Sex-biased gene expression in flowers, but not leaves, reveals secondary sexual dimorphism in Populus balsamifera

First author: Brian J. Sanderson; Affiliations: Texas Tech University (德克萨斯理工大学): Lubbock, USA

Corresponding author: Matthew S. Olson

Because sexual dimorphism (雌雄二型) in plants is often less morphologically conspicuous (明显的) than in animals, studies of sex‐iased gene expression may provide a quantitative metric (度量) to better address their commonality (共性), molecular pathways, consistency (连贯) across tissues and taxa, and evolution. The presence of sex‐iased gene expression in tissues other than the androecium (雄蕊) or gynoecium (雌蕊), termed secondary sexual characters, suggests that these traits arose after the initial evolution of dioecy (雌雄异株). Patterns of sequence evolution may provide evidence of positive selection that drove sexual specialization (特化). We compared gene expression in male and female flowers and leaves of Populus balsamifera (香脂杨) to assess the extent of sex‐iased expression, and tested whether sex‐iased genes exhibit elevated rates of protein evolution. Sex‐iased expression was pervasive (普遍的) in floral tissue, but nearly absent in leaf tissue. Female‐iased genes in flowers were associated with photosynthesis, whereas male‐iased genes were associated with mitochondrial function. Sex‐iased genes did not exhibit elevated rates of protein evolution, contrary to results from other studies in animals and plants. Our results suggest that the ecological and physiological constraints associated with the energetics of flowering, rather than sexual conflict, have probably shaped the differences in male and female gene expression in P. balsamifera.

植物中雌雄二型相比于动物而言，在形态上差异要更小，对于植物性别偏好基因表达的研究可能有助于对不同组织、物种和演化过程中性别分化的共性、分子通路及连贯性有更好的了解。在雌雄蕊以外的其它组织，即次要性别特征中性别偏好基因表达说明了这些性状可能是在雌雄异株演化形成之后出现的。作者比较了香脂杨中雌雄花及叶片的基因表达以研究性别偏性表达的情况，并测试是否在性别偏性基因中存在更高的蛋白演化速率。结果显示在花组织中，性别偏性表达是普遍存在的，但在叶片组织中则几乎没有。雌花偏向的基因主要与光合作用相关，而雄花偏向性的基因主要与线粒体功能相关。研究还显示性别偏性基因的蛋白演化速率并未有所提升，这与其它动物和植物的研究有所差异。本文的研究说明了相比于性别冲突，与开花能量学相关的生态和生理限制更有可能导致了香脂杨中雌雄基因表达模式的差异。

通讯：Matt Olson (https://www.depts.ttu.edu/biology/people/faculty/olson/)

个人简介：德克萨斯大学奥斯丁分校，学士；路易斯安那州立大学，硕士；杜克大学，博士。

研究方向：杨树的区域适应性；植物细胞质雄性不育的演化。(p.s. 实验室网站：https://mattolson38.wixsite.com/olsonlab)

doi: https://doi.org/10.1111/nph.15421

Journal: New Phytologist

First Published: 04 September, 2018

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