Kong Que, Ma Wei, Yang Haibing, Ma Guojie, Mantyla Jenny J, Benning Christoph
MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, MI 48824, USA.
Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824, USA.
J Exp Bot. 2017 Jul 20;68(16):4627-4634. doi: 10.1093/jxb/erx275.
WRINKLED1 (WRI1) is a key transcriptional regulator of fatty acid biosynthesis genes in diverse oil-containing tissues. Loss of function of Arabidopsis WRI1 leads to a reduction in the expression of genes for fatty acid biosynthesis and glycolysis, and concomitant strong reduction of seed oil content. The wri1-1 loss-of-function mutant shows reduced primary root growth and decreased acidification of the growth medium. The content of a conjugated form of the plant growth hormone auxin, indole-3-acetic acid (IAA)-Asp, was higher in wri1-1 plants compared with the wild-type. GH3.3, a gene encoding an enzyme involved in auxin degradation, displayed higher expression in the wri1-1 mutant. EMSAs demonstrated that AtWRI1 bound to the promoter of GH3.3. Specific AtWRI1-binding motifs were identified in the promoter of GH3.3. In addition, wri1-1 displayed decreased auxin transport. Expression of some PIN genes, which encode IAA carrier proteins, was reduced in wri1-1 plants as well. Correspondingly, AtWRI1 bound to the promoter regions of some PIN genes. It is well known that auxin exerts its maximum effects at a specific, optimal concentration in roots requiring a finely balanced auxin homeostasis. This process appears to be disrupted when the expression of WRI1 and in turn a subset of its target genes are misregulated, highlighting a role for WRI1 in root auxin homeostasis.
WRINKLED1（WRI1）是多种含油组织中脂肪酸生物合成基因的关键转录调节因子。拟南芥WRI1功能丧失导致脂肪酸生物合成和糖酵解基因的表达降低，同时种子油含量大幅减少。wri1-1功能丧失突变体的初生根生长减少，生长培养基的酸化程度降低。与野生型相比，wri1-1植株中植物生长激素生长素的共轭形式吲哚-3-乙酸（IAA）-天冬氨酸的含量更高。GH3.3是一个编码参与生长素降解的酶的基因，在wri1-1突变体中表达较高。电泳迁移率变动分析表明AtWRI1与GH3.3的启动子结合。在GH3.3的启动子中鉴定出了特定的AtWRI1结合基序。此外，wri1-1的生长素运输减少。一些编码IAA载体蛋白 的PIN基因在wri-1植株中的表达也降低。相应地，AtWRI与一些PIN基因的启动子区域结合。众所周知，生长素在根中特定的最佳浓度下发挥其最大作用，这需要精细平衡的生长素稳态。当WRI1及其一部分靶基因的表达失调时，这个过程似乎会被破坏，这突出了WRI1在根生长素稳态中的作用。
