Expression analysis of candidate genes for abiotic stress tolerance in <i>Brassica</i> genotypes with contrasting osmotic stress tolerance

333-343Drought stresses adversely affect production of mustard as it is cultivated mostly as a rain-fed crop. Drought at critical stages of crop growth is one of the reasons for low productivity of mustard in India. We screened 38 genotypes of Indian mustard [Brassica juncea (L.) Czern] and Sinapis alba L. (white mustard), and identified genotypes with contrasting drought tolerance. To understand the molecular basis of drought tolerance in mustard, we analyzed expression pattern of orthologs of 24 validated Arabidopsis genes in mustard genotypes with contrasting drought tolerance. The candidate genes exhibited distinct expression pattern between stress tolerant and sensitive genotypes. All 24 genes analyzed in this study showed upregulation under drought stress at least in one of the genotypes examined. The present study highlighted the differential expression pattern of several drought responsive candidate genes in five different cultivars of Brassica juncea (L.) Czern and its wild relative S. alba. Drought stress specifically upregulated the expression of ERECTA, TMM, ABA1, AREB1, CYP707A, ROP10, SOS4, RabG3e, STT3a and SHN1 genes > 2-fold in one or more of the drought tolerant genotypes, but not in any of the susceptible genotypes. Only AREB1 and INO1 showed upregulation in all the genotypes under drought stress. Thus, this study revealed considerable association between drought stress induction of candidate genes and abiotic stress tolerance of B. juncea and S. alba genotypes. These genes will be useful for further understanding of drought tolerance and genetic improvement of oil seed Brassica crops

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Drought stresses adversely affect production of mustard as it is cultivated mostly as a rain-fed crop. Drought at critical stages of crop growth is one of the reasons for low productivity of mustard in India. We screened 38 genotypes of Indian mustard [Brassica juncea (L.) Czern] and Sinapis alba L. (white mustard), and identified genotypes with contrasting drought tolerance. To understand the molecular basis of drought tolerance in mustard, we analyzed expression pattern of orthologs of 24 validated Arabidopsis genes in mustard genotypes with contrasting drought tolerance. The candidate genes exhibited distinct expression pattern between stress tolerant and sensitive genotypes. All 24 genes analyzed in this study showed upregulation under drought stress at least in one of the genotypes examined. The present study highlighted the differential expression pattern of several drought responsive candidate genes in five different cultivars of Brassica juncea (L.) Czern and its wild relative S. alba. Drought stress specifically upregulated the expression of ERECTA, TMM, ABA1, AREB1, CYP707A, ROP10, SOS4, RabG3e, STT3a and SHN1 genes > 2-fold in one or more of the drought tolerant genotypes, but not in any of the susceptible genotypes. Only AREB1 and INO1 showed upregulation in all the genotypes under drought stress. Thus, this study revealed considerable association between drought stress induction of candidate genes and abiotic stress tolerance of B. juncea and S. alba genotypes. These genes will be useful for further understanding of drought tolerance and genetic improvement of oil seed Brassica crops