QTL Analysis Of Salt And Alkali Tolerance In Japonica Rice

Rice is not only the main food crops in the world,but also the world’s 3.5billion population survival rations, So to improve the yield of rice to ensure food security is of great significance. In recent years, industrial pollution,unreasonable irrigation and fertilization, and early spring water and fresh water resources shortage and other reasons,resulting in the salinization of soil has become increasingly worse.Therefore, research on the saline-alkali tolerance of rice by molecular means, breeding saline-alkali tolerance varieties of rice is an important way to improve saline-alkali area rice yield, is of great significance to promote the sustainable development of rice production.The recombinant inbred line(F6:7 RIL) population derived from the cross “Dong-nong 425×Chang-bai 10” were used in the study. Salt and alkali stress were carried out at the seedling stage and field growth period, and the salt and alkali tolerance traits were analyzed by QTL. in order to further reveal the genetic mechanism of salt tolerance of rice and alkali tolerance, and provide scientific basis for rice saline-alkali tolerance molecular marker assisted breeding.The main results were as follows:(1) SNC, SKC, SNK, DLR, SST/SAT and SDS were significant differences, but RNC,RKC and RNK has no significant difference between the two parents at the seedling stage under salt or alkali stress.ML, PN, GN, PW, SP, SS, GW and PW decreased obviously under salt or alkali stress compared with those of traits under natural conditions,but WN increased atfield growth period.(2) There wassignificant or highly significant positive correlationwith SNC and SKC as well as SNC and SNKat the seedling stage under salt or alkali stress, it indicate that the shoots of transport of the Na+ and K+ were no selective; there washighly significant positive correlationwith RNC and RKCas well as RNC and RNK at the seedling stage under salt or alkali stress, it indicate that the uptake of Na+ and K+ in roots were no selective;there wassignificant positive correlation with SNC and DLRas well as SNCand SST/SAT,there washighly significant negative correlation with SNC and SDS, it indicate that SNC more, DLR and SST/SAT is high,SDS is short,the rice tolerance to saline-alkali worse.There wassignificantpositive correlationwith PW and GN as well as PW and SSatfield growth period, it indicate that GN and SS is the important factor onyield under saline-alkali stress.(3) The use of QTL Ici Mapping v3.3 drawing software, F6:7 RIL 180 populations were used as experimental materials, Constructed with 102 SSR markers, a total length of 1915.05 c M, the average distance between the markers for genetic mapping of 18.77 c M. There are 16 markers showing distorted segregation in the RIL group(p≤0.01), accounting for 15.68% of the total to mark.(4) Using QTL Ici Mapping v3.3 analysis by the complete interval mapping method were conducted with LOD=2.5 as the threshold for QTL detection of RIL populations. Seedling detected 29 QTL Under salt or alkali stress. The contribution rate of more than 10% of the q SRNC3-1, q ASNC2, q ARNC3, q ARNK3, q ASAT3, q ASAT7, q ASDS3 and q ASDS7. The natural conditions of the field growth stages detected 13 QTL, the contribution rate of more than 10% of the q ML1; Salt and alkali stresses detected 31 QTL, the contribution rate of more than 10% of the q SML1, q SML6, q SGN1, q SSP1, q SSS11, q SGW9, q SPW11, q SRML11, q SRWN3, q SRSP3, q SRGW9, q AGN12, q ARWN3 and qARGN12.(5) 29 QTL were detected under salt or alkali stress at the seedling stage, only 3 QTL on the same or adjacent intervals, the rest are located in different position of chromosome, it indicate that SNC, SKC, SNK, RNC, RKC, RNK, DLR, SST/SAT and SDS of traits genetic overlap is very small, the genetic may be independently inherited salt or alkali tolerance at the seedling stage. 31 QTL were detected under salt or alkali stress at the field growth period, only 2 QTL on the same or adjacent intervals, the rest are located in different position of chromosome, it indicate that ML、PN、WN、GN、SP、SS、GW and PW of traits genetic overlap is very small, the genetic may be independently inherited salt or alkali tolerance at the field growth period in rice.(6) A total of 60 QTL were detected under salt or alkali stress at the seedling stage as well as at the field growth period. The seedling salt tolerance traits and field growth stage of salt tolerant trait of the detected QTL is not positioned same or adjacent interval on the same chromosome interval. The seedling alkali tolerance traits and field growth stage of alkali tolerant trait of the detected QTL is only 2 QTL positioned adjacent intervals on the same chromosome,because the genetic overlap is small between two period, so genetic control seedling and field growth period of saline-alkali tolerance related traits may be independent of each other.