Davis Thomas C, Jones Daniel S, Dino Arianna J, Cejda Nicholas I, Yuan Jing, Willoughby Andrew C, Kessler Sharon A
Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN, 47907, USA.
Purdue Center for Plant Biology, Purdue University, West Lafayette, IN, 47907, USA.
Plant Reprod. 2017 Dec;30(4):185-195. doi: 10.1007/s00497-017-0313-2. Epub 2017 Nov 20.
MLOs in Plant Reproduction. The MILDEW RESISTANCE LOCUS-O (MLO) protein family, comprised of 15 members, plays roles in diverse cell-cell communication processes such as powdery mildew susceptibility, root thigmomorphogenesis, and pollen tube reception. The NORTIA (NTA, AtMLO7) gene is expressed in the synergid cells of the female gametophyte where it functions in intercellular communication with the pollen tube. Discrepancies between previously published promoter::GUS and promoter::gene-GUS constructs expression patterns led us to explore the regulation of NTA expression. Here we found via NTA::gNTA-GUS truncations that sequences within the NTA gene negatively regulate its expression in the stomata and carpel walls. This led to the hypothesis that other MLO family members may also have additional regulatory sequences within the gene. MLO::gMLO-GUS constructs were examined for each family member focusing specifically on flowers in order to determine whether other MLOs could play a role in reproductive cell-cell communication. Notably, several MLOs were expressed in the pollen, in the stigma, in the pollinated style, and in the synergids and central cell. These findings indicate that other MLOs in addition to NTA could play a role in reproduction. Previous studies on the MLO family showed that phylogenetically related MLOs had redundant functions in powdery mildew infection and root thigmomorphogenesis; however, MLO expression in reproductive tissues did not strictly follow phylogenetic relationships, indicating that MLOs from different evolutionary origins may have been recruited for function in sexual reproduction.
植物繁殖中的MLOs。由15个成员组成的抗白粉病基因座O（MLO）蛋白家族，在多种细胞间通讯过程中发挥作用，如对白粉病的易感性、根的触变形态发生以及花粉管识别。NORTIA（NTA，AtMLO7）基因在雌配子体的助细胞中表达，在那里它参与与花粉管的细胞间通讯。先前发表的启动子::GUS和启动子::基因 - GUS构建体表达模式之间的差异促使我们探索NTA表达的调控。在这里，我们通过NTA::gNTA - GUS截短发现，NTA基因内的序列在气孔和心皮壁中负调控其表达。这导致了一个假设，即其他MLO家族成员在基因内可能也有额外的调控序列。针对每个家族成员检查了MLO::gMLO - GUS构建体，特别关注花，以确定其他MLO是否能在生殖细胞间通讯中发挥作用。值得注意的是，几个MLO在花粉、柱头、授粉的花柱以及助细胞和中央细胞中表达。这些发现表明，除了NTA之外，其他MLO也可能在繁殖中发挥作用。先前对MLO家族的研究表明，系统发育相关的MLO在白粉病感染和根的触变形态发生中具有冗余功能；然而，MLO在生殖组织中的表达并不严格遵循系统发育关系，这表明来自不同进化起源的MLO可能已被招募用于有性生殖中的功能。
