• SOMNATH BHATTACHARYYA

Articles written in Journal of Genetics

• Phosphate acquisition efficiency and phosphate starvation tolerance locus (PSTOL1) in rice

Phosphate availability is a major factor limiting tillering, grain filling vis-à-vis productivity of rice. Rice is often cultivated in soil like red and lateritic or acid, with low soluble phosphate content. To identify the best genotype suitable for these types of soils, P acquisition efficiency was estimated from 108 genotypes. Gobindabhog, Tulaipanji, Radhunipagal and Raghusail accumulated almost equal amounts of phosphate even when they were grown on P-sufficient soil. Here, we have reported the presence as well as the expression of a previously characterized rice gene, phosphate starvation tolerance locus (PSTOL1) in a set of selected genotypes. Two of four genotypes did not show any detectable expression but carried the gene. One mega cultivar, Swarna did not possess this gene but showed high P-deficiency tolerance ability. Increase of root biomass, not length, in P-limiting situations might be considered as one of the selecting criteria at the seedling stage. Neither the presence of PSTOL1 gene nor its closely-linked SSR RM1261, showed any association with P-deficiency tolerance among the 108 genotypes. Not only this, but the presence of PSTOL1 in recombinant inbred line (RIL) developed from a cross between Gobindabhog and Satabdi, also did not show any linkage with P-deficiency tolerance ability. Thus, before considering PSTOL1 gene in MAB, its expression and role in P-deficiency tolerance in the donor parent must be ascertained.

• Identification and analysis of low light tolerant rice genotypes in field conditions and their SSR-based diversity in various abiotic stress tolerant lines

The yield potentiality of kharif rice is not completely used even under well-irrigated agro-ecosystem, mainly due to lowirradiance by overcast cloud throughout the growing season in eastern India. We observed more than 50% yield reduction compared to theperformance of 100 high-yield genotypes for consecutive three years both under open and 30–35% reduced light intensity, mainly by 34%,25% and 12% reduction of panicle number, grains per panicle and test weight. As per the analysis of variance, genotypic varianceexplained 39% of the total yield-variation under shade with 58% heritability. Overall, the maintenance of equal panicle per plant in bothopen and shade has the highest association with shade tolerance. Purnendu, Sashi and Pantdhan19 showed less than 28% yield-reductionby maintenance or even by increasing grain numbers under shade and test weight. On the other hand, maintenance of an equal numberof panicle under both situations was the key to the tolerance of Bhasamanik, Sasarang, Rudra and Swarnaprabha. As compared toopen, we noticed the improvement of chlorophyll a and b under shade but saw a poor correlation with the shade tolerance index.Comparing the net photosynthesis rate (Pn) in eight genotypes, we found the best tolerant line ranked last with least Pn at low light intensity(\400 $\mu$mol m-2 s-1). We also identified diverse parental combinations between newly identified shade tolerant and abiotic stress toleranthigh-yielding rice lines following diversity analysis using 54 simple-sequence repeats. Thus, the selected tolerant lines from a large set ofgenotypes with different adjustment ability to keep up high yield under low light intensity can be used for physiological, molecular analysisas well as pyramiding of traits.

• Yield-enhancing SPIKE allele from the aus-subtype indica rice and its allele specific codominant marker

Improving spikelet number without limiting panicle number is an important strategy to increase rice productivity. In this study, a spikelet number enhancing SPIKE-allele was identified from the aus subtype indica rice, cv. Bhutmuri, which has an identical japonica like corresponding sequence including retrotransposon sequence, usually absent in indica genotypes, like IR64. An allele-specific singletube PCR-based codominant marker targeting an A/G single-nucleotide polymorphism (SNP) at the 3ˊUTR was identified for easier genotyping. The yield enhancing ability of the Bhutmuri-SPIKE allele carrying RILs and NILs over IR64-SPIKE allele carrying alleles was due to increased number of filled grains/panicle. More than three times higher abundance of SPIKE transcripts was observedin Bhutmuri and NILs carrying this allele compared with IR64 and its allele carrying NILs. Higher rate of photosynthesis at more than 900 µmolm-2s-1 light intensity and more than six small vascular bundles between the two large vascular bundles in the flag leaves of Bhutmuri and its allele carrying NILs were also observed. The identified SPIKE allele and the marker associated with it will be useful for increasing the productivity of rice by marker-assisted breeding.

• # Editorial Note on Continuous Article Publication

Posted on July 25, 2019