Extra-gynoecial pollen-tube growth in apocarpous angiosperms is phylogenetically widespread and probably adaptive.
Extra-gynoecial pollen-tube growth in apocarpous angiosperms is phylogenetically widespread and probably adaptive.
复制标题
DOI：
10.1111/j.1469-8137.2011.03912.x
复制
发表时间：
2012
期刊：
影响因子：
--
通讯作者：
Xiao-fan Wang;W. Armbruster;Shuang‐Quan Huang
中科院分区：
文献类型：
--
作者：
Xiao-fan Wang;W. Armbruster;Shuang‐Quan Huang
被子植物中花心皮的融合（合心皮）被认为允许合心皮物种的后代数量和质量比裸子植物和离心皮（无心皮）被子植物有显着的改善。鉴于离体心皮的缺点，为什么许多被子植物的离体心皮谱系如此成功，以及为什么有些谱系表现出离体心皮的逆转，仍然是一个进化上的难题。·为了研究合心结实的一些优势是否可以通过其他方式积累到离生果物种中，我们回顾了以前对离生果物种花粉管生长的研究，并记录了6个科中另外9个离生果物种的花粉管生长。·对散在的离心皮古双子叶植物、单子叶植物和真双子叶植物的解剖学研究表明，在经过花柱后，“额外”的花粉管离开完全受精的心皮，并生长到其他具有未受精胚珠的心皮。在许多物种中，这是通过单心皮的开口发生的，正如我们在这里报道的慈姑，慈姑，佛甲草和黄蕊花。·雌蕊群外的花粉管生长在离体结实的物种中普遍存在，这一发现排除了离体结实相对于合心结实的主要适合度成本的可能性，并可能有助于解释被子植物进化史中离体结实的持续性和多次逆转。
• 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.