines is playing a steadily larger role and TGMS lines predominate the current two-line system for hybrid rice production. The findings and experience gained during development and application of, and research on male sterility in rice not only advanced our understanding but also shed light on applications to other crops.Electronic supplementary materialThe online version of this article (doi:10.1186/s12284-014-0013-6) contains supplementary material, which is available to authorized users.

Transcript analyses of the gene associated with CMS in Brassica napus

We analysed DNA and complementary DNA (cDNA) from two inbred lines (CMS-ARIT121 and CMS-ARIT2) along with their respective maintainer lines with eight known genes (atpa, atp6, atp9, coxI, coxII, orfB, orf222 and orf224) reported in other cytoplasmic male sterility (CMS) systems. DNA analyses indicated that only orf224 was different in the maintainer and CMS in ARIT121. Sequencing analysis indicated that CMS-ARIT121 has a similar sequence to that of polima CMS. However, CMS-ARIT2 was quite unique, with no sequence difference at DNA or cDNA level in all eight candidate genes, with the exception of a two-base substitution in the atp6 gene between the CMS and maintainer lines. The similar amplification pattern with all primers, especially orf224, indicates that CMS-ARIT2 is unique and does not correspond to polima, ogura or nap. However, further research is required to establish the causes of sterility in this cms, since we could not find any significant difference at transcript level between CMS-ARIT2 and its corresponding maintainer line. However, the same restorer PR121 as for CMS-ARIT121 was able to restore CMS-ARIT2, and as such can be used for hybrid seed production in Brassica napus L. Overall, this study provides important information for breeders selecting new cytoplasmic male sterility (CMS) in B. napus L. and use of molecular markers to identify CMS lines at early seedling stage that will enhance the B. napus L. breeding program.

Gene action and stability parameters for yield and yield components, maturity duration and protein content of CGMS lines, pollen fertility restorers and their hybrids in pigeonpea [Cajanus cajan (L.) Millsp.

Cytoplasmic genic male sterility system based hybrids were synthesized by line × tester design and evaluated with check GTH 1 in RBD at Sardarkrushinagar, Jagudan and Khedbrahma during kharif 2007. Analysis of variance in individual and across environments revealed significant differences among genotypes and existence of overall heterosis for seed yield per plant and other thirteen traits. The top ranking on the basis of standard heterosis were CMSGT087A × GTR0525 (116.40 %) followed by CMSGT087A × AGTR0534 (108.93 %), CMSGT0307A × AGTR0538 (99.21 %) and CMSGT 0301A × AGTR 0534 (95.51 %) for seed yield per plant and for one or two of its contributing traits. Combining ability analysis revealed presence of both additive and non-additive gene effects. The specific combining ability variance was found more compaired to general combining ability variance for all the characters under studied. This favored a hybrid breeding programme. In stability analysis, linear portion was considerably high for all the traits except for days to flower and pod length. The best stable hybrids for seed yield per plant over environments were CMSGT 308A × AGTR 0534, CMSGT 307A × AGTR 0543, CMSGT 0308A × AGTR 0536 and CMSGT 0311A × GTR 0525 and also recorded stability in any one or more of its contributing traits viz. pods per plant, branches per plant, seed per pod, pod length and test weight. Top ranking hybrids had high mean performance, high heterosis and desirable sca effects and stability for seed yield per plant. Therefore, these hybrids could be valuable for commercial exploitation.

Fertility restoration in three CMS systems of eggplant by the Rf genes of each other's systems and their SCAR marker

Three pollen non-formation type cytoplasmic male sterility (CMS) systems of eggplant (Solanum melongena L.) were developed in our previous study, through repeated backcrossing, by using wild Solanum species Solanum aethiopicum L. Aculeatum Group, Solanum anguivi Lam. and Solanum grandifolium C. V. Morton as the cytoplasm donor and eggplant ‘Uttara’ as the recurrent pollen parent. Each CMS system has male fertile (MF) line which carries the fertility restorer (Rf) genes for the pollen non-formation type sterility. In the present study, fertility restoration ability in three CMS systems of eggplant by the Rf genes of each other's systems was evaluated. The male sterile (MS) line of each CMS system was pollinated with the pollen of MF lines of other CMS systems as well as its own CMS system. Among the nine cross combinations, six groups were obtained from crossing MS lines with MF lines of other CMS systems and three groups were obtained from crossing MS lines with MF lines of their own CMS system. The segregation of MF and MS plants was fitted well with a 3:1 ratio in almost all cross combinations. The segregation patterns revealed that two independent dominant Rf genes restore fertility in each CMS system. Pollen stainability and in vitro pollen germination rate of the progenies obtained from different cross combinations were varied from 61.0 to 89.8% and 0.7 to 8.0%, respectively. Each Rf gene of three CMS systems restores fertility of other CMS systems as well as its own CMS system. Moreover, fertility recovery action in these three kinds of CMS is similar. DNA markers linked to Rf genes were screened by bulked segregant analysis (BSA) using random amplified polymorphic DNA (RAPD). A total of 420 primers were used, and more than 65% of the primers yielded a considerable number of RAPD fragments in both MF and MS bulks. Only one Operon primer OPAB10 gave a reproducible polymorphic band of 1.9kbp (OPAB101900) between bulks and was identified as linked to the Rf genes. Additionally, the RAPD marker OPAB101900 was converted to sequenced characterized amplified region (SCAR) marker designated as SCAB101900 by nucleotide sequencing. Findings of the present study may give us a potential way to explore CMS and the corresponding Rf genes from wild Solanum resources for the breeding program of eggplant.

Instability in mitochondrial membranes in Polima cytoplasmic male sterility of Brassica rapa ssp. chinensis

Cytoplasmic male sterility (CMS) is an important factor to observe heterosis in Brassica rapa. Although several studies have documented the rearrangements of mitochondrial DNA and dysfunction in the mitochondria have been observed in most types of CMS, the basis of the molecular mechanisms involved in these processes and other effects on CMS remain unclear. In this study, suppression subtractive hybridization was performed in the flowers of an alloplasmic Polima CMS system from B. rapa ssp. chinensis to identify genes that are differentially expressed between fertile and sterile plants. A total of 443 clones were isolated (156 were upregulated in fertile buds, and 287 were upregulated in sterile ones). Real-time RT-PCR further demonstrated the credibility of SSH. Among these genes, many membrane protein genes (LTP12, PIP2A, and GRP14) were inhibited in the sterile male line. Mitochondrial membrane potential (MMP) assay was then performed. Results showed that the sterile MMP was unstable and failed to create a potential difference; thus, mitochondrial dysfunction occurred. Moreover, abnormal microtubules and photosynthetic pathways were found in sterile male cells. Unstable MMP, nutritional deficiency, and abnormal microtubules were the causes of Polima CMS in Brassica campestris. H2O2, MDA, and O(2-), accumulated as byproducts of energy metabolism disorder in sterile male cells.

A codominant molecular marker in linkage disequilibrium with a restorer-of-fertility gene (Ms) and its application in reevaluation of inheritance of fertility restoration in onions

To reveal the linkage relationship between the Ms locus, a restorer-of-fertility gene for cytoplasmic male-sterility (CMS) caused by CMS-S cytoplasm in onion (Allium cepa L.) and previously reported molecular markers linked to the Ms locus, 11 recombinants selected from 4,273 segregating plants originating from the cross between male-sterile maternal and male-fertile paternal lines were analyzed. Results showed that genotypes of a codominant marker, jnurf12, were perfectly matched with the male-fertility phenotypes in all recombinants, but that this marker was not applicable in diverse breeding lines due to multiple band patterns. For the development of more reliable markers, a 12-bp indel was identified from the sequences which were obtained by genome walking, and was used to develop a simple PCR marker which was designated jnurf13. When 104 diverse breeding lines containing CMS-S cytoplasm were analyzed with the jnurf13 marker, male-fertility phenotypes of all breeding lines were perfectly matched with marker genotypes. To our surprise, phenotypes of 153 breeding lines containing CMS-T-like cytoplasm were also matched with genotypes of the jnurf13 marker which was linked to the Ms locus for the CMS-S system. Furthermore, phenotypes of four F2 populations containing CMS-T-like cytoplasm co-segregated perfectly with jnurf13 genotypes. Allelic segregation distortion was detected in two F2 populations using the jnurf13 maker. The results of this study were in conflict with a previous model for inheritance of fertility restoration in the CMS-T system. Therefore, we proposed a new model based on the data analyzed with the jnurf13 marker, which was in linkage disequilibrium with restorer-of-fertility genes for both CMS systems.

Development of a candidate gene marker for Rf 1 based on a PPR gene in cytoplasmic male sterile CMS-D2 Upland cotton

The cytoplasmic male sterility (CMS) system is convenient and efficient for hybrid seed production in Upland cotton (Gossypium hirsutum L.). However, it has not been widely used because of limited restorer lines carrying the restorer gene Rf1 in the CMS-D2 system. In this study, the fertility segregation in a backcross (BC8F1) population of 409 individuals and an F2 population of 695 plants confirmed that the fertility restoration was determined by one dominant restorer gene (Rf1). A sequence alignment showed that 13 Rf1-linked simple sequence repeat marker sequences were distributed on nine scaffolds of chromosome 9 in the sequenced D5 genome of G. raimondii Ulbrich. Ten pentotricopeptide repeat (PPR)-like genes were identified on two scaffolds, including Scaffold 333 where nine PPR-like genes were clustered in a region of about 160 kb. Among them, PPR-like gene Cotton_D_gene_10013437 was identified as the candidate for the Rf1 gene through a comparative sequence analysis of the homologous gene among sterile (A), maintainer (B) and restorer (R) lines, and co-segregation analysis. Compared with the non-restoring lines, the restorer had a 9-nucleotide (nt) insertion and a single nucleotide polymorphism (SNP) 8 nt upstream of the insertion at the 3′ untranslated regions (3′ UTRs) in this gene. A cleaved amplified polymorphic sequence (CAPS) marker named CAPS-R was developed from the SNP site using the restriction enzyme DraI, and was further used to track the restorer gene and its homozygous or heterozygous status in molecular breeding for restorer lines. A marker-assisted selection system using the Rf1-specific CAPS-R marker and a CMS-D2 cytoplasm-specific SCAR marker was established to distinguish the three-line hybrids from other genotypes.

Cytoplasmic male sterility in Brassicaceae crops.

Brassicaceae crops display strong hybrid vigor, and have long been subject to F1 hybrid breeding. Because the most reliable system of F1 seed production is based on cytoplasmic male sterility (CMS), various types of CMS have been developed and adopted in practice to breed Brassicaceae oil seed and vegetable crops. CMS is a maternally inherited trait encoded in the mitochondrial genome, and the male sterile phenotype arises as a result of interaction of a mitochondrial CMS gene and a nuclear fertility restoring (Rf) gene. Therefore, CMS has been intensively investigated for gaining basic insights into molecular aspects of nuclear-mitochondrial genome interactions and for practical applications in plant breeding. Several CMS genes have been identified by molecular genetic studies, including Ogura CMS from Japanese radish, which is the most extensively studied and most widely used. In this review, we discuss Ogura CMS, and other CMS systems, and the causal mitochondrial genes for CMS. Studies on nuclear Rf genes and the cytoplasmic effects of alien cytoplasm on general crop performance are also reviewed. Finally, some of the unresolved questions about CMS are highlighted.

Comparative analysis of fertility restoration genes for WA, Y, and DA cytoplasmic male sterility in rice

Rice chromosome single segment substitution line (SSSL) W23-19-06-06-11 with the genotype Rf3Rf3/Rf4Rf4, a strong restorer line for wild-abortive (WA) cytoplasmic male sterility (CMS), was recently identified from the SSSL library. To investigate the genetic mode of Rf genes and the genetic relationship among WA, yegong (Y), and dwarf-wildabortive (DA) CMS systems, the plants derived from three BC3F2 populations involving W23-19-06-06-11 and the three CMS lines, that carried the Rf3Rf3/Rf4Rf4, Rf3Rf3/rf4rf4, and rf3rf3/Rf4Rf4 genotypes and WA-, Y-, and DA-CMS cytoplasm, were selected and their pollen and spikelet fertility were evaluated. The results show that the genetic effect displayed a trend of Y-CMS > WA-CMS > DA-CMS in the genetic background of W23-19-06-06-11, the effect of Rf4 appeared to be slightly larger than that of Rf3, and their effects were additive for the three CMS systems. Two pairs of dominant genes governed the fertility restoration in pollen and spikelet in the W23-19-06-06-11 which indicates that the genetic mode of the Rf genes was a qualitative character for the three CMS systems.

Development of chloroplast‐specific microsatellite markers for molecular characterization of alloplasmic lines and phylogenetic analysis in wheat

AbstractWheat (Triticum aestivum L.) is strictly a self‐pollinated crop, where hybrid breeding requires well‐characterized cytoplasmic male sterile (CMS) lines. The CMS has mostly been developed by substituting nuclear genome of wheat into the cytoplasm from wild relatives. Molecular characterization of 90 genotypes including 82 CMS lines originating from five different species, namely Aegilops speltoides, Ae. kotschyi, Ae. variabilis, Triticum araraticum and T. timopheevii, and eight popular varieties was carried out. Consequently, a set of 25 microsatellite markers specific to chloroplast (cpSSRs) were designed and successfully validated for specificity of amplification. A total of 15 cpSSRs (60%) were found polymorphic, of which three cpSSRs (TaCM7, TaCM8 and TaCM11) in genic region and twelve cpSSRs were located in intergenic region. Phylogenetic analysis of genotypes using cpSSRs revealed two major groups well in accordance with respective origin. A set of cpSSRs and phylogeny of CMS belonging to different origins developed, which will be helpful for the improvement in CMS system in wheat. The genic cpSSRs can be used for the allele mining and evolutionary studies.

Development of Novel Cytoplasmic Male Sterile Source from Dongxiang Wild Rice (Oryza rufipogon)

This study was conducted to develop and characterize a novel cytoplasmic male sterile (CMS) source which was identified from Dongxiang wild rice (Oryza rufipogon) by crossing Dongxiang wild rice as female with Zhongzao 35, an indica inbred variety, as male and continuous backcrossing with Zhongzao 35. Observation under optical microscope manifested that this novel CMS belonged to typical abortion type with less pollen compared with wild abortive type cytoplasm (CMS-WA). Sequential planting showed that this novel CMS has complete and stable male sterility. Testcross experiment showed that all the 24 tested materials including maintainer and restorer lines of CMS-WA and Honglian type cytoplasm (CMS-HL) and other indica inbred varieties are the maintainers with complete maintaining ability, suggesting that this novel CMS has fertility restoration totally different from CMS-WA and CMS-HL and belongs to a novel type of CMS. So far, we only discovered a unique fertility restoration source for this novel CMS. Inheritance analysis showed that the fertility restoration of this CMS was governed by three pairs of independent dominant genes. Prospect for application of this novel CMS system in hybrid rice breeding was also discussed.

Interaction of Restorer Genes in ‘WA’-type Cytoplasmic Male Sterility System in Rice (Oryza sativa L.)

The inheritance of fertility restoration of ‘WA’ type of cytoplasmic male sterility system in rice was studied using three cytoplasmic male sterile (A) lines and their respective maintainer (B) lines and four restorer lines which were used in crossing to produce three generations (A × R) F1, (A × F1) BC1 and (A × R) F2. Segregation pattern in F2 generation for pollen fertility indicated that the fertility restoration ability was governed by two pairs of dominant genes (Rf 3 Rf 3 Rf 4 Rf 4 ), one of which was stronger in action than the other. The cross combinations, Pusa 6A × Basmati 564, Pusa 3A × HUR-FG-79 and Pusa 6A × HUR-FG-78 exhibited epistasis with incomplete dominance (F2 ratio 9:6:1 and BC1 ratio 1:2:1). In cross combinations, Pusa 3A × Basmati 564, Pusa 3A × HUR-FG-78 and Pusa 5A × Basmati 564, the fertility restoration was governed by dominant genes with recessive epistatic interaction (F2 ratio, 9:3:4 and BC1 ratio 1:1:2). Pusa 5A × HUR-FG-81 the only cross combination which exhibited dominant gene interaction (F2 ratio 12:3:1 and BC1 ratio 2:1:1). An allelism test involving four restorer lines revealed that Basmati 564, HUR-FG-81, HUR-FG-78 and HUR-FG-79 possessed different pairs of fertility restorer genes.

Pollen and seed fertility of the male fertile lines having the fertility restorer gene in three CMS systems of eggplant

In our previous study, three pollen non-formation type cytoplasmic male-sterility (CMS) systems of eggplant (Solanum melongena L.) were developed through repeated backcrossing, by using wild Solanum species S. aethiopicum L. Aculeatum Group, S. anguivi and S. grandifolium as the cytoplasm donor and eggplant ‘Uttara’ as the recurrent pollen parent. Each CMS system has male fertile line which carries the fertility restorer genes for the pollen non-formation type sterility. In the present study, pollen and seed fertility of the male fertile lines were studied to find out the possibilities of selfing and anther culture for the development of homozygous restorer and male-sterile lines. To confirm the utility of these methods we tried to apply the method of selfing and anther culture of the male fertile lines. Pollen fertility was assessed by pollen stainability in acetocarmine, in Lugol's solution and in vitro germination rate of pollen at three different stages of pollen maturation, such as, 2 days before anthesis, at anthesis and 2 days after anthesis. Pollen stainability with acetocarmine and in vitro germination rate of pollen in all three stages of pollen maturation were comparatively lower in the male fertile lines than eggplant ‘Uttara’. At anthesis, pollen stainability was about 50% and in vitro pollen germination was less than 20% in three male fertile lines. Pollen stainability with Lugol's solution revealed that the low pollen fertility of the male fertile lines would be caused by incomplete accumulation and degradation of starch during pollen maturation. The male fertile lines showed good fruit set percentage and produced an adequate amount of seeds in selfing and backcrossing. A restorer line homozygous for the fertility restorer gene with the cytoplasm of S. anguivi was developed by selfing and selection of the male fertile line. A doubled haploid male sterile and male fertile plants were obtained from anther culture of the male fertile lines with the cytoplasms of S. anguivi and S. grandifolium, respectively. Pollen and seed fertility study of the present study revealed that homozygous restorer and male-sterile lines could be developed by selfing and anther culture of the male fertile lines of eggplant.

Maintaining and restoring cytoplasmic male sterility systems in pepper (Capsicum annuum L.)

We studied the efficiency of maintaining and restoring cytoplasmic male sterility (CMS) systems in pepper (Capsicum annuum L.). An Rf-linked molecular marker was employed to analyze the interaction between 6 CMS lines (A), 5 maintainers (B), and 6 restorers (C). Sterility was maintained in the matings of lines 201A x 200B, 203A x 200B, 206A x 200B, 200A x 201B, 206A x 201B, 200A x 202B, 200A x 203B, 200A x 206B, and 201A x 206B. All 6 restorers restored the fertility of lines 200A, 202A, 203A, and 204A, except that 213C could not restore the fertility of lines 200A and 204A. However, the 6 restorers had diverse restoring abilities in individual CMS lines. The Rf-linked molecular marker was amplified by PCR in lines 207C, 208C, and 213C. This DNA marker was only found in the F1 hybrids M39, M14, M19, M25, M13, M20, and M22. We conclude that the restorers 208C and 207C can transmit the Rf gene or the Rf-linked marker to F1 hybrids.

Cytoplasm Has No Effect on the Yield and Quality of Biomass Sorghum Hybrids

The development of the biomass sorghum hybrid seed industry is contingent on the use of cytoplasmic male sterility. Within sorghum, there are several different cytoplasmic male sterility systems and it is important to determine early in development if cytoplasm will affect agronomic performance or composition characters. Thus, if there is a difference, then the best system can be deployed. The purpose of this study was to determine if cytoplasm per se influences agronomic performance of biomass sorghum using a set of iso-cytoplasmic hybrids. Three hybrid genotypes were produced in three different cytoplasms (A1, A2, and A3) for a total of nine hybrids. These hybrids were evaluated for plant height, biomass yield, and biomass composition in three Texas environments (Weslaco, College Station, and Halfway) in 2010. Across environments, significant differences existed among hybrids for both agronomic and compositional traits, but cytoplasm per se had no effect on any measured trait. Since cytoplasm did not effect on hybrid performance, any of the tested cytoplasms (A1, A2, and A3) can be deployed in hybrid biomass sorghums.