雪松花粉的淀粉粒在萌发过程中的变化

Changes in starch granules in Cedrus deodara pollen during germination

关键词:  风媒花粉, 雪松花粉, 淀粉粒, 花粉萌发, 淀粉酶活性, 淀粉结合蛋白

Key words:  anemophilous pollen, cedar(Cedrus deodara)pollen, starch granules, pollen germination, amylase activity, starch-associated proteins

摘要:

裸子植物雪松(Cedrus deodara)为风媒传粉植物,其花粉萌发和花粉管生长速率明显比被子植物(如玉米)慢。淀粉是风媒植物花粉萌发的主要能量来源。为揭示雪松花粉淀粉粒的特征及其在花粉萌发过程中的变化,该研究以雪松和玉米的花粉为材料,通过生理生化、细胞学和蛋白质组学手段比较花粉萌发过程中淀粉粒的变化及其对花粉管生长的影响。结果表明:(1)与玉米成熟花粉相比,雪松花粉中的淀粉含量较低,但直链淀粉比例较高。(2)雪松花粉的淀粉粒呈不规则鹅卵石状,而玉米花粉的淀粉粒为短棒状。(3)雪松花粉中的α-淀粉酶和β-淀粉酶的活性、同工酶种类和酶活性均低于玉米花粉。(4)雪松成熟花粉中的淀粉粒主要分布在花粉壁内侧的细胞质中,在花粉萌发过程中逐渐进入花粉管; 同时,淀粉同工酶种类和酶活性增加,淀粉降解加强,可溶性糖含量增加,从而为花粉萌发提供能量。该研究为阐明裸子植物风媒花粉萌发和花粉管生长较慢的原因提供了新线索。

Abstract:

The gymnosperm cedar(Cedrus deodara)is a wind-pollinated plant, and exhibits a significantly slower process of pollen germination and pollen tube growth than that of angiosperm(e.g., maize). Starch is the main energy source for pollen germination in wind-pollinated plants. To reveal the characteristics of starch granules in cedar pollen and their changes during pollen germination, the pollens of cedar and maize were used as materials to compare the changes of starch granules and their effects during pollen germination by physiological and biochemical, cytological and proteomic approaches. The results were as follows:(1)Compared with mature maize pollen, the starch content in cedar pollen was lower, but the amylose proportion was higher.(2)Starch granules in cedar pollen were irregular and cobblestone-like, whereas those in maize were short and rod-shaped.(3)The activities of α-amylase and β-amylase, and the types and activities of isoenzymes were much lower than those in maize pollen.(4)Starch granules in mature cedar pollen were primarily distributed in the cytoplasm around the inner pollen wall, and gradually moved into pollen tube during pollen germination. Meanwhile, the types and activities of starch isoenzymes increased, and the degradation of starch increased, thereby producing more soluble sugar to provide energy for pollen germination. This research provides new clues for understanding the reasons for the slow pollen germination and pollen tube growth of gymnosperms.