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Plant breeding needs to embrace genetic innovations to ensure stability in crop yields under fluctuating climatic conditions. Development of commercial hybrid varieties has proven to be a sustainable and economical alternative to deliver superior yield, quality and resistance with uniformity in a number of food crops. Cytoplasmic male sterility (CMS), a maternally inherited inability to produce functional pollen, facilitates a three-line system for efficient hybrid seed production strategies in crops. The CMS system has illustrated its potential as a robust pollination control mechanism to support the billion-dollar seed industry. In plants, CMS arises due to a genomic conflict between mitochondrial open reading frames (orfs) and nuclear-encoding restoration-of-fertility (Rf) genes, leading to floral abnormalities and pollen sterility. Research on pollen sterility and fertility restoration provides deeper insights into cytoplasmic-nuclear interplay in plants and elucidates key molecular targets for hybrid breeding in crops. More recently, programmable gene editing (e.g., TALEN, CRISPR–Cas) has emerged as a promising tool to functionally validate CMS and Rf genes and obviate the need for pollen donors or Rf-genes for hybrid breeding. Modern genomic prediction models have allowed establishment of high-performing heterotic groups and patterns for sustaining long-term gain in hybrid breeding. This article reviews latest discoveries elucidating the molecular mechanisms behind CMS and fertility restoration in plants. We then present our perspective on how evolving genetic technologies are contributing to advance fundamental knowledge of the CMS-Rf genetic system for producing crop hybrids with high heterosis. [ABSTRACT FROM AUTHOR]

Cytoplasmic male sterility (CMS) offers a unique system to understand cytoplasmic nuclear crosstalk, and is also employed for exploitation of hybrid vigor in various crops. Pigeonpea A4-CMS, a predominant source of male sterility, is being used for efficient hybrid seed production. The molecular mechanisms of CMS trait remain poorly studied in pigeonpea. We performed genome-wide transcriptome profiling of A4-CMS line ICPA 2043 and its isogenic maintainer ICPB 2043 at two different stages of floral bud development (stage S1 and stage S2). Consistent with the evidences from some other crops, we also observed significant difference in the expression levels of genes in the later stage, i.e., stage S2. Differential expression was observed for 143 and 55 genes within the two stages of ICPA 2043 and ICPB 2043, respectively. We obtained only 10 differentially expressed genes (DEGs) between the stage S1 of the two genotypes, whereas expression change was significant for 582 genes in the case of stage S2. The qRT-PCR assay of randomly selected six genes supported the differential expression of genes between ICPA 2043 and ICPB 2043. Further, GO and KEGG pathway mapping suggested a possible compromise in key bioprocesses during flower and pollen development. Besides providing novel insights into the functional genomics of CMS trait, our results were in strong agreement with the gene expression atlas of pigeonpea that implicated various candidate genes like sucrose-proton symporter 2 and an uncharacterized protein along with pectate lyase, pectinesterase inhibitors, l-ascorbate oxidase homolog, ATPase, β-galactosidase, polygalacturonase, and aldose 1-epimerase for pollen development of pigeonpea. The dataset presented here provides a rich genomic resource to improve understanding of CMS trait and its deployment in heterosis breeding in pigeonpea. [ABSTRACT FROM AUTHOR]

Field studies were conducted at IIPR, Kanpur, India to estimate the intensity of field infestation on pigeonpea by pod fly and bruchids, and whether or not the phenotypic characters of the pigeonpea related to infestation caused by these insects. A total 32 long duration pigeonpea cultivars and advanced breeding lines were planted in augmented design along with check ‘Bahar’ and evaluated on the basis of exit holes and windows per pod, seed damage (%) by pod fly maggot and bruchid grub, 100 damaged seeds weight and relative resistant rating. Breeding line IPA-92 and a cultivar MA-3 were found to be highly resistant against pod fly, preventing them from crafting exit holes on pods and seed damage (%). Bruchid (C. chinensis and C. maculatus) was vulnerable to make windows on pods damaging the seeds of cultivars viz., IPA-15-1, IPA-15-5, IPA-15-7, IPA-15-10, IPA-15-12, IPA-15-14, MA-3, IPA-92, AZAD, IPA-234, BSMR-736, IPA-13-1 and IPA-37. Correlation studies revealed that pod fly infestation was the major biotic factor, which causes significant seeds damage and yield reduction in pigeonpea cultivars and advanced breeding lines. Those cultivars and breeding lines exhibited resistant reaction on pod fly and bruchids infestation might be used as donors in resistance breeding programme and including in IPM modules against these insect pests. [ABSTRACT FROM AUTHOR]

Pigeonpea productivity is greatly constrained by poor plant ideotype of existing Indian cultivars. Enhancing pigeonpea yield demands a renewed focus on restructuring the ideal plant type by using more efficient approaches like genomic tools. Therefore, the present study aims to identify and validate a set of QTLs/gene(s) presumably associated with various plant ideotype traits in pigeonpea. A total of 133 pigeonpea germplasms were evaluated along with four checks in the augmented design for various ideotype traits i.e. initiation of flowering (IF), days to 50% flowering (DFF), days to maturity (DM), plant height (PH), primary branches (PB), seeds per pod (SP) and pod length (PL). We observed significant genetic diversity in the germplasm lines for these traits. The genetic control of IF, DFF, DM and PH renders these traits suitable for detection of marker trait associations. By using residual maximum likelihood algorithm, we obtained appropriate variance-covariance structures for modeling heterogeneity, correlation of genetic effects and non-genetic residual effects. The estimates of genetic correlations indicated a strong association among earliness traits. The best linear unbiased prediction values were calculated for individual traits, and association analysis was performed in a panel of 95 diverse genotypes with 19 genic SSRs. Out of five QTL-flanking SSRs used here for validation, only ASSR295 could show significant association with FDR and Bonferroni corrections, and accounted for 15.4% IF, 14.2% DFF and 16.2% DM of phenotypic variance (PV). Remaining SSR markers (ASSR1486, ASSR206 and ASSR408) could not qualify false discovery rate (FDR) and Bonferroni criteria, hence declared as false positives. Additionally, we identified two highly significant SSR markers, ASSR8 and ASSR390 on LG 1 and LG 2, respectively. The SSR marker ASSR8 explained up to 22 and 11% PV for earliness traits and PB respectively, whereas ASSR390 controlled up to 17% PV for earliness traits. The validation and identification of new QTLs in pigeonpea across diverse genetic backgrounds brightens the prospects for marker-assisted selection to improve yield gains in pigeonpea. [ABSTRACT FROM AUTHOR]