YUCCA基因家族在拟南芥胚胎发育过程中的表达模式研究

The Expression Patterns of YUCCA During Embryo Development in Arabidopsis

生长素作为重要的植物激素,在植物胚胎的形态建成和生长发育过程中起到关键的调控作用.依赖色氨酸的IPA途径是模式植物拟南芥中生长素合成的主要途径.以色氨酸为前体合成的IPA在YUCCA(YUC)的催化下生成IAA,这一过程也是生长素生物合成的限速步骤.拟南芥有11个YUC编码基因,目前对这11个YUC基因在植物胚胎发育过程中的表达模式还没有系统的研究.本文以Pro YUC:GUS(YUC1:GUS、YUC2:GUS、YUC4:GUS、YUC6:GUS、YUC8:GUS和YUC9:GUS)转基因植株为实验材料,观察在胚胎发育不同时期YUC基因的表达情况.结果表明:YUC1、YUC2和YUC4基因在拟南芥胚胎发育的后期(鱼雷期、拐杖期和成熟期)有极其微弱的表达;YUC6基因在拟南芥胚胎发育过程中没有表达;YUC8和YUC9在胚发育过程中有非常强的表达,其中YUC8主要在胚胎发育的三角胚时期、心形期和鱼雷期表达,而且在整个胚中表达,在拐杖期胚和成熟胚中YUC8特异在下胚轴和胚根中表达;YUC9在胚胎发育的球形期、三角胚时期和心形期有较强的表达,在胚发育的后期则在胚根有微弱的表达.这些结果表明拟南芥胚胎发育过程中存在生长素的本地合成,而且YUC8和YUC9是胚胎中参与生长素合成的主要基因.

Auxin plays crucial roles in the regulation of embryogenesis.Previous studies demonstrated that tryptophan （Trp）-dependent pathway is essential for IAA biosynthesis.IPA pathway has been considered the main process in the conversion of Trp to IAA in Arabidopsis.YUCCA （YUC） catalyzes the intermediate of IPA to IAA,which is the rate-limiting step of the IPA pathway.There are 11 YUC genes in Arabidopsis,so far their expression patterns during Arabidopsis embryogenesis are not clear.In this study,we use the transgenic plants of Pro YUC∶GUS （YUC1∶GUS,YUC2∶GUS,YUC4∶GUS,YUC6∶GUS,YUC8：GUS and YUC9∶GUS） to investigate the expression patterns of YUC genes during Arabidopsis embryonic development.Our results indicate that YUC1,YUC2 and YUC4 genes are weakly expressed in the embryo at the late developmental stages （torpedo stage,walking stick stage and mature stage）.YUC6 gene is not expressed during embryonic development.YUC8 and YUC9 genes are strongly expressed during embryonic development.YUC8 gene is expressed in the embryo at the triangular,heart and torpedo stages,whereas at later stages,its expression is restricted to the hypocotyl and radicle.YUC9 is strongly expressed in the whole embryo at the globular,triangular and heart stages,whereas at later stages its expression is restricted to the embryonic root.These results suggest that YUC8 and YUC9 are mainly involved in the biosynthesis of auxin during the embryonic development.