SEED ABORTION IN WIND-DISPERSED PODS OF DALBERGIA-SISSOO - MATERNAL REGULATION OR SIBLING RIVALRY
SEED ABORTION IN WIND-DISPERSED PODS OF DALBERGIA-SISSOO - MATERNAL REGULATION OR SIBLING RIVALRY
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DOI：
10.1007/bf00380936
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发表时间：
1988-01-01
期刊：
影响因子：
2.7
通讯作者：
SHAANKER, RU
中科院分区：
文献类型：
--
作者：
GANESHAIAH, KN;SHAANKER, RU
黄檀（Dalbergia sissoo）是一种被风吹散的热带树木，每荚的种子分布呈正偏态。这是由于较少种子的豆荚由于其减少翼载荷（重量与豆荚表面积的比率）和较低的沉降速度而增强了传播优势。研究了引起正偏态分布的近似机制。这种分布可能与单子房胚珠数分布模式、花粉粒数限制、胚珠不受精或受精后多粒荚果的消失无关。相反，它是由受精后2周内荚果内种子的受精后流产引起的。这种荚果内种子败育（IPSA）是由于受精的时间差异造成的受精胚珠从远端（柱头附近）到基端存在优势等级。在远端的优势发育种子通过流产剂的产生和扩散引起其它种子的流产。当兄弟姐妹的优势等级不强烈时，豆荚由多个种子组成。我们认为，每荚种子的正偏斜分布不是由于母亲的调节，而是兄弟姐妹竞争的结果。我们提出这种兄弟竞争是由花粉粒适合度的遗传差异产生的，并在亲子冲突的背景下讨论了结果。
Dalbergia sissoo, a wind-dispersed tropical tree, shows a positively skewed distribution of seeds per pod. This is attributed to the enhanced dispersal advantage of few-seeded pods due to their reduced wing loading (ratio of weight to pod surface area) and low setting velocity. The proximate mechanisms causing the positively skewed distribution were investigated. The distribution could not be attributed to the distribution pattern of ovule number per ovary, pollen grain limitation, lack of ovule fertilization, or post-fertilization elimination of many-seeded pods. Rather, it was caused by the post-fertilization abortion of seeds within a pod 2 weeks after fertilization. This intra-pod seed abortion (IPSA) is due to a dominance hierarchy of fertilized ovules from the distal (near stigma) to the basal end, generated by the temporal differences in fertilization. The dominant developing seeds at the distal end cause the abortion of others through the production and diffusion of an aborting agent. When the dominance hierarchy of the siblings is not intense, pods are formed with more than one seed. We argue that the positively skewed distribution of seeds per pod is not due to maternal regulation but is a result of sibling rivalry. We propose that this sibling rivalry is generated by genetic differences in pollen grain fitness and discuss the results in the context of parent-offspring conflict.