Interplay of auxin and jasmonates in tomato gynoecia development and fruit set

植物繁殖的成功依赖于花器官发育、受精和座果的紧密协调。植物激素生长素和茉莉酸(JA)在这些过程的时间和协调中起着重要的作用。我们的初步工作表明，生长素和茉莉酸在雌雄异株的发育和受精后座果的启动过程中相互作用。还鉴定了受生长素和茉莉酸共同调控的转录因子SlMYB21和SlMYB24。在项目的第一阶段，我们确定生长素反应因子SLARF8A和SLARF8B是雌雄异株发育和座果的中央调节因子。我们发现Slarf8a Slarf8b双突变体在花柱和柱头发育方面受到损害，并且不依赖受精而产生无核果实。此外，Slarf8a Slarf8b突变株的雌雄异株降低了JA水平以及SlMYB21和SlMYB24的表达。我们已经产生了含有SlMYb24和Slmyb21 Slmyb24双突变植株的突变体，并发现Slmyb24在雌蕊发育和座果方面显著增强了Slmyb21的表型。这些结果表明，SLARF8、SLMYB21/24和JA相互作用，调控花和果实的发育。在提案的更新中，我们旨在解决以下假设：(I)SlARF8促进JA的产生，可能是通过激活SlMYB21，而SlMYB21抑制SlARF8的表达；(Ii)SlMYB21和SlMYB24共同作用于调控花发育和座果的过渡；以及(Iii)SlARF8、SlMYB21/24和JA是柱头发育的中央调节因子。我们将通过研究SLARF8、SLMYB21/24和JA在雌蕊发育特别是柱头发育和座果过程中的遗传和分子相互作用来检验这些假说。我们将：1.通过双突变体和三突变体的产生和鉴定，阐明SlMYB21和SlARF之间的调控相互作用。2.鉴定SLMYB21和SLMYB24同时丧失功能的影响。3.研究野生型和突变型植物的柱头发育和基因表达。本研究有望对MYB和ARF在番茄生殖中的协同作用提供深入的认识，并将有助于阐明生长素和JA在番茄生殖调控中的相互作用。

Successful plant reproduction depends on tight coordination of flower-organ development, fertilization and fruit set. The plant hormones auxin and jasmonic acid (JA) play important roles in the timing and coordination of these processes. Our preliminary work suggested that auxin and JA interact in the regulation of gynoecia development and of the initiation of fruit set in response to fertilization. It also identified the transcription factors SlMYB21 and SlMYB24 as regulated by both auxin and JA. In the first period of the project, we identified the auxin-response factors SlARF8A and SlARF8B as central regulators of gynoecia development and fruit set. We found that Slarf8a Slarf8b double mutants are impaired in style and stigma development and produce seedless fruits independently of fertilization. Furthermore, gynoecia of Slarf8a Slarf8b mutant plants have reduced JA levels as well as SlMYB21 and SlMYB24 expression. We have generated mutants harboring a knockout of SlMYB24 and Slmyb21 Slmyb24 double mutant plants and found that Slmyb24 substantially enhances the Slmyb21 phenotype with respect to gynoecia development and fruit set. These results suggest that SlARF8, SlMYB21/24 and JA interact to regulate flower and fruit development. In the renewal of the proposal, we aim to address the following hypotheses: (i) SlARF8 promotes JA production, possibly by activating SlMYB21, and SlMYB21 inhibits SlARF8 expression; (ii) SlMYB21 and SlMYB24 act together to regulate flower development and the transition to fruit set; and (iii) SlARF8, SlMYB21/24 and JA are central regulators of stigma development. We will test these hypotheses by examining the genetic and molecular interactions among SlARF8, SlMYB21/24 and JA in gynoecia development and particularly stigma development, and in fruit set. We will: 1. Elucidate the regulatory interaction between SlMYB21 and SlARFs by generation and characterization of double and triple mutants. 2. Characterize the effect of simultaneous loss of function of both SlMYB21 and SlMYB24. 3. Characterize stigma development and gene expression in wild type and mutant plants. The research is expected to provide insights on the coordinated function of MYBs and ARFs in tomato reproduction and will shed light on the crosstalk between auxin and JA in the regulation of reproduction in tomato.