Wenzel Carol L, Schuetz Mathias, Yu Qian, Mattsson Jim
Department of Biological Sciences, Simon Fraser University, 8888 University Drive, Burnaby, BC, V5A1S6, Canada.
Plant J. 2007 Feb;49(3):387-98. doi: 10.1111/j.1365-313X.2006.02977.x. Epub 2007 Jan 1.
Genetic evidence links the Arabidopsis MONOPTEROS (MP) and PIN-FORMED1 (PIN1) genes to the patterning of leaf veins. To elucidate their potential functions and interactions in this process, we have assessed the dynamics of MP and PIN1 expression during vascular patterning in Arabidopsis leaf primordia. Both genes undergo a dynamic process of gradual refinement of expression into files one to two cells wide before overt vascular differentiation. The subcellular distribution of PIN1 is also gradually refined from a non-polar distribution in isodiametric cells to strongly polarized in elongated procambial cells and provides an indication of overall directions of auxin flow. We found evidence that MP expression can be activated by auxin exposure and that PIN1 as well as DR5::GUS expression is defective in mp mutant leaves. Taken together the results suggest a feedback regulatory loop that involves auxin, MP and PIN1 and provide novel experimental support for the canalization-of-auxin-flow hypothesis.
遗传学证据表明，拟南芥中的MONOPTEROS（MP）基因和PIN-FORMED1（PIN1）基因与叶脉的形成模式有关。为了阐明它们在此过程中的潜在功能及相互作用，我们评估了拟南芥叶原基维管模式形成过程中MP和PIN1表达的动态变化。在明显的维管分化之前，这两个基因都经历了一个将表达逐渐细化为一到两个细胞宽的条带的动态过程。PIN1的亚细胞分布也从等径细胞中的非极性分布逐渐细化为伸长的原形成层细胞中的强极性分布，并为生长素流动的总体方向提供了指示。我们发现有证据表明，生长素处理可激活MP的表达，并且在mp突变体叶片中，PIN1以及DR5::GUS的表达存在缺陷。综合这些结果表明，存在一个涉及生长素、MP和PIN1的反馈调节环，并为生长素流管道化假说提供了新的实验支持。
