Cloning And Preliminary Functional Analysis Of Grain Shape Locus QGS7 And Hairy Leaf Gene HL1 In Rice

Rice grain shape is one of the important indicators affecting the grain weight.Meanwhile it’s closely related to rice appearance quality,cooking quality and nutritional quality.So the rational grain shape has the important theoretical significance and practical value in breeding high yield and quality rice.This study used a japonica variety Longliheinuo-Dwarf(small grain)and an indica variety N-643(large grain)as the parental lines for genetic analysis through hybridization,backcrossing and selfing.In the early study,qGS7 was finely mapped to a 52.8 kb region between markers In13 and C4-47 on the chromosome 7 and 4 candidate genes with effective mutations were obtained by gene prediction and sequence analysis.On these basis,RT-PCR analysis was performed on the different spike tissues of the paired NILs.The expression of LOC_Os07g42410 and LOC_Os07g42450 was in accordance with the development of spikelets.EP2/DEP2/SRS1 was reported as the erect panicle small round gene and had the same region with LOC_Os07g42410.So LOC_Os07g42410 was identified as the candidate gene of qGS7 for further analysis.Through SNP diversity analysis of rice varieties with different grain shape,SNP2(single nucleotide T deletion)was identified as the core mutation site,which leading to the premature translation termination.But this mutation site was different from the reported.The investigation of agronomic traits in the paired NILs showed that qGS7 only affected the partial traits of plants and had no significant effect on the yield per plant.Trichome is the ecological adaptability of plants in response to various environmental stresses.It can reduce the loss of water and heat in plants,mechanical damage and insect pests,pathogen attack.Therefore the research of trichome development and formation mechanism has the important scientific significance and application value.This study used an indica variety SWWR(piliferous)and a japonica variety Nipponbare(glabrous)as the parental lines.In the early study,LOC_Os06g44750 which on the chromosome 6 was identified as the hairy leaf gene HL1 and transgenic rice plants were constructed.T1 generation seed of the over-expression transgenic plants and T0 generation seedling of the complementary-expression transgenic plants were obtained.On these basis,we verified the previous result of fine-mapping,10 recombinant individuals and 3inconsistent individuals were identified,which covering the early region through linkage analysis.PCR positive identification and phenotype observation were performed on transgenic rice plants,there were no trichomes on the leaf of positive plants in T1 generation of the over-expression transgenic plants,but there were trichomes with different density on the leaf of positive plants in T0 and T1 generation of the complementary-expression transgenic plants.CRISPR point mutation vector was constructed for the follow-up study of HL1.