Identification and Characterization of Transcription Factors Regulating Carotenoid Pigmentation During Mimulus Flower Development

类胡萝卜素是黄色、橙色和红色的色素，有助于许多花（如水仙花、黄花菜、向日葵）和水果（如橙子、西红柿、芒果）的美丽颜色和营养价值。它们作为视觉色素，在植物的生态学和进化中起着吸引动物授粉和传播种子的重要作用。在花和水果中发现的类胡萝卜素色素沉着模式的巨大多样性主要是由控制类胡萝卜素色素何时何地产生的调节基因决定的。然而，人们对这些调控基因的身份和功能知之甚少。本研究利用猴花这一新的植物遗传模式系统，对类胡萝卜素调控基因进行了鉴定和功能表征。这些调控基因的发现和特征对于理解花发育过程中类胡萝卜素的产生是如何被控制的，以及在进化过程中基于类胡萝卜素的花色变化是如何产生的至关重要。从实际的角度来看，由于类胡萝卜素也是人类饮食的重要组成部分，是维生素a生物合成的前体，因此本研究中发现的调控基因在植物育种中具有很高的转化影响，可以提高作物植物中类胡萝卜素的产量。这些植物材料将被纳入康涅狄格大学的一个活体植物展览中，向学生和公众教育展示遗传学和进化的概念。此外，该项目产生的花卉图像、授粉视频和交互式多媒体插图将被开发成一个新的植物生物学部分，在国内和国际公认的学习。遗传学网站作为在线教育资源。本研究利用最近开发的基因组资源、稳定的转基因工具和猴花（Mimulus）的化学诱导突变体来鉴定和表征调节花类胡萝卜素色素沉着的转录因子。PIs实验室的初步研究结果支持了中心假设的形成：一个转录调控复合体，包含至少一个R2R3-MYB和一个四肽重复（TPR）蛋白，在拟南芥花发育过程中直接激活类胡萝卜素生物合成基因，调控基因的差异表达有助于物种间色素模式的变化。在这个拟议的项目中，转录调控复合物的其他成分将通过对另一个非等位基因突变体的大量分离分析和使用MYB和TPR蛋白作为诱饵的酵母双杂交筛选来鉴定。MYB和TPR基因调控类胡萝卜素色素沉着的功能机制将通过蛋白质-蛋白质和蛋白质- dna相互作用测定来确定。这些调控基因在产生花色变异中的作用将通过基因表达分析和转基因实验在具有不同类胡萝卜素色素沉着模式的拟南芥中进行检验。

Carotenoids are yellow, orange, and red pigments that contribute to the beautiful colors and nutritive value of many flowers (e.g., daffodils, daylilies, sunflowers) and fruits (e.g., oranges, tomatoes, mangos). They serve an important function in the ecology and evolution of plants as visual pigments to attract animals for pollination and seed dispersal. The tremendous diversity of carotenoid pigmentation patterns found in flowers and fruits is primarily determined by regulatory genes that control when and where the carotenoid pigments are produced. However, little is known about the identity and function of these regulatory genes. This study employs a new plant genetic model system, monkeyflowers, to identify carotenoid-regulating genes and to characterize their function. The discovery and characterization of these regulatory genes are crucial to understanding how carotenoid production is controlled during flower development and how carotenoid-based flower color variation is generated during evolution. From a practical perspective, because carotenoids are also essential components of human diets as precursors for vitamin A biosynthesis, the regulatory genes discovered in this study have the potential for high translational impact in plant breeding to enhance carotenoid production in crop plants. The plant materials will be incorporated into a live plant exhibit at the University of Connecticut to demonstrate concepts of genetics and evolution for student and public education. Furthermore, the flower images, pollination videos, and interactive, multimedia illustrations resulting from this project will be developed into a new Plant Biology section on the nationally and internationally recognized Learn.Genetics website as online educational resources. This study leverages recently developed genomic resources, stable transgenic tools, and chemically induced mutants of monkeyflowers (Mimulus) to identify and characterize transcription factors that regulate flower carotenoid pigmentation. Results from preliminary work in the PIs laboratory allows the formulation of the central hypothesis: a transcriptional regulatory complex, containing at least an R2R3-MYB and a tetratricopeptide repeat (TPR) protein, directly activates carotenoid biosynthetic genes during flower development in Mimulus, and differential expression of the regulatory genes contributes to pigment pattern variation between species. In this proposed project, additional components of the transcriptional regulatory complex will be identified by bulk segregant analysis of another non-allelic mutant and by yeast two-hybrid screening using the MYB and TPR proteins as baits. The functional mechanisms of the MYB and TPR genes in the regulation of carotenoid pigmentation will be determined by protein-protein and protein-DNA interaction assays. The role of these regulatory genes in producing flower color variation will be examined by gene expression analysis and transgenic experiments in Mimulus species that display distinct carotenoid pigmentation patterns.