The Gene Cloning And Function Study Of A Short Root Mutant Osksr4in Rice

β-ketoacyl-ACP synthase plays an important role during the fatty acids synthesis and thedevelopment of rice roots. Located on chromosome6, OsKSR4has been cloned to control riceroot length. OsKSR4has seven exons and six introns, and encodes a49KDa of β-ketoacyl-ACPsynthase with465amino acids. There is a point mutation (Câ†'T) at770bp after the ATG.Gene mutations affects the growth of rice root severely. The root length of mutant is shorterthan15%of wild-type, that of lateral root and adventitious root are shorter, too.The tillers numberand pollen viability are reduced, so are setting rate, yield and the width of leaf. There is a largeamount of active oxygen in meristematic zone, and the length is just60%of wild type. Althoughthe length of the root tip cells is shorter, the cell arrangement of elongation zone and mature zoneare more regular. These results suggest that it is the acculation of active oxygen in meristematiczone that affects the elongation of elongation zone cell and cell development of maturation zonecell.Semi-quantitative RT-PCR and GUS staining analysis showed that OsKSR4were expressedin roots, stems, leaves, flowers and seeds. Subcellular loealization of P35S::OsKSR4::GFP locatedon the plastid of onion.Lipid content determination and composition analysis experiments confirmed that the genewas not only involved in the regulation of the synthesis pathway of fatty, but also effecting fattyacid desaturation pathway and the content of sterols. However, it still needs to do further study asthe way of regulation is not clear. We guess that the regulation approachs of KASI are differentbetween the monocot and dicot plants on the basis of different performance beween Osksr4mutantwhich has normal leaf and short root and Arabidopsis kasI mutant which has been found recently.