Map-based Cloning And Preliminary Functional Analysis Of Rice Panicle Degenerative Gene ATAP1

Spikelet degeneration is a common phenomenon in rice breeding,which significantly reduce the spikelet volume and grain number per spike,and then affect rice yield.In this study,we attempted to isolate a panicle degeneration candidate gene ATAP1 from a tissue culture-originated spikelet degeneration mutant atapl(atypical panicle degeneration 1)using the map-based cloning strategy.Through the construction of genetic mapping population,the candidate gene ATAP1,a farnesyltransferase subunit beta(FSB)encoding by gene LOC_Os01g53600,was finely mapped,and was subsequently confirmed by transgenic experiment.In addition,we analyzed preliminarily the gene function.The main results are as follows:1.Compared with the wild type,the mutant atapl showed the reduced plant height,the degenerated spikelets,the prolonged heading data,and increased ineffective tillers.There are varying degrees flower degeneration among tillers,resulting in a serious reduction of seed setting rate and grain number per panicle,however,in an unexpected impact on 1000grain weight increment.2.Using the strategy of map-based cloning,ATAP1 was finely delimited in the 141Kb range flanked by the markers of Z10 and Z12 on the long arm of chromosome 1,This region includes 15 ORFs.Sequencing showed that there is a 56bp deletion sharing by two ORFs.The deletion occurred on the first exon of gene LOC_Os01g53600,or on the promoter region of LOC_Os01g53610.3.By constructing complementary and knockout transgenic plants,the knockout plants to candidate gene LOC_Os01g53600 showed the similar spike degeneration phenotype as the mutant,indicating that the LOC_Os01g53600,a farnesyltransferase subunit beta(FSB),is the target gene.4.The mutation on Arabidopsis homologous genes ERA1 is suggestted cause ABA responses changes.We investigated ABA content between the mutant atapl and wild type,and found that the amount of total ABA and the respective active components tABA and cABA in mutant were significantly increased compared with the wild type.We further analyzed the expression levels of ABA synthesis and oxidation genes,and found that the expression levels of ABA synthesis genes AAO and ABA2 increased significantly,while the expression levels of ABA oxidation genes ABA8oxl decreased significantly.Investigate the expression levels of LEA3,LEA7,LEA22,LEA28 and DREB genes relate to response ABA and drought stress,it was found that the expression levels of these genes were significantly increased,consistent with the results in Arabidopsis.5.The farnesylation of protein is connected farnesyl to the carboxyl terminal of protein under the activation of farnesyltransferase(FTase),which is a post-translated lipid modification and may be involved in the regulation of multiple growth and development processes of plants.The rule of gene ATAP1 in the regulation of panicle development remains unclear and needs to be investigated.