黄花草木樨选择性种子败育及其影响因素

Study on Selective Seed Abortion and Its Influencing Factors in Melilotus officinalis

黄花草木樨是一种广泛分布的豆科牧草,具6~7枚胚珠,但大多数荚果只形成1枚种子。对其种子形成过程、受精前后胚珠发育状况及相关因素进行分析,探究其种子败育原因及影响因素。结果显示:黄花草木樨种子发育从基部开始,从基部向上数3号位置以后的胚珠大量败育,最终1号位置80%的胚珠可形成种子;受精前,胚珠发育无明显的位置效应,胚珠结构在细胞学方面无异常;与资源运输相关的维管在受精前、后的分布也无明显的位置效应;花粉管在子房中的分布无明显位置效应;自然居群不存在花粉限制,自花粉和异花粉在柱头上均可萌发且能正常生长;在花芽期降低资源竞争可明显增加子房中的胚珠数,而在结荚期降低资源竞争不会改变荚果内的种子数及结籽格局。综上所述,黄花草木樨败育绝大多胚珠而保留个别种子的现象是一种由母本调控的种子选择性败育类型,可能是为了增加种子适合度或种子扩散强度的一种生殖对策。

Melilotus officinalis L.,a widely distributed leguminous forage grass with 6 to 7 ovules,but most pods form only one seed.In this experiment,the seed formation process,ovule development before and after fertilization and related factors were studied.The results showed that:The seed development of Melilotus officinalis started from the base of ovary,and most ovules were aborted after counting from the base to the third position,and finally 80%of the ovules in the first position could form seeds.Before fertilization,there was no obvious position effect in ovule development,and there was no cytological abnormality in ovule structure,there was no significant positional effect on the distribution of vascular associated with resource transportation before and after fertilization,there was no obvious position effect on the distribution of pollen tube in ovary.There was no pollen limit in natural population.Both Self-and cross-pollen could germinate on stigmas and grow normally.Reducing resource competition at the flower bud stage could significantly increase the ovule number in the ovary,but did not change the seed number and seed setting pattern in pod at the pod setting stage.In conclusion,the phenomenon that Melilotus officinalis retained individual seeds by aboring most ovules was a selective abortion type regulated by female parents,which may be a reproductive strategy to increase seed fitness or seed dispersal intensity.