Understanding the evolution of dimorphic flowers in maize through combined changes in transcriptional dynamics, hormone levels and genetic networks

通过转录动力学、激素水平和遗传网络的综合变化了解玉米二态花的进化

• 批准号: 1922543
• 负责人: Sarah Hake
• 金额: $ 37万
• 依托单位: University of California-Berkeley
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-08-15 至 2022-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1922543&HistoricalAwards=false
• 关键词: Understanding; evolution; dimorphic; flowers; maize

The biological rules that govern floral development are paramount, given that reproduction is critical to evolutionary success. Although most flowering plants produce only perfect flowers (those with both male and female structures), roughly 30% of species produce imperfect flowers, which have with either male (staminate) or female (carpellate) flowers. Imperfect flowers are associated with wind-pollination and increased outcrossing. Although other agriculturally domesticated plants in the grasses (ex. rice, wheat, millet, sorghum) produce perfect flowers, maize forms separate, staminate and carpellate inflorescences on the same plant. Separate male and female inflorescences have allowed plant breeding programs to generate elite, adapted maize varieties with highly productive female inflorescences and F1 hybrids. This research grant will employ multiple levels of organization to investigate floral characteristics in maize by 1) comparing the conservation of transcriptional dynamics during the development of staminate and carpellate inflorescences in maize with the perfect inflorescences of the closely related species, sorghum, 2) characterizing new floral mutants through analysis of hormone levels and molecular biology, 3) identifying candidate genes involved in the development of perfect and imperfect flowers by integrating developmental transcriptomics with hormone-responsive genetic pathways. Knowledge gained from the work will provide important insight into how reproductive structures are generated in cereal species through the coordinated activity of genes, hormones, and developmental evolutionary processes and will allow one to predict which genes can be used for manipulating floral dimorphism in other crops.Through analysis of maize mutants with altered male and female floral characteristics, it appears that at least three hormones, JA, GA, and BR, are necessary for specification of staminate and carpellate flowers in maize, often regulating pistil abortion in male flowers. In Aim 1, a transcriptional ontogeny of developing maize ears will be compared to the ontogeny of developing tassels and sorghum panicles. Unique male and female programs will be identified. In Aim 2, two new mutants, fun and Te2, will be analyzed. They are different than previously described inflorescence mutants and may provide new clues to the evolution of separate male and female inflorescences. The tassels of both have a more female architecture than the JA, BR or microRNA tasselseed mutants. They do not encode enzymes in hormone pathways or directly involve microRNAs. FUN is a nuclear localized protein of unknown function. TE2 is an ARF transcription factor. By identifying the interacting partners of FUN and the downstream targets of TE2, the network of inflorescence determination factors will be expanded. The goal of Aim 3 is to combine the approaches of Aims 1 and 2 alongside other public datasets to formulate rules of life that coordinate the evolution of imperfect flowers. Although research expects multiple evolutionary origins of imperfect flowers, known developmental mechanisms regulating organ abortion are limited and thus common specification genetic networks may be possible. With that in mind, the rules of rule that coordinate floral dimorphism in maize may apply to other grasses and angiosperms in general.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

考虑到繁殖是进化成功的关键，支配花卉发育的生物学规律是至关重要的。虽然大多数开花植物只开出完美的花（既有雄性结构又有雌性结构），但大约30%的物种会开出不完美的花，这些花要么有雄花（雄蕊），要么有雌花（无皮）。不完美的花与风媒传粉和增加的异交有关。虽然其他农业驯化的禾本科植物（如水稻、小麦、小米、高粱）能开出完美的花朵，但玉米在同一株植物上形成独立的、雄蕊化的和有心皮的花序。雌雄分开的花序使植物育种计划能够产生优秀的、适应性强的玉米品种，具有高产的雌性花序和F1杂交品种。本研究经费将从多个层面对玉米的花特性进行研究：1)比较玉米雄蕊花序和无皮花序发育过程中的转录动力学保护，以及与之密切相关的高粱的完美花序；2)通过激素水平和分子生物学分析鉴定新的花突变体；3)通过整合发育转录组学和激素响应遗传途径，鉴定参与完美花和不完美花发育的候选基因。从这项工作中获得的知识将为了解谷物物种如何通过基因、激素和发育进化过程的协调活动产生生殖结构提供重要的见解，并将允许人们预测哪些基因可以用于操纵其他作物的花二态性。通过对雌雄花性状改变的玉米突变体的分析，发现至少有三种激素JA、GA和BR对玉米雄蕊花和无皮花的形成是必需的，它们经常调节雄花的雌蕊败育。在目标1中，发育中的玉米穗的转录个体发生将与发育中的雄穗和高粱穗的个体发生进行比较。将确定独特的男性和女性程序。在Aim 2中，将分析两个新的突变体，fun和Te2。它们与先前描述的花序突变体不同，可能为分离的雌雄花序的进化提供新的线索。与JA、BR或microRNA突变体相比，这两种突变体的雄穗具有更多的雌性结构。它们不编码激素通路中的酶，也不直接涉及microrna。FUN是一种功能未知的核定位蛋白。TE2是一种ARF转录因子。通过确定FUN的相互作用伙伴和TE2的下游靶点，将扩大花序决定因子网络。目标3的目标是将目标1和目标2的方法与其他公共数据集结合起来，制定生命规则，协调不完美花朵的进化。尽管研究认为不完美花朵有多种进化起源，但已知的调节器官流产的发育机制是有限的，因此共同规范的遗传网络可能是可能的。考虑到这一点，协调玉米花二态性的规则可能普遍适用于其他禾本科植物和被子植物。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。