Molecular characterization of selected RILs derived from two low phosphorus tolerant rice genotypes
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Date
2018
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College of Post Graduate Studies in Agricultural Sciences, Central Agricultural University, Imphal
Abstract
Rice (Oryza sativa L., 2n=2x=24) is one of the most important cereal crop of the world. Phosphorous (P) being one the most important nutrients for growth and development, efficient phosphorus uptake capacity (PUP) and internal phosphorus use efficiency (PUE) is highly desirable. Production of rice in the North Eastern region of India is highly affected due to deficiency of P in soils resulting in low productivity. Therefore, it is necessary to develop rice genotypes which are tolerant to P deficiency. PSTOL1 is the only known gene successfully deployed in the field for better PUP in poor soils. Previously, data generated in our lab had identified two rice genotypes performing well under acidic soils having low P; LR23 (Sahbhagi Dhan; PsTOL1+) and LR26 (Chakhao Poreiton; PsTOL-). A recombinant inbred line (RIL) generated from LR23 X LR26 was phenotyped and genotyped with the following objectives: a) to characterize a set of top performing RILs with respect to morpho-physiological characters and b) to determine the parental allelic contribution in selected RILs with respect to SSR markers. A set of 1600 individuals (F5) were grown in the lowland acidic field and 17 different phenotypic traits were taken. On the basis of tiller number at 30 days and 60 days after transplanting, spikelet fertility %, 100 seed weight, total number of filled grains, a set oftop 20 performing lines were selected. These lines showed variation for the 17 phenotypic traits with lines like 172 (3) had higher panicle length and leaf area; line 34 (3) had higher tiller no. at 30 days, dry weight and total grain. Similarly, 81 (4) performed well for PUE and panicle number. Correlation analysis revealed that filled grain, 100 seed weight, dry weight and total grain were significantly correlated with grain yield (P value=0.57). Parental polymorphism survey performed using 157 SSR markers and 34 SNPs revealed 25 and 17 polymorphic markers, respectively. The STRUCTURE analysis to identify percentage ancestry (cut off >80%) in the 20 lines revealed that lines 33 (3), 34 (3), 65 (3), 122 (3), 81 (4), 59 (4) and 222 (3) are LR26 type whereas 114 (2), 188 (4) and 193 (1) are LR23 type. Chi-square test for goodness of fit revealed that HvssR02-14, RM527, snpOS0303, snpOS0304, snpOS0305, snpOS0306, BADH2 and Chalk5 showed significant values, suggesting preponderance of LR23 allele in markers 02-14 and chalk5 and LR26 allele other six markers. A sand based screening using Yoshida solution on these 20 lines along with the parents revealed significant differences in control and treatment conditions for all the six traits. Correlation for the sand culture data revealed significant association of total dry weight with total fresh weight and of root dry weight with total dry weight under normal phosphorus condition. Root dry weight under low P conditions was significantly correlated with total fresh weight. Thus, the selected top performing lines were distinct for both phenotypic and genotypic traits and therefore, can be used for further selection of best lines under lowland acidic soil conditions.