拟南芥突变体uro的表型分析表明URO基因参与生长素调节的植物发育过程

在筛选拟南芥(ArabidopsisthalianaL.)叶突变体的过程中获得拟南芥uprightrosette(uro)突变体。uro为半显性突变体,因突变体在幼苗生长期莲座叶竖直生长而得名。对uro突变体的表型进行了详细的分析,结果表明uro突变不仅造成叶生长模式的改变,还出现多种其他异常表型。uro杂合和纯合突变体都表现出植物顶端优势的丧失,纯合突变体表现得更为严重。uro纯合突变体的一些二级分枝会被叶取代,这种叶的叶柄与叶片远轴面连接。突变体的花发育也有多种异常表型,主要表现为花瓣及雄蕊数目的改变、花器官的同源异型转化和不同花器官的融合。uro突变体茎软,细胞学水平分析表明突变体的内皮层组织发生增生,束间纤维发育及维管束分化受阻。顶端优势的丧失及维管组织的异常发育表明,URO基因可能参与生长素对植物发育的调节。pin1uro双突变体表型的分析表明,虽然双突变茎表型出现了两亲本表型的叠加,但双突变体的花却出现了新的表型,说明URO与PIN1基因在调节植物发育过程中具有部分遗传上的相互作用,这一结果进一步证明URO基因参与了生长素调节的植物发育过程。

Characterizations of the uro Mutant Suggest that the URO Gene Is Involved in the Auxin Action in Arabidopsis

The Arabidopsis gene UPRIGHT ROSETTE (URO) was previously identified as a leaf develop-mental regulator, as all rosette leaves of the semi-dominant upright rosette (uro) mutant grow uprightly atseedling stages. Here, we report more detailed phenotypic characterizations of the uro mutant and showthat the URO gene has multiple functions in plant development. In addition to its aberrant leaf-growingpattern, the uro mutant displayed pleiotropic phenotypes. Both uro/ and uro/uro plants showed a loss ofapical dominance, while such a phenotype in the uro/uro plants appeared more severe. Some secondarybranches of the uro/uro plants were replaced by leaves, for which petioles were attached to the abaxialside of leaves. Flowers often exhibited varying abnormalities, with altered numbers of petals and stamensand abnormally fused organs. Stems of the uro mutant were soft, which was caused by lacking interfas-cicular fiber. In addition, vascular differentiation in mutant stem was delayed. The loss of apical dominanceand the defects in vascular development and interfascicular fiber formation suggest that the URO functionmight be associated with auxin-mediated plant development. To provide more direct evidence whether theURO is involved in auxin action, we examined the URO function in auxin polar transportation pathway byanalyzing pinformed1 (pin1) uro double mutant. Phenotypes of the double mutant suggest that URO andPINFORMED1 (PIN1) have partial genetic interactions in plant development, which further supports thehypothesis that the URO gene may play an important role in the auxin regulatory pathway.