Identification Of QTLs Associated With Nitrogen Use Efficiency At Seedling Stage Using Cssls In Rice

Rice is one of the main food crops and the staple food for most people in China.With the growth of our country’s population,the demand for grain is also increasing.Therefore,the importance of high yield of rice is beyond any doubt.Fertilization is one of the most important part in the process of rice production,it is also the cost that cannot be ignored.Nitrogen fertilizer has its irreplaceable position in all of the fertilizer.However,over the past years,excessive use of nitrogen fertilizer has caused many wastes and has led to immeasurable environmental pollution.Therefore,breeding of high-yield rice varieties with high nitrogen use efficiency is the key to solve this problem.In this study,we used a set of chromosome segment substitution line with Guangluai4 as the recipient parent and Nipponbare as the donor parent to map the QTLs controlling the nitrogen use efficiency(NUE)and total nitrogen accumulation(NA).We also analyze the relationship between nitrogen use and seedling growth.The main results are as follows:1.As a result,13 QTLs related to nitrogen use efficiency were mapped,they were qNUE3-1,qNUE3-2,qNUE3-3,qNUE3-4 on chromosome 3,qNUE5 on chromosome 5,qNUE6-1,qNUE6-2 on chromosome 6,qNUE7-1,qNUE7-2 on chromosome 7,qNUE8-1,qNUE8-2,qNUE8-3 on chromosome 8,qNUEll on chromosome 11.In these QTLs,only two of them had positive additive effects,they were qNUE3-4 and qNUE7-1.In addition to the two nitrogen use efficiency QTL,qNUE3-3 and qNUE6-2 are coincident with the previous studies,the remaining QTLs had not been reported before.2.Two QTLs related to total nitrogen accumulation were mapped,they were qNAll on chromosome 11 and qNA12 on chromosome 12.Both of them had negative additive effect and had not been reported before.3.We found that the correlation between NA and two seedling growth characters(seedling height and seedling weight)were both very significant.The correlation between NUE and seedling weight was also very significant.This meant the traits of nitrogen use could affect the growth of seedlings.