| Bacterial leaf streak(BLS)is one of the most destructive diseases in rice.Many of researches have shown that BLS resistance in rice is quantitatively inherited,controlled by multiple quantitative trait loci(QTLs)of small effect.So,identifying the quantitative resistance loci(QRL)conferring the resistance to BLS in rice is very important for the understanding of the mechanism of quantitative resistance and for the breeding of resistant rice varieties.Until now,13 QTLs conferring the resistance to BLS have been founded in rice.Among them,11 QTLs have been founded by our lab.The present study focus on two QTLs(qBlsr5a and qBlsr3d).QBlsr5a has a relatively larger effect on the resistance,it can explain about 14.7%phenotype effect.The qBlsr5a have been fine mapped in 30kb region at the previous study.There are 3 annotated putative genes in this region(LOC_Os05gO1700,LOC_Os05g01710 and LOC_Os05g01730).According to results of sequencing and qRT-PCR,LOC_Os05g01700 and LOC_Os05g01710 are the most possibly candidate genes.The other QTL,qBlsr3d,was mapped in 3 chromosome,it can explain about 9.78%phenotype effect.According to the results of Cao(2014),the sub-CSSL containing qBlsr3d have been developed and the target gene is located within a 1250kb region between markers RM532 and 3DSSR12 on Chromosome 3.So the present study is focus on the functional verification of qBlsr5a and fine mapping of qBlsr3d.The research results are as following:1.By developed transgenic plants of RNAi for LOC_Os05g01710 in Nipponbare and MH86,compared the lesion length between the transgenic lines of 103,105 with Nipponbare,as well as 104 with MH86.The lesion length showed significant difference between103,104 and their control.However,there is no significant difference between 105 and NIP.Moreover,the lesion length in transgenic plants of gene knockout is shorter than that of H359.The results of qRT-PCR show that the expression level of LOC_Os05g01710 in H359 is higher than that of transgenic lines of RNAi in different times after inoculating.Thus,these data indicate that LOC_Os05g01710 is the candidate gene of qBlsr5a.2.By crossing highly susceptible cultivar H359 wih highly resistant NIL H359-BLSR3D and self-crossing,a F2 population containing 2663 plants were constructed.Using the two molecular markers on both sides of the target gene,RM532 and 3DSSR12,24 recombinant plants were selected and the corresponding F2:3 lines were developed.The homozygous plants in each selected F2:3 lines were picked out for inoculating.By genotyping the sub-CSSLs with molecular markers covering the qBlsr3d region and phenotyping the sub-CSSLs with artificial inoculation,the interval of qBlsr3d was narrowed to a region of 81 kb.3.By searching rice database,12 annotated putative genes,LOC_Os03g03470,LOC_Os03g03480,LOC_Os03g0349 LOC_Os03g03500,LOC_Os03g03510,LOC_Os03g03520,LOC_Os03g03530,LOC_Os03g03540,LOC_Os03g03550,LOC_Os03g03560,LOC_Os03g03570,LOC_Os03g03590,were founded in this region,and 3 putative genes(LOC_Os03g03500,LOC_Os03g03510 and LOC_Os03g03570)were finally sequenced.The result shows that three base differences in coding region between the two parents in LOC_Os03g03570,and it suggest that LOC_Os03g03570 is possibly the candidate gene of qBlsr3d. |
