EVIDENCE OF A PRE-ANGIOSPERM ORIGIN OF ENDOSPERM - IMPLICATIONS FOR THE EVOLUTION OF FLOWERING PLANTS
EVIDENCE OF A PRE-ANGIOSPERM ORIGIN OF ENDOSPERM - IMPLICATIONS FOR THE EVOLUTION OF FLOWERING PLANTS
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DOI：
10.1126/science.255.5042.336
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发表时间：
1992-01-17
期刊：
影响因子：
56.9
通讯作者：
FRIEDMAN, WE
中科院分区：
文献类型：
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作者：
FRIEDMAN, WE
多倍体胚乳组织的形成一直被认为是被子植物独特的和决定性的特征（自形性）。与麻黄（一种与被子植物密切相关的非开花种子植物）的精核与卵核受精同时发生的，第二次受精事件先前已被证明发生在第二个精核和卵核的姐妹核之间。第二次受精产物的发育与原始开花植物胚乳的发育基本相似：两者的特征都是最初的核自由增殖期，随后是细胞化过程。然而，在麻黄中，第二次受精产物最终产生额外的胚胎。如果麻黄和被子植物的双受精在进化上是同源的，那么胚乳很可能是从最初产生胚的额外受精事件进化而来的，它产生了一个专门用于滋养合子胚的特殊的非胚组织。
The formation of a polyploid endosperm tissue has long been considered a unique and defining feature (autapomorphy) of angiosperms. Contemporaneous with the fertilization of an egg nucleus by a sperm nucleus in Ephedra trifurca (a nonflowering seed plant closely related to angiosperms), a second fertilization event has previously been shown to occur between a second sperm nucleus and the sister nucleus of the egg nucleus. Development of the second fertilization product is now shown to be fundamentally similar to that of endosperm in primitive flowering plants: both are characterized by an initial period of free nuclear proliferation followed by a process of cellularization. In Ephedra, however, the second fertilization product ultimately yields additional embryos. If double fertilization in Ephedra and angiosperms is evolutionarily homologous, it is likely that endosperm evolved from a supernumerary fertilization event that originally produced embryos into one that produced a specialized nonembryo tissue dedicated to the nourishment of the zygotic embryo.