峨眉拟单性木兰雄性不育的细胞形态学及生理生化特性研究

Cytomorphology, physiological and biochemical characteristics of male sterility plant in Parakmeria omeiensis

关键词:  峨眉拟单性木兰, 雄性不育, 花药发育, 生理生化特性, 形态学

Key words:  Parakmeria omeiensis, male sterility, anther development, physiological and biochemical characteristics, cytomorphology

摘要:

峨眉拟单性木兰(Parakmeria omeiensis)是木兰科(Magnoliaceae)拟单性木兰属(Parakmeria)的常绿乔木,属于国家Ⅰ级保护的极度濒危植物。为探究峨眉拟单性木兰两性花中雄性败育发生的时期及花药不同发育时期的生理生化特性,以两性花中的不育雄蕊和雄花中的可育雄蕊为材料,利用石蜡切片观察2种雄蕊的花药发育过程,并测定不同发育时期的可溶性糖、可溶性蛋白、脯氨酸的含量,分析过氧化氢酶(CAT)、过氧化物酶(POD)的活性。结果表明:(1)不育雄蕊与可育雄蕊在减速分裂时期出现明显差异,不育雄蕊的绒毡层致密、没有发育,四分体未形成,随后解体,花粉囊中无花粉; 可育雄蕊的绒毡层和小孢子母细胞发育正常,成熟时花粉囊开裂,花粉粒溢出。(2)不育雄蕊的可溶性糖含量、可溶性蛋白含量、脯氨酸含量,在减数分裂时期、单核期和花粉成熟期都显著低于可育雄蕊。(3)不育雄蕊POD活性整体呈上升趋势,在减数分裂时期、单核期和花粉成熟期都显著高于可育雄蕊; 不育雄蕊CAT活性整体呈下降趋势,显著低于同时期的可育雄蕊。综上认为,两性花中雄性败育发生在减速分裂时期,其败育的主要原因是物质能量代谢降低,绒毡层没有进一步发育,不能给小孢子母细胞提供营养物质; 过氧化氢酶及过氧化物酶的活性异常,造成细胞内不能及时清除自由基,使小孢子母细胞的减数分裂受阻,无法形成四分体。该研究结果为深入开展峨眉拟单性木兰雄性不育的分子机制、性系统演化机制研究奠定了基础。

Abstract:

Parakmeria omeiensis an evergreen tree belonged to Parakmeria of Magnoliaceae, is listed as a critically endangered plant under the first-grade State protection. Aimed to clarify the abortion period of male sterility in bisexual flowers of P. omeiensis and its physiological and biochemical characteristics, sterile stamens of bisexual flower and fertile stamens of male flower were test materials, the anther development was observed by paraffin section, the contents of soluble sugar, soluble protein, proline were determined, and catalase(CAT)and peroxidase(POD)activities were analyzed. The results were as follows:(1)Significant difference were detected in meiosis stage in anther development between sterile stamens and fertile stamens, the tapetum layer of sterile stamens was dense and undeveloped, the microspore mother cells didn't develop into the tetrad and subsequently disintegrated, so the pollen sac was empty. The tapetum layer and the microspore mother cells of fertile stamens developed normally, most pollen sac were broken and pollen grain were export.(2)The contents of soluble sugar, soluble protein, proline of sterile stamens were significantly lower than fertile stamens during the stages of meiosis, microspore monuclear and pollen mature.(3)POD activity of sterile stamens increased overall and was significantly higher than fertile stamens during the stages of meiosis, microspore monuclear and pollen mature. CAT activity of sterile stamens decreased as a whole and was significantly lower than fertile stamens in the same stage. We conclude that the microspore abortion occurs at the stage of meiosis, the decrease in metabolism of material and energy causes the abortion of male in bisexual flowers, the tapetum layer don't develop further and it doesn't provide nutrients to the microspore mother cells. CAT and POD activities are abnormal which results in the failure of timely scavenging free radicals in cells, and meiosis of microspore mother cells is blocked, so tetrads fail to be formed.