Genetic Analysis And Cloning Of Pale Green Leaf Mutant(pgl1)Gene In Setaria Italica

Photosynthesis is one of the key factors to determine crop yield.,but also the color of leaves largely determines the efficiency of photosynthesis.In this study,we used of chemical mutagen ethyl methane sulfonate(ethyl methylsulfonate,EMS)to induce Setaria Yugu l,and we got the mutant pgl1 with pale green leaves throughout the growing period.Compared with normal color variety Yugu1,the mutant pgl1 performed pale green in different degrees,setting rate and grain weight decreased slightly.Content of chlorophyll content(Chl)and carotenoids(Caro)were significantly lower than that of wild type.Comparative analysis of chloroplast ultrastructure showed that:the grana were irregular,only a few thylakoids of each grana stacked pile,and the number of osmiophilic particles significantly increased compared with wild-type.Photosynthetic performance of the mutant was not affected.Genetic analys showed that:pgll mutation was controlled by a single recessive gene.In this study,we used the F2 recessive population to fine mapping and by sequence analysis of its results,we concluded:mutant pgll was changed magnesium chelate D subunits of a single base.The mutational pgll had a single base change from T to A at position 900bp which is located at 5th exon.This mutation led to an amino acid change from Phe(F)to Leu(L)at position 300aa.We used real-time RT-PCR method to analyze the expression at different times of target gene ChlD and magnesium chelatase related gene(magnesium ions and chelating H subunit I and subunit ChlH ChlI).We concluded that expression levels of ChlD gene did not differ significantly in the seedling stage,booting and heading stages.The expression levels of ChlH and ChlI genes had no significant change in the seedling stage and booting stage,but in the heading times ChlH and Chll are significantly higher than that of wild-type.We presumed single nucleotide change in ChlD of pgll mutant did not lead to changes in expression level.At heading times,ChlD affect expression of ChlH and Chll gene resulting in higher expression.