Evaluation of Genetic Diversity of Rice Landraces (Oryza sativa L.) in Yunnan, China

Abstract

Genetic diversity and geographic distribution of rice landraces in Yunnan, Southwest China were investigated based on 31 morphological traits (including Ding and Cheng's classification traits) using 6,121 accessions, 41 morphological traits and 12 polymorphic isozyme loci within the primary core collection of 912 accessions, and 20 microsatellite markers within the core collection of 692 accessions. Yunnan is the richest center of genetic diversity of rice (O. sativa L.) germplasm in China, in which indica varieties were derived from 108 counties in 16 prefectures and japonica varieties from 99 counties in 17 prefectures. Geographic distribution and diversity of six ecogroups and classification traits displayed clear differences. The average diversity indices of six ecogroups of rice landraces in Yunnan ranked as follows: javanica (1.2319), aman (1.1738), communis (1.1726), nuda (1.1618), aus (1.1371) and boro (0.9889), and the percentages were 3.6%, 43.9%, 32.1%, 18.1%, 2.1% and 0.2%, respectively. Lincang, Simao, Xishuangbanna and Dehong prefectures form the genetic and gene diversity center of rice landraces in Yunnan, especially Lincang Prefecture is not only the main genetic diversity center of rice landraces in Yunnan but also the diversity center of Ding's and Cheng's classification traits. South marginal paddy-upland rice region with Myanmar is the center of the gene diversity of rice landraces in Yunnan. A core collection from Yunnan rice landraces was identified based on morphological, isozyme and DNA variations, which have confirmed that Yunnan is the center of genetic differentiation of indica and japonica subspecies of Asian cultivated rice.

Assessment of the genetic diversity and population structure in temperate japonica rice germplasm used in breeding in Chile, with SSR markers

“…Despite its wide distribution, the relatively low genetic diversity can be attributed to its origin from a narrow gene pool marked by a more severe domestication bottleneck than indica or aus . Japonica rice cultivars has a mean PIC value of 0.65 in Yunnan (China) considered its center of diversification (Zeng et al, 2007), higher compared to the mean PIC value (0.47) obtained in this study.…”

Response of Rice under Salinity Stress: A Review Update

“…Morphological screening can be done using the parameters described as effective salinity indices like root length, shoot length, plant biomass, shoot Na + /K + ratio [38,39,125,126]. The morphological screening can be started at least after 10 days of exposure to saline solution for screening properly the tolerant genotypes from susceptible [37].…”

“…However screening for salinity tolerance based on agronomic characters may not prove to be practicable and fruitful technique because they are highly influenced by the environment. The understanding of the salt tolerance mechanisms and furthermore the assessment of salt tolerance is expected to be much more well defined by screening the genotypes at the biochemical level as undertaken by many scientists [75,81,112,119,125,126]. It provided an idea about the potential indicators of salt tolerance at the whole plant, tissue or cellular level.…”

Genetic structure revealed by a whole-genome single-nucleotide polymorphism survey of diverse accessions of cultivated Asian rice (Oryza sativa L.)

“…Analyses of molecular markers have also detected a considerable number of sequence variations in diverse cultivars (Sun et al 2002, Wang et al 1992, Yan et al 2007, Zeng et al 2007. Recent progress in rice genomics has enhanced our understanding of these natural variations, which are potential sources of useful genes for improving rice cultivars (Yamamoto et al 2009).…”