Flowering is an indispensable phenomenon of natural reproduction. To enter in the reproductive ph... more Flowering is an indispensable phenomenon of natural reproduction. To enter in the reproductive phase, most plant species get critical signals from different environmental factors which facilitate the conversion of their vegetative buds into reproductive tissues. The major factors that influence the appearance of flowers are moisture stress, temperature, photoperiod and radiation. According to Bernier et al. (1993) these factors are perceived by different plant parts. For example, leaves are affected by photoperiod and radiation; while temperature is perceived by all plant parts. Similarly, vernalization affects shoot apex and moisture availability is perceived by roots. These external determinants do not act independently and their interaction is inevitable and a particular factor may alter or substitute the direct effect of the other factors; and this may change the threshold level of individual factor in inducing flowering. Since at a given point of time, these environmental factors may act on different parts of the plant in their own way, the interaction among their gene products (proteins) may decide the transition of the vegetative buds into reproductive buds. Once flowering is induced in the plants, the further development of reproductive parts leads to differentiation into male/female gametes which participate in the natural reproduction. In this processes also, certain environmental factors play an active role and any departure from the normal process of microsporogenesis/ megasporogenesis leads to disorders such as male or female sterility. In this chapter the authors have not attempted a thorough review of male sterility systems of food crops but restricted to environment-sensitive male sterility with brief description of
386 Horticulture for Nutrition Security their origin, possible variants, maintenance and utilization in two-parent hybrid breeding.
Hybrid pigeonpea [Cajanus cajan (L.) Millsp.] breeding technology based on cytoplasmic-genetic ma... more Hybrid pigeonpea [Cajanus cajan (L.) Millsp.] breeding technology based on cytoplasmic-genetic male sterility (CMS) was recently developed ICRISAT, Patancheru in India. A program was initiated to track the purity of female parental lines by incorporating an obcordate leaf shape marker in established male sterile A-lines. Seven obcordate A-lines developed by backcrossing and selection were crossed with four known fertility restorers in line x tester mating design to study their general and specific combining ability. Higher magnitude of specific combining ability (SCA) effect showed that, hybrid yield was under the control of non-additive genes. Among A-lines, ICPA 2204 was the best general combiner. Among testers, ICPL 20116 was the best general combiner. Among hybrids, ICPA 2208 x ICPL 20108 a cross between high general combining ability (GCA) parents was the best with positive significant SCA effect and higher mean performance for grain yield, 100-seed mass, number of seeds/pod an...
Cytoplasmic male sterility (CMS) has been extensively exploited in commercial pigeonpea hybrid br... more Cytoplasmic male sterility (CMS) has been extensively exploited in commercial pigeonpea hybrid breeding system, however molecular mechanism responsible behind this system is unknown. To understand the underlying molecular mechanism involved in A4 CMS system, 34 genes were analyzed for length variation and expression profiling between CMS line (ICPA 2039) and its maintainer (ICPB 2039). As a result, nad4l showed 13.6 folds higher expression in CMS line as compared to its maintainer and nad7a showed 10bp deletion between these lines. Protein structure evaluation of amplicons of nad4l and nad7a for ICPA 2039 and ICPB 2039 revealed conformational changes for nad7a indicating its association with CMS. While analyzing this gene across different CMS lines derived from A4 system, the 10 bp deletion was found in all the CMS lines. Furthermore, analysis of 10 bp deletion across different CMS systems (A1-A8) showed specificity of this deletion to only A4 CMS. In summary, this study provided st...
With 1 figure and 4 tables AbstractCultivated pigeonpea (Cajanus cajan L. Millsp.) has a narrow g... more With 1 figure and 4 tables AbstractCultivated pigeonpea (Cajanus cajan L. Millsp.) has a narrow genetic base; hence, utilization of wild relatives in the crossing programme would broaden its genetic base and introduce useful traits. Cajanus platycarpus (Benth.) Maesen, an annual wild relative from the tertiary gene pool, was successfully crossed with the cultigen, utilizing hormone‐aided pollinations, embryo rescue and tissue culture techniques, and backcrossed using cultigen as the recurrent parent. Advance generation progeny showed a range of useful traits such as resistance to phytophthora blight, pod borer, bruchid and podfly resistance. Variation was also observed for plant type, growth habit and seed colour. A new source of cytoplasmic male sterility was identified in one of the progeny lines. Molecular analysis of the progeny after four backcrosses showed the presence of genomic segments from C. platycarpus accompanied by the presence of recombinant DNA sequences signifying r...
ABSTRACT One of the most attractive features of pigeonpea, relative to other legume crops, is its... more ABSTRACT One of the most attractive features of pigeonpea, relative to other legume crops, is its tolerance to drought stress. In order to understand the molecular mechanism of this unique feature, 511 universally stressed protein (USP) were analyzed across the Viridiplantae database in an earlier study (Nature Biotechnology 2012, 30:83-89). Out of these 511 proteins, 427 showed homology with legumes and 111 of these proteins had homologous USP domain. The Pfam USP family PF00582 domain (E value cutoff of 1.0), using the Hidden Markov Models (HMM), has been searched in pigeonpea genome sequence (version 5.0). In brief, a total of 51 genes showed close similarity to USP domain. Subsequently, primer pairs were designed for all the selected 51 genes to undertake differential gene expression studies on three genotypes namely ICPL 151, ICPL 227 and ICPL 8755, segregating for drought tolerance. qRT-PCR assays are in progress and updated results will be presented in the conference. In summary, the study is expected to identify and validate drought responsive genes that could be useful for enhancing drought tolerance in other crops especially legume species.
Wild Crop Relatives: Genomic and Breeding Resources, 2010
Pigeonpea is an important crop in the semi-arid tropics. Although ample morphological diversity i... more Pigeonpea is an important crop in the semi-arid tropics. Although ample morphological diversity is exhibited by pigeonpea as a crop, the same is not true at the molecular level. The crop has a rich source of variability in the form of wild species, which have played a major role in the introduction of disease resistance, good agronomic traits such as
... of hybrid parents and purity assessment of ICPH 2438 hybrid of pigeonpea [Cajanus cajan (L.) ... more ... of hybrid parents and purity assessment of ICPH 2438 hybrid of pigeonpea [Cajanus cajan (L.) Millspaugh] Rachit K. Saxena Kulbhushan Saxena Rajeev K. Varshney Received: 21 October 2009 / Accepted: 5 May 2010 Ó Springer Science+Business Media BV 2010 ...
Molecular markers are the most powerful genomic tools to increase the efficiency and precision of... more Molecular markers are the most powerful genomic tools to increase the efficiency and precision of breeding practices for crop improvement. Progress in the development of genomic resources in the leading legume crops of the semi-arid tropics (SAT), namely, chickpea (Cicer arietinum), pigeonpea (Cajanus cajan) and groundnut (Arachis hypogaea), as compared to other crop species like cereals, has been very slow. With the advances in next-generation sequencing (NGS) and high-throughput (HTP) genotyping methods, there is a shift in development of genomic resources including molecular markers in these crops. For instance, 2,000 to 3,000 novel simple sequence repeats (SSR) markers have been developed each for chickpea, pigeonpea and groundnut. Based on Sanger, 454/FLX and Illumina transcript reads, transcriptome assemblies have been developed for chickpea (44,845 transcript assembly contigs, or TACs) and pigeonpea (21,434 TACs). Illumina sequencing of some parental genotypes of mapping populations has resulted in the development of 120 million reads for chickpea and 128.9 million reads for pigeonpea. Alignment of these Illumina reads with respective transcriptome assemblies have provided more than 10,000 SNPs each in chickpea and pigeonpea. A variety of SNP genotyping platforms including GoldenGate, VeraCode and Competitive Allele Specific PCR (KASPar) assays have been developed in chickpea and pigeonpea. By using above resources, the first-generation or comprehensive genetic maps have been developed in the three legume speciesmentioned above. Analysis of phenotyping data together with genotyping data has provided candidate markers for drought-tolerance-related root traits in chickpea, resistance to foliar diseases in groundnut and sterility mosaic disease (SMD) and fertility restoration in pigeonpea. Together with these traitassociated markers along with those already available, molecular breeding programmes have been initiated for enhancing drought tolerance, resistance to fusarium wilt and ascochyta blight in chickpea and resistance to foliar diseases in groundnut. These trait-associated robust markers along with other genomic resources including genetic maps and genomic resources will certainly accelerate crop improvement programmes in the SAT legumes.
Flowering is an indispensable phenomenon of natural reproduction. To enter in the reproductive ph... more Flowering is an indispensable phenomenon of natural reproduction. To enter in the reproductive phase, most plant species get critical signals from different environmental factors which facilitate the conversion of their vegetative buds into reproductive tissues. The major factors that influence the appearance of flowers are moisture stress, temperature, photoperiod and radiation. According to Bernier et al. (1993) these factors are perceived by different plant parts. For example, leaves are affected by photoperiod and radiation; while temperature is perceived by all plant parts. Similarly, vernalization affects shoot apex and moisture availability is perceived by roots. These external determinants do not act independently and their interaction is inevitable and a particular factor may alter or substitute the direct effect of the other factors; and this may change the threshold level of individual factor in inducing flowering. Since at a given point of time, these environmental factors may act on different parts of the plant in their own way, the interaction among their gene products (proteins) may decide the transition of the vegetative buds into reproductive buds. Once flowering is induced in the plants, the further development of reproductive parts leads to differentiation into male/female gametes which participate in the natural reproduction. In this processes also, certain environmental factors play an active role and any departure from the normal process of microsporogenesis/ megasporogenesis leads to disorders such as male or female sterility. In this chapter the authors have not attempted a thorough review of male sterility systems of food crops but restricted to environment-sensitive male sterility with brief description of
386 Horticulture for Nutrition Security their origin, possible variants, maintenance and utilization in two-parent hybrid breeding.
Hybrid pigeonpea [Cajanus cajan (L.) Millsp.] breeding technology based on cytoplasmic-genetic ma... more Hybrid pigeonpea [Cajanus cajan (L.) Millsp.] breeding technology based on cytoplasmic-genetic male sterility (CMS) was recently developed ICRISAT, Patancheru in India. A program was initiated to track the purity of female parental lines by incorporating an obcordate leaf shape marker in established male sterile A-lines. Seven obcordate A-lines developed by backcrossing and selection were crossed with four known fertility restorers in line x tester mating design to study their general and specific combining ability. Higher magnitude of specific combining ability (SCA) effect showed that, hybrid yield was under the control of non-additive genes. Among A-lines, ICPA 2204 was the best general combiner. Among testers, ICPL 20116 was the best general combiner. Among hybrids, ICPA 2208 x ICPL 20108 a cross between high general combining ability (GCA) parents was the best with positive significant SCA effect and higher mean performance for grain yield, 100-seed mass, number of seeds/pod an...
Cytoplasmic male sterility (CMS) has been extensively exploited in commercial pigeonpea hybrid br... more Cytoplasmic male sterility (CMS) has been extensively exploited in commercial pigeonpea hybrid breeding system, however molecular mechanism responsible behind this system is unknown. To understand the underlying molecular mechanism involved in A4 CMS system, 34 genes were analyzed for length variation and expression profiling between CMS line (ICPA 2039) and its maintainer (ICPB 2039). As a result, nad4l showed 13.6 folds higher expression in CMS line as compared to its maintainer and nad7a showed 10bp deletion between these lines. Protein structure evaluation of amplicons of nad4l and nad7a for ICPA 2039 and ICPB 2039 revealed conformational changes for nad7a indicating its association with CMS. While analyzing this gene across different CMS lines derived from A4 system, the 10 bp deletion was found in all the CMS lines. Furthermore, analysis of 10 bp deletion across different CMS systems (A1-A8) showed specificity of this deletion to only A4 CMS. In summary, this study provided st...
With 1 figure and 4 tables AbstractCultivated pigeonpea (Cajanus cajan L. Millsp.) has a narrow g... more With 1 figure and 4 tables AbstractCultivated pigeonpea (Cajanus cajan L. Millsp.) has a narrow genetic base; hence, utilization of wild relatives in the crossing programme would broaden its genetic base and introduce useful traits. Cajanus platycarpus (Benth.) Maesen, an annual wild relative from the tertiary gene pool, was successfully crossed with the cultigen, utilizing hormone‐aided pollinations, embryo rescue and tissue culture techniques, and backcrossed using cultigen as the recurrent parent. Advance generation progeny showed a range of useful traits such as resistance to phytophthora blight, pod borer, bruchid and podfly resistance. Variation was also observed for plant type, growth habit and seed colour. A new source of cytoplasmic male sterility was identified in one of the progeny lines. Molecular analysis of the progeny after four backcrosses showed the presence of genomic segments from C. platycarpus accompanied by the presence of recombinant DNA sequences signifying r...
ABSTRACT One of the most attractive features of pigeonpea, relative to other legume crops, is its... more ABSTRACT One of the most attractive features of pigeonpea, relative to other legume crops, is its tolerance to drought stress. In order to understand the molecular mechanism of this unique feature, 511 universally stressed protein (USP) were analyzed across the Viridiplantae database in an earlier study (Nature Biotechnology 2012, 30:83-89). Out of these 511 proteins, 427 showed homology with legumes and 111 of these proteins had homologous USP domain. The Pfam USP family PF00582 domain (E value cutoff of 1.0), using the Hidden Markov Models (HMM), has been searched in pigeonpea genome sequence (version 5.0). In brief, a total of 51 genes showed close similarity to USP domain. Subsequently, primer pairs were designed for all the selected 51 genes to undertake differential gene expression studies on three genotypes namely ICPL 151, ICPL 227 and ICPL 8755, segregating for drought tolerance. qRT-PCR assays are in progress and updated results will be presented in the conference. In summary, the study is expected to identify and validate drought responsive genes that could be useful for enhancing drought tolerance in other crops especially legume species.
Wild Crop Relatives: Genomic and Breeding Resources, 2010
Pigeonpea is an important crop in the semi-arid tropics. Although ample morphological diversity i... more Pigeonpea is an important crop in the semi-arid tropics. Although ample morphological diversity is exhibited by pigeonpea as a crop, the same is not true at the molecular level. The crop has a rich source of variability in the form of wild species, which have played a major role in the introduction of disease resistance, good agronomic traits such as
... of hybrid parents and purity assessment of ICPH 2438 hybrid of pigeonpea [Cajanus cajan (L.) ... more ... of hybrid parents and purity assessment of ICPH 2438 hybrid of pigeonpea [Cajanus cajan (L.) Millspaugh] Rachit K. Saxena Kulbhushan Saxena Rajeev K. Varshney Received: 21 October 2009 / Accepted: 5 May 2010 Ó Springer Science+Business Media BV 2010 ...
Molecular markers are the most powerful genomic tools to increase the efficiency and precision of... more Molecular markers are the most powerful genomic tools to increase the efficiency and precision of breeding practices for crop improvement. Progress in the development of genomic resources in the leading legume crops of the semi-arid tropics (SAT), namely, chickpea (Cicer arietinum), pigeonpea (Cajanus cajan) and groundnut (Arachis hypogaea), as compared to other crop species like cereals, has been very slow. With the advances in next-generation sequencing (NGS) and high-throughput (HTP) genotyping methods, there is a shift in development of genomic resources including molecular markers in these crops. For instance, 2,000 to 3,000 novel simple sequence repeats (SSR) markers have been developed each for chickpea, pigeonpea and groundnut. Based on Sanger, 454/FLX and Illumina transcript reads, transcriptome assemblies have been developed for chickpea (44,845 transcript assembly contigs, or TACs) and pigeonpea (21,434 TACs). Illumina sequencing of some parental genotypes of mapping populations has resulted in the development of 120 million reads for chickpea and 128.9 million reads for pigeonpea. Alignment of these Illumina reads with respective transcriptome assemblies have provided more than 10,000 SNPs each in chickpea and pigeonpea. A variety of SNP genotyping platforms including GoldenGate, VeraCode and Competitive Allele Specific PCR (KASPar) assays have been developed in chickpea and pigeonpea. By using above resources, the first-generation or comprehensive genetic maps have been developed in the three legume speciesmentioned above. Analysis of phenotyping data together with genotyping data has provided candidate markers for drought-tolerance-related root traits in chickpea, resistance to foliar diseases in groundnut and sterility mosaic disease (SMD) and fertility restoration in pigeonpea. Together with these traitassociated markers along with those already available, molecular breeding programmes have been initiated for enhancing drought tolerance, resistance to fusarium wilt and ascochyta blight in chickpea and resistance to foliar diseases in groundnut. These trait-associated robust markers along with other genomic resources including genetic maps and genomic resources will certainly accelerate crop improvement programmes in the SAT legumes.
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Papers by kulbhushan saxena
386 Horticulture for Nutrition Security
their origin, possible variants, maintenance and utilization in two-parent hybrid breeding.
386 Horticulture for Nutrition Security
their origin, possible variants, maintenance and utilization in two-parent hybrid breeding.