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，允许光合作用吸收CO2，并通过蒸腾作用损失水分。蓝光调节气孔开度，并且信号被吸收蓝光/UV A光的向光蛋白和隐花色素感知。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，对红蓝超敏（hrb）突变体特别令人感兴趣。hrb突变体最初是根据其在红光和蓝光下的短下胚轴表型分离的。有趣的是，蓝光诱导的气孔开放反应在hrb突变体中也被削弱，突变体植物对脱水的抗性更强，水分流失和气孔开度降低。hrb突变体的强气孔表型可能是由于红光和蓝光信号转导受损，因为红光通常增强蓝光响应。HRB 1基因已被分子克隆并编码一种核ZZ型锌指蛋白。HRB 1通过其ZZ型锌指结构域与磷酸酶7（或PP 7）（一种核丝氨酸/苏氨酸磷酸酶和蓝光信号的正调节剂）物理相互作用。本项目的目的是了解HRB在蓝光调节气孔开度中的作用。将研究HRB 1在向光素和隐花色素信号通路中的功能以及HRB 1在hrb 2和hrb 3背景中的功能。HRB 1和PP 7如何在体内和遗传上相互作用以及它们相互作用的性质也将被深入研究。更广泛的影响：本研究将为本科生、研究生和博士后提供极好的机会，以获得重要的研究经验，最重要的是，培养他们批判性地分析和解决科学问题的能力。包括非洲裔美国人和西班牙裔学生在内的一群不同的本科生过去在这个实验室进行了研究。13名本科生中有6名是来自全校生命科学暑期本科生研究项目的少数民族。学生在全国各地招募，在校园里度过10周，参加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，为本科生概述了一个具体的培训计划，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开辟新的可能性，并帮助植物在干旱中生存。气孔开度也受到其他环境因素的调节，如干旱和蓝光。鉴于hrb植物可能仍然响应阿坝，一个众所周知的干旱信号，这些植物应该享有的优势，组成和诱导的保护在水分限制条件下。

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.