Mapping Of QTLs Controlling Mature Seed Callus Induction And Differentiation Ratio In Rice

Rice(Qryza sativa L.) is one of the most important food crops in China. Improving breeding technique is an important approach to enhance the rice production and quality. In recent years, molecular breeding is a new breeding technique, which is the complement of traditional breeding technique.According to callus induction ratio and green plantlet differentiation ratio of rice mature seed, new lines were obtained by transformation technology, which has significance in molecular breeding of rice. And the efficiency of rice genetic transformation mainly depends on in vitro tissue culture and regeneration. Due to differences in genotype, the callus induction ratio and green plantlet differentiation ratio of Indica and japonica rice are very different. Compared with japonica rice, indica rice is difficult to tissue culture, thus impeding genetic transformation. So it is necessary to find out the genetic basis of different culturability between indica and japonica nce.Recent years, research shows that the efficiency of genetic transformation in rice was controlled by quantitative trait loci (QTLs). So identification of QTLs controlling callus induction ratio and green plantlet differentiation ratio in rice can not only elucidate its mechanism at the molecular level, but also have great significance to development quantitative trait molecular breeding, and improve rice varieties and the efficiency of rice genetic transformation. In our previous studies, in order to locate and identificate the QTLs controlling the culturability in rice mature seed, a set of 113 chromosome segment substitution lines(CSSLs) were used as materials, developed by the indica 9311 and japonica Nipponbareas as the recipient and donor parent, respectively. Through the statistics of callus induction ratio and green plantlet differentiation ratio in rice mature seed culture, the related QTLs were mapped by multiple linear regression analysis.In this study, a total of 41 QTLs mapped for callus induction ratio and green plantlet differentiation ratio were mapped by using rice chromosome segment substitution lines. The contribution rate of additive effects in 21 QTLs reach to 40%. Among them,16 and 9 QTLs were respectively mapped for callus induction and differentiation ratio in MS II culture system; Respectively,6 and 10 QTLs were mapped in N6D2 culture system. The qMIR4-1 and qNIR4-1 for induction ratio were located in chromosome 4, in section of 35,398,407-35,863,200 bp; qMIR5-2 for induction ratio and qMDR5-1 for differentiation ratio were both located in chromosome 5, in section of 2,208,395-3,519,762 bp; qMIR8-2 and qNIR8-1 for induction ratio were in chromosome 8 with positive additive effect value. This study is providing a basis for improving the indica mature seed culturability, which is also preparing for rice molecular breeding research.