Function of HRBs and interaction of HRB1 with PP7 in blue light-mediated stomatal opening

智力优势：干旱是限制作物产量的主要环境因素之一。植物叶片的气孔位于表皮，周围有一对保卫细胞，可以吸收光合作用中的二氧化碳，并通过蒸腾作用失去水分。蓝光调节气孔开度，蓝光/紫外光A吸收光的趋光素和隐花色素可感受到这些信号。将蓝光感知与气孔开放反应联系起来的信号成分在很大程度上是未知的，对红蓝(HRB)突变体特别敏感的信号成分是人们特别感兴趣的。HRB突变体最初被分离出来是因为它们在红光和蓝光下的下胚轴较短的表型。有趣的是，在HRB突变体中，蓝光诱导的气孔开放反应也受到了损害，突变植株对脱水的抗性更强，失水和气孔开度都有所减少。HRB突变体的强气孔表型可能是由于红光和蓝光信号都受到了损害，因为红光经常增强蓝光反应。HRB1基因已被分子克隆，并编码一个核ZZ型锌指蛋白。HRB1通过其ZZ型锌指结构域与磷酸酶7(或PP7)物理上相互作用，PP7是一种核丝氨酸/苏氨酸磷酸酶，也是蓝光信号的正调控因子。本项目的目标是了解HRBS在蓝光调节气孔开度中的作用。我们将研究HRB1如何在趋光性和隐色素信号通路中发挥作用，以及HRB1在hrb2和hrb3背景下的功能。还将深入研究HRB1和PP7如何在体内和遗传上相互作用，以及它们相互作用的性质。广泛的影响：这项研究将为本科生、研究生和博士后提供获得重要研究经验的极好机会，最重要的是，培养他们批判性分析和解决科学问题的能力。过去，包括非洲裔美国人和西班牙裔学生在内的不同本科生群体曾在这个实验室进行过研究。13名本科生中有6名来自全校生命科学暑期本科生研究项目。这些学生在全国范围内被招募，在校园里呆上10周，参与重大研究项目和每周一次的研讨会系列，并在总结研讨会上向他们的同行和导师展示他们的研究成果。在该项目的具体目标I中，概述了针对本科生的具体培训计划，范围从生理学、遗传学到分子研究。在更广泛的层面上，该项目将为工程气孔活动打开新的可能性，并帮助植物在干燥中生存下来。除了蓝光外，气孔开度还受到其他环境信号的调节，如干旱。考虑到HRB植物仍可能对ABA(一种众所周知的干旱信号)做出反应，这些植物在水分限制条件下应该同时享有结构性保护和诱导保护的优势。

Intellectual Merit: Drought is one of the major environmental factors that limit crop yield. The stomatal pores of plant leaves, situated in the epidermis and surrounded by a pair of guard cells, allow CO2 uptake for photosynthesis and the loss of water through transpiration. Blue light regulates the stomatal aperture and the signals are perceived by the blue/UV A light-absorbing phototropins and cryptochromes. The signaling components that link the perception of blue light to the stomatal opening response are largely unknown, and hypersensitive to red and blue (hrb) mutants are of particular interest. The hrb mutants were initially isolated for their short hypocotyl phenotype under red and blue light. Interestingly, the blue light-induced stomatal opening response is also impaired in the hrb mutants, and the mutant plants are more resistant to dehydration and show reduced water loss and stomatal aperture. The strong stomatal phenotype of the hrb mutants may be due to impairment in both red and blue light signaling since red light often enhances blue light responses. The HRB1 gene has been molecularly cloned and encodes a nuclear ZZ-type zinc finger protein. HRB1 physically interacts with phosphatase 7 (or PP7), a nuclear serine/threonine phosphatase and a positive regulator of blue light signaling, through its ZZ-type zinc finger domain. The goal of this project is to understand the roles of HRBs in blue light regulation of stomatal aperture. How HRB1 functions within the phototropin and cryptochrome signaling pathways and the function of HRB1 in hrb2 and hrb3 backgrounds will be investigated. How HRB1 and PP7 interact in vivo and genetically and the nature of their interaction will also be thoroughly studied.Broader Impacts: This research will provide excellent opportunities for undergraduates, graduate students, and postdoctoral fellows to gain significant research experiences, and most importantly, to develop their ability to critically analyze and solve scientific problems. A diverse group of undergraduates including African American and Hispanic students have conducted research in this lab in the past. Six of the 13 undergraduates are minorities from a campus-wide life science summer undergraduate research program. The students are recruited throughout the country, spend 10 weeks on the campus, participate in major research projects and a weekly seminar series, and present their research results to their peers and mentors at a concluding symposium. In specific aim I of this project, a specific training plan was outlined for the undergraduates, ranging from physiological, genetic, to molecular studies. On an even broader level, this project will open new possibilities to engineering stomatal activity and help plants to survive desiccation. The stomatal aperture is also regulated by other environmental cues such as drought in addition to blue light. Given that hrb plants may still respond to ABA, a well-known drought signal, these plants should enjoy the advantages of both constitutive and induced protection under water-limiting conditions.