Genetic Analysis And Preliminary Gene Mapping Of Clustered Spikelets In Rice

Germplasm resource is also known as varieties or genetic resources, which refers to the basic material for breeding new varieties. It is the breeding material basis and breeders of the basic materials. Breeding is essentially the reprocessing of germplasm resources. High-yield rice breeding is one of the main objectives pursued by breeding workers. Over the past decades, the roles of fine varieties in the world of Nongmu Yu increase output is about 20% to30%. However, with the development of commercializetion of agriculture, many local varieties are lost. After the mid-80s, China and even the world's major countries in the new breeding work is at the difficult stage of "climbing" stage. Crop yields, quality and resistance has few breakthrough. The reason is mainly that this parent materials genetic base is narrow and lack of good new germplasm resources. Therefore, exploring new germplasm resources, selecting high-yielding crop varieties has great significance. A number of mutant materials don't have integrated traits, but have some advantage individual traits which can solve the problem of the parent material genetic narrow. In recent years, with the emergence of molecular marker techniques, in order to explain the important agronomic traits (such as yield, quality, resistance, etc.) provides a strong means, and bring hope for people to develop excellect new rice varieties.Clustered spikelets rice is a mutant material which is belong to spikelets, Multigrains Rice is one kind of clustered spikelets rice. Clustered material from different sources in anatomy, genetics and gene mapping studies have been reported, but there are not reports about this kind of Multigrains Rice been mapped by SSR markers. To make further research of Multigrains Rice and practice to breeding, Genetic analyses and gene mapping of the F1, F2 segregating population derived from four crosses-- Oryza sativa Japonica/Multigrains Rice, R8258/Multigrains Rice, H103/Multigrains Rice, R99 / Multigrains Rice, have been researched. The main results were presented as follows:1. Genetic analysis of clustered trait:Through field investigation and genetic analysis in four genetic populations, as Oryza sativa Japonica/Multigrains Rice, R8258/Multigrains Rice, H103/Multigrains Rice, R99 / Multigrains Rice, we found that F1 is incomplete dominant, F2 is according to three to one by X2 analysis, so this trait was controlled by an incomplete dominant gene. The Cl gene in the four groups followes the laws of Mendelian single-gene genetic segregation.2. Preliminary Gene Mapping of Cl:695 pairs simple sequence repeat(SSR)markers were used for PCR amplification during parents, domiant and recessive gene pool. We obtained nine pairs of polymorphic primers. F2 populations including Oryza sativaJaponica/Multigrains Rice, in which there are 210 individuals, and R8258/Multigrains Rice, in which there are 919 individuals, were analyzed with the nine pairs of polymorphic primers. By Oryza sativaJaponica/Multigrains Rice F2 population, Cl was mapped on chromosome 6 between the SSR marker RM162and RM454, with the genetic distance of 4.32cM and 3.85cM, respectively. Furthermore, we mapped Cl by R8258/Multigrains Rice population between the SSR marker RM7434 and RM20300 on chromosome 6 with the genetic distance of 4.29 cM and 1.19 cM, respectively.