Safavian Darya, Jamshed Muhammad, Sankaranarayanan Subramanian, Indriolo Emily, Samuel Marcus A, Goring Daphne R
Department of Cell and Systems Biology, University of Toronto, Toronto, M5S 3B2, Canada.
Plant Reprod. 2014 Sep;27(3):121-7. doi: 10.1007/s00497-014-0245-z. Epub 2014 Jun 29.
We have previously proposed that Exo70A1 is required in the Brassicaceae stigma to control the early stages of pollen hydration and pollen tube penetration through the stigmatic surface, following compatible pollination. However, recent work has raised questions regarding Arabidopsis thaliana Exo70A1's expression in the stigma and its role in stigma receptivity to compatible pollen. Here, we verified the expression of Exo70A1 in stigmas from three Brassicaceae species and carefully re-examined Exo70A1's function in the stigmatic papillae. With previous studies showing that high relative humidity can rescue some pollination defects, essentially bypassing the control of pollen hydration by the Brassicaceae dry stigma, the effect of high humidity was investigated on pollinations with the Arabidopsis exo70A1-1 mutant. Pollinations under low relative humidity resulted in a complete failure of wild-type compatible pollen acceptance by the exo70A1-1 mutant stigma as we had previously seen. However, high relative humidity resulted in a partial rescue of the exo70A1-1 stigmatic papillar defect resulting is some wild-type compatible pollen acceptance and seed set. Thus, these results reaffirmed Exo70A1's proposed role in the stigma regulating compatible pollen hydration and pollen tube entry and demonstrate that high relative humidity can partially bypass these functions.
我们之前曾提出，十字花科植物柱头中需要Exo70A1来控制花粉水合作用的早期阶段以及在亲和授粉后花粉管穿透柱头表面的过程。然而，最近的研究对拟南芥Exo70A1在柱头中的表达及其在柱头对亲和花粉的接受能力方面的作用提出了疑问。在此，我们验证了Exo70A1在三种十字花科植物柱头中的表达，并仔细重新研究了Exo70A1在柱头乳突中的功能。此前的研究表明，高相对湿度可以挽救一些授粉缺陷，基本上绕过十字花科干燥柱头对花粉水合作用的控制，因此我们研究了高湿度对拟南芥exo70A1-1突变体授粉的影响。正如我们之前所观察到的，在低相对湿度下进行授粉时，exo70A1-1突变体柱头完全无法接受野生型亲和花粉。然而，高相对湿度导致exo70A1-1柱头乳突缺陷得到部分挽救，从而有一些野生型亲和花粉被接受并结籽。因此，这些结果再次证实了Exo70A1在柱头中调节亲和花粉水合作用和花粉管进入方面的作用，并表明高相对湿度可以部分绕过这些功能。
