Genetic Diversity of Main Inbred Indica Rice Varieties Applied in Guangdong Province as Revealed by Molecular Marker

Genetic diversity of 299 inbred indica rice varieties, including 33 introduced varieties, applied in Guangdong Province of China were assessed using 20 ILP (intron length polymorphism) and 34 SSR (simple sequence repeat) markers. Totally, 154 loci were screened for the 299 varieties, with the average number of alleles (Na), rare alleles (Nr), and polymorphism information content (PIC) scored at 3.4, 0.7 and 0.32, respectively. The Nei's genetic distance (GD) was estimated ranging from 0 to 0.7529 with an average of 0.4797. There was no significant difference of Na, Nr, PIC or GDs between the introduced and local varieties. Neighbor-joining (NJ) analysis showed that the 299 varieties failed into three main distinct groups, and the 33 introduced varieties were distributed over all the groups or subgroups. Model-based cluster analysis demonstrated that only 73 (24.4%) of the 299 varieties and 7 (21.2%) of the 33 introduced varieties could be distinctly classified into the three groups. Analysis of molecular variance showed that within the groups divided by NJ analysis, the genetic variations revealed by ILP, SSR and these two combined were 7.7%, 5.6% and 6.6%, and within the groups divided by region (Guangdong local and the introduced varieties), the genetic variables were 2.1%, 4.6%, 5.4%, respectively. These results suggested that the genetic diversity of the 299 inbred rice varieties in Guangdong Province was low, simultaneously relationship among varieties was poor and close in all kind of groups. Hence, it is very necessary to extend the genetic diversity during the breeding and selection practical procedure.