Control of Phyllotaxy in Maize by ABPHYL1, a Cytokinin Inducibe Response Regulator Homolog

植物的形状或结构对农业产量有重大影响。建筑是形态发生的最终产物，在植物和动物中，形态发生始于胚胎发育的早期，发育出不同的器官和组织类型。植物的发育是通过一组称为分生组织的干细胞不断地启动器官来进行的。所有的嫩枝器官，如叶和花，都是由嫩枝分生组织以规则的方式启动的，称为叶序。几个世纪以来，这些模式是如何产生的一直是人们感兴趣的话题，数学家、物理学家和生物学家也一直感兴趣。器官以规则的方式启动可以优化光捕捉以进行高效的光合作用，并在一些植物中产生结构支持。在这个建议中，杰克逊博士将研究玉米的ABPHYL1(ABPH1)基因。ABPH1功能的丧失导致植物发育成相反和交叉的叶序，而不是玉米正常的交替或二列模式。ABPH1基因编码一种细胞分裂素诱导的反应调节同源基因，虽然这个基因家族已经知道几年了，但这是第一次报道这些基因中的一个失去功能表型。反应调节剂最早是在细菌中发现的，并在信号通路中发挥作用。因此，这些研究将探索植物中一个独特的发育问题和一个被预测为传递细胞分裂素信号的基因的新功能之间的联系。特别是，ABPH1蛋白和mRNA的表达将与其在叶分类中的作用相关，细胞分裂素对其表达的影响也将被记录在案。细胞分裂素可能调节叶序的假设也将通过在含有外源细胞分裂素的培养基上生长芽外植体或胚胎来检验。最后，微阵列分析将用于识别受ABPH1调控的基因，其中一些将通过基因分析来表征。这些研究应该有助于生物学的几个领域，包括发育调节、形态发生、信号和生长调节剂的活性。重要的是，它们应该促进激素生物学家和发育生物学家之间的互动。拟议中的研究也将引起其他学科的研究人员的兴趣，如数学和生物物理学。

Plant shape or architecture has a major impact on agricultural yields. Architecture is the end product of morphogenesis, which in plants, as in animals, commences during early embryogenesis with the development of distinct organ and tissue types. Plant development proceeds through the continuous initiation of organs from groups of stem cells called meristems. All of the shoot organs, such as leaves and flowers, are initiated from the shoot meristem in regular patterns known as phyllotaxies. How these patterns are generated has been a subject of interest for centuries, and has been of interest to mathematicians, physicists and biologists. Initiation of organs in regular patterns can optimize light capture for efficient photosynthesis, and in some plants generates architectural support.In this proposal Dr. Jackson will study the ABPHYL1 (ABPH1) gene of maize. Loss of ABPH1 function causes plants to develop with opposite and decussate phyllotaxy rather than the alternating or distichous pattern that is normal for maize. The ABPH1 gene encodes a cytokinin inducible response regulator homolog, and though this gene family has been known for several years this is the first report of a loss of function phenotype in one of these genes. Response regulators were first discovered in bacteria and function in signaling pathways. Therefore these studies will investigate the link between a unique developmental question and a novel function for a gene predicted to transduce cytokinin signals in plants. In particular, the expression of ABPH1 protein and mRNA will be described in relation to its role in phyllotaxy, and the effect of cytokinins on its expression will also be documented. The hypothesis that cytokinins may regulate phyllotaxy will also be tested, by growing shoot explants or embryos on medium containing exogenous cytokinin. Finally, microarray analysis will be used to identify genes that are regulated by ABPH1, and some of these will be characterized by genetic analysis. These studies should contribute to several areas of biology, including developmental regulation, morphogenesis, signaling and activity of growth regulators. Importantly, they should foster interactions between hormone biologists and developmental biologists. The proposed studies will also be of interest to researchers in other disciplines, such as mathematics and biophysics.