Physical Characteristics And Genetic Analysis Of Senescence Mutant T828 Of Foxtail Millet

Setaria italica is an annual grass,which can grow in high temperature and drought area,without effecting the yield.Because of these advantages and high in nutritional value,Setaria italica has been a major crop in northern China.Due to millet and its wild relatives green foxtail have the characteristics of being diploid,small genome(approximately 515Mb)and C4 photosynthesis,millet is being developed as a model of C4 plant and attracted the attention of many researchers at home and abroad.We obtained the senescence mutant T828,whose leaves dried up prematurely,from a mutant library of Yugul by using the chemical mutagen ethyl methane sulfonate.We compared T828 with Yugul among agronomic traits,photosynthetic pigment content and photosynthetic rate,and organise chemical analysis and transmission electron microscopy(TEM).In order to certify if the mutanted trait is control by a nuclei recessive monogenic or not,T828 mutant was crossed with SSR41 to build F2 population,which showed 3:1 segragation,proving that it was controlled by a nuclei recessive monogenic.Applied the method of BSA,mutant gene was located between the molecular mark of SiCAAS3056 and SSR3216 on the chromosome 3.The candidate gene was identified as Si021736m by DNA sequencing and alignment.The T828 began to appear premature trait at jointing stage(8-10 leaves),with its withering trait extending from the lower to upward until the whole plant dead eventually.So compared with Yugu 1,the plant height,neck length,panicle specialty and other agronomic traits all have significant changes in T828.The increased bite osmium number and larger volume,degraded chloroplast thylakoid and destroyed membrane could be observed with TEM.We also determined the photosynthetic pigments at various stages and found that the proportion of chlorophyll b was higher than chlorophyll a.The T828 mutated sites was located in the coding region of candidate gene Si021736m.A number of senescence-related genes have already been cloned in many species,such as rice,Arabidopsis,sorghum and wheat,but the relationship between oxalic acid metabolic pathway and premature phenotype has not been identified before.In this study,senescence-related gene was cloned from foxtail millet for the first time and identified as a key gene in oxalic acid metabolic pathway.The results provide a new idea for the study of the premature senescence mechanism in foxtail millet.