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New Phytologist:汪小凡等被子植物心皮演化研究获进展

来源:武汉大学生命科学学院 2012-01-03 11:14

近日,植物学国际知名杂志New Phytologist在线刊登了生命科学学院汪小凡教授、黄双全教授等的最新研究成果“Extra-gynoecial pollen-tube growth in apocarpous angiosperms is phylogenetically widespread and probably adaptive。”文章中,两位教授在被子植物心皮的演化研究中取得了新的进展。

经典的观点认为从离生心皮演化到合生心皮是被子植物的一个重要变革。系统发育的分析表明虽然被子植物演化的主要趋势是从离生心皮到合生心皮,但仍存在着约1/4的逆向转变,即从合生心皮到离生心皮。为什么合生心皮要逆向演化为离生心皮?是被子植物演化中一个悬而未决的问题。汪小凡教授等曾在单子叶植物中首次发现花粉管可在离生心皮之间生长(Wang et al., 2002 Annals of Botany 89: 791-796),即在一个雌蕊中生长的花粉管可进入到其他的未授精的雌蕊中,释放精子使胚珠受精,从而提高了结实率。黄双全教授对发现这个不同寻常的花粉管生长方式的重要意义进行了评述(Huang, 2003 New Phytologist 158: 232-234)。他们进一步合作在多个离生心皮的植物类群中开展了调查研究,发现离生心皮类群中存在着较为普遍的心皮间花粉管生长。由于这些类群的离生心皮在功能上类似于合生心皮,能分享落置在不同雌蕊上的花粉,那么逆向演化就没有降低生殖成功的机会。

据悉这是黄双全教授课题组在New Phytologist《新植物学家》上发表的第7篇通讯作者论文。(生物谷Bioon.com)

Extra-gynoecial pollen-tube growth in apocarpous angiosperms is phylogenetically widespread and probably adaptiveExtra-gynoecial pollen-tube growth in apocarpous angiosperms is phylogenetically widespread and probably adaptive.

Xiao-Fan Wang1, W. Scott Armbruster2,3,4, Shuang-Quan Huang1

Keywords: Alismataceae;apocarpy;carpel anatomy;Crassulaceae;pollen-tube growth;Schisandraceae;syncarpy Summary Fusion of floral carpels (syncarpy) in angiosperms is thought to have allowed for significant improvements in offspring quantity and quality in syncarpous species over gymnosperms and apocarpous (free-carpelled) angiosperms. Given the disadvantages of apocarpy, it remains an evolutionary puzzle why many angiosperm lineages with free carpels (apocarpy) have been so successful and why some lineages show reversals to apocarpy. To investigate whether some advantages of syncarpy may accrue in other ways to apocarpous species, we reviewed previous studies of pollen-tube growth in apocarpous species and also documented pollen-tube growth in nine additional apocarpous species in six families. Anatomical studies of a scattering of apocarpous paleodicots, monocots, and eudicots show that, after transiting the style, ‘extra’ pollen tubes exit fully fertilized carpels and grow to other carpels with unfertilized ovules. In many species this occurs via openings in the simple carpels, as we report here for Sagittaria potamogetifolia, Sagittaria pygmaea, Sedum lineare, and Schisandra sphenanthera. The finding that extra-gynoecial pollen-tube growth is widespread in apocarpous species eliminates the possibility of a major fitness cost of apocarpy relative to syncarpy and may help to explain the persistence of, and multiple reversals to, apocarpy in the evolutionary history of angiosperms.

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