A major dwarfing region for plant height, asd1, was identified employing the next-generation sequencing-based QTL-Seq approach from a dwarf mutant and is demonstrated to be responsible for the dwarf nature with least penalty on yield in rice. The yield plateauing of modern rice is witnessed since many decades due to the narrow genetic base owing to the usage of a single recessive gene, i.e., semi-dwarf-1 (sd-1) for development of short-statured varieties throughout the world. This calls for the searching of alternate sources for short stature in rice. To this end, we made an attempt to uncover yet another, but valuable dwarfing gene employing next-generation sequencing (NGS)-based QTL-Seq approach. Here, we have identified a major QTL governing plant height on chromosome 1, i.e., alternate semi-dwarf 1 (asd1) from an F mapping population derived from a cross between a dwarf mutant, LND384, and a tall landrace, INRC10192. Fine mapping of asd1 region employing sequence-based indel markers delimited the QTL region to 67.51 Kb. The sequencing of the QTL region and gene expression analysis predicted a gene that codes for IWS1 (C-terminus family protein). Furthermore, marker-assisted introgression of the asd1 into tall landrace, INRC10192, reduced its plant height substantially while least affecting the yield and its component traits. Hence, this novel dwarfing gene, asd1, has profound implications in rice breeding.

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Background: In the current climate change scenario, high temperature stress is one of the major constraints limiting the yield of blackgram severely. The increasing global temperature is targeting the yield of blackgram by causing severe reproductive failures. In order to combat this problem, it is important and inevitable to screen blackgram genotypes that can withstand to high temperature and produce better yield even under adverse climatic conditions. Keeping this in view, the present investigation was carried out. Methods: Hundred blackgram genotypes were subjected to Temperature induction response technique, in which lethal temperature was standardized as 54°C for 3 hours and optimum induction temperature as 36-46°C. The selected genotypes from temperature induction response technique were further evaluated for biochemical traits using hierarchial clustering and principal component analysis. Result: The cellular level tolerance was assessed in blackgram genotypes using standardized lethal and optimum induction temperature. Based on the percent reduction in the seedling growth of induced over control and survival percentage, 27 blackgram genotypes were categorized as highly tolerant, 54 genotypes as moderately tolerant and 19 genotypes as susceptible. Biochemical characters such as antioxidant defence activity, lipid peroxidation and free radicals were analyzed in TIR induced 27 thermotolerant and 3 susceptible genotypes. The results indicated that all the traits such as total seedling length and antioxidant defence enzymes except malondialdehyde and free radicals showed a prominent increase under heat stress. Based on hierarchial clustering, 30 genotypes were clustered as 5 groups: tolerant (cluster-3,4), moderately tolerant (cluster-1,2) and susceptible (cluster-5). Principal component analysis showed that first five components showed 75.8% of total variation in control, whereas 63.3% of the total variance was covered by the first two PCs in heat induced conditions. The information generated from the study would help the breeders in developing heat tolerant varieties that perform better even under extreme high temperatures.