Department of Botany, University of Jammu, Jammu 180 006, India.
J Biosci. 2009 Dec;34(6):977-90. doi: 10.1007/s12038-009-0112-5.
This paper describes the results of a series of experiments conducted to unravel the patterns of sex expression and reproductive output in a fascinating species with high variation in sexuality. Commelina benghalensis L., an andromonoecious rainy season weed, bears male and bisexual flowers in axillary spathes of all the plants investigated. Bisexual flowers are of two types; chasmogamous (CH) and cleistogamous (CL). The former are borne on subaerial and the latter on subterranean shoots, in addition to those on aerial spathes. Three populations of the species, designated JU1, JU2 and JU3, were scanned for three consecutive years from 1996 to 1998, and the number and distribution of male, CH and CL flowers per plant were found to vary. The mere number of CH/CL flowers per plant is by itself not an accurate measure of mixed mating. It is necessary to confirm that CH flowers actually outcross and, if they do so, to what extent. Comparison of the pollen/ovule (P/O) ratio and percentage pollen germination on the stigmas of the CH and CL flowers have been used as indices of the pollination system. Confirmation of this was sought from the fruit and seed sets obtained after manual pollination of emasculated flowers with self- and cross-pollen. Results so obtained were compared with those of natural pollination. In the majority of CH flowers, the male and female reproductive phases (i.e. anther dehiscence and stigma receptivity) overlap, providing for self-pollination. However, two exceptions to this general behaviour were found in some plants of all the three populations. In some CH flowers, the female phase matures prior to anther dehiscence while in others, the anthers are sterile. Such plants, designated as variants 1 and 2, respectively, facilitate cross-pollination. While the CL flowers contribute to the production of selfed progeny, the variants of CH ones permit formation of outcrossed progeny, indicating a mixed mating strategy in C. benghalensis.
本文描述了一系列实验的结果，这些实验旨在揭示一个具有高度性变异性的迷人物种的性别表达和生殖输出模式。孟加拉报春（Commelina benghalensis L.）是一种两性同株的雨季杂草，在所有调查的植物中，其腋生佛焰苞中都有雄性和两性花。两性花有两种类型；雌雄同熟花（CH）和闭花受精花（CL）。前者生于地上茎上，后者生于地下茎上，此外还有生于空中佛焰苞上的花。1996 年至 1998 年连续三年对该物种的三个种群（命名为 JU1、JU2 和 JU3）进行了扫描，发现每株植物的雄性花、CH 花和 CL 花的数量和分布都有所不同。仅仅是每株植物的 CH/CL 花的数量本身并不是混合交配的准确衡量标准。有必要确认 CH 花实际上是否异交，如果是，程度如何。比较 CH 和 CL 花的花粉/胚珠（P/O）比和柱头花粉萌发率被用作授粉系统的指标。通过对去雄花进行自交和异交授粉后获得的果实和种子数来确认这一点。将获得的结果与自然授粉的结果进行比较。在大多数 CH 花中，雄性和雌性生殖阶段（即花药开裂和柱头可接受性）重叠，提供了自交的机会。然而，在所有三个种群的一些植物中发现了两种例外情况。在一些 CH 花中，雌性阶段在花药开裂之前成熟，而在另一些花中，花药是不育的。这些植物分别被指定为变体 1 和 2，有利于异交。虽然 CL 花有助于产生自交后代，但 CH 花的变体允许形成异交后代，这表明孟加拉报春采用了混合交配策略。
