Grain quality characterization and molecular diversity analysis of aromatic rice (Oryza sativa L.) genotypes using SSR Markers
Loading...
Date
2018-11
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
College of Post Graduate Studies in Agricultural Sciences, Central Agricultural University , Imphal
Abstract
Rice is one of the world’s most important cereal crops. It belongs to grass family Poaceae (2n = 24). There are 25 species of genus Oryza, and only two species, namely Oryza sativa and Oryza glaberrima are cultivated. Aromatic rice constitutes a small but an important sub-group of rice. These are rated best in quality and fetch much higher price than high quality non-aromatic rice in international market. In spite of their importance, pace of improvement of this group of rice has been rather slow. In addition to other problems related with their cross compatibility with high yielding non-aromatic rice and high dependence of expression of quality traits on environmental factors, lack of information on various aspects of these rice too have contributed towards the slow pace of improvement of these rice. Quality rice are characterized by not only aroma but several other traits like grain length and width, elongation after cooking, amylose content, gelatinization temperature etc. Grain quality in rice is very difficult to define with precision as preferences for quality vary from country to country. The concept of quality varies according to the preparations for which grains are to be used. Although some of the quality characteristics desired by grower, miller and consumer may be the same, yet each may place different emphasis on various quality characteristics. The present investigation was carried out for grain quality characterization and genetic diversity analysis of 32 aromatic rice genotypes using SSR markers. A total of eight quality parameters related to grain were estimated and three nutritional estimation were also carried out using standard protocols. Maximum variations among the genotypes were observed for amylose content (AC), kernel length (KL), gel consistency (GC), carbohydrate content (CC) and protein content (PC). AC ranged from 2.97% to 20.60%, GC from 20.31 mm to 86.49 mm, CC from 29.83% to 82.18% and PC from 2.35% to 11.69%. In terms of nutritional quality analysis, Ja-Pnah (82.18%) followed by IC-465275 (81.55%) recorded the highest carbohydrate content. The other genotypes which were statistically at par with Ja-Pnah were IC-394788 (74.76%), IC-351517 (76.70%), IC-342368 (76.80%), Tai Sanghan (77.01%), Chakhao Amubi (77.38%), IC-464363 (77.53%), Faisenbuman Chakhao (78.01%), IC-342353 (78.93%), IC-464661 (79.66%) and IC- 464684 (79.95%). CT3-D-4 (11.69%) recorded the highest protein content %) which was statistically at par with Chakhao Poireiton (10.80%), CT3-D-6 (10.19%) and CT3-D-10 (10.51%) whereas IC-137342 (0.99%) recorded the highest fat content. Highest GCV was recorded for AC followed by PC suggesting selection based on the trait would be effective. The heritability recorded for the trait studied was high indicating that selection for quality traits is effective. The genetic diversity study was done using 24 SSR markers out of which 11 were polymorphic. The dendrogram generated by using Darwin 6.0.15 software identified three major clusters (I, II, and III). Cluster I is the largest cluster with 15 genotypes, Cluster II is the second largest cluster with 13 genotypes and Cluster III consisted of 4 genotypes. Among the polymorphic markers, number of alleles ranged from 2 (RM11, RM25 and RM 552), 3 (RM125), 4 (RM44, RM316,
RM215 and RM271) and 6 (RM447). Highest PIC value was recorded for RM447 (0.750) and lowest for RM125 (0.236). Heterozygosity (He) value ranged from 0.127 (RM484) to 0.782 (RM447). Maximum diversity was observed between IC-137401 and IC-342368 (0.98), followed by IC-342368 and IC-326284 (0.97). The genetic diversity studies conducted will help in further crop improvement programmes in identification and germplasm preservation.