钙调素类似蛋白参与拟南芥花粉萌发和花粉管生长的实验证据
首发时间:2012-11-26
摘要:花粉是植物雄配子体的载体,其正常萌发和快速极性生长,对于开花植物成功受精并繁殖后代至关重要,因此,探讨花粉萌发和生长的调控网络,对于了解植物生殖调控机理和提高作物种子产量具有重要意义。胞内自由钙离子(Cytosolic Free Calcium)浓度变化是细胞重要的第二信使,参与了花粉萌发和生长的生理过程,但其生理调控机制并不清楚。我们发现一类钙调素类似蛋白(Calmodulin Like Protein,CML)参与了花粉萌发和花粉管生长,该蛋白编码基因PGCML1 (Pollen Germination and elongation related CML gene 1)在花粉和花粉管中高表达,其功能缺失突变体的花粉萌发率和花粉管长度均降低;且对胞外钾离子和钙离子的敏感性降低;进一步结果显示PGCML1在细胞质表达,并且其作用与一氧化氮及 钙离子信号转导途径相关。基于以上实验结果,我们推测,PGCML1可以通过调控一氧化氮及钙离子等胞内信号,影响跨膜离子转运,实现对花粉萌发及花粉管生长的调控。
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Functional characterization of an Arabidopsis Calmodulin-Like Protein PGCML1 in regulation of pollen germination and pollen tube growth
Abstract:The successful pollen germination and rapid tip elongation of germinated pollen tubes are essential for achievement of sexual reproduction of flowering plants, and the change of cytosolic free calcium concentration is a well known second messenger for the both processes. Consequently, the investigation of calcium-mediated signaling pathways in pollens and pollen tubes is indispensable for better understanding of male gametophyte signal transduction during double fertilization. Here, by using in-vitro and in-vivo pollen germination assayses, we found that an Calmodulin-Like-protein (CMLs), PGCML1 (Pollen Germination and elongation related CML1) is involved in pollen germination and pollen tube elongation. The germination rate and pollen tube length are dramatically reduced in pgcml1, a functional null mutant of PGCML1, and the sensitivity to exteranl potassium and calcium are also decreased; In addition, we found that PGCML1 is highly expressed mature pollens and pollen tubes with a cytosolic subcellular expression pattern and is involved in plant Nitric Oxide (NO) and calcium signaling. Base on our physiological and cellular observations, we hypothesize that PGCML1 may utilize NO and cytosolic calcium signaling to modulate transmembrane ion transportation, and thus regulate pollen germination and pollen tube elongation. It is the first time proved the involvement of the new caicium sensor candidate family in pollen signaling, and which opens a new gate to study the male gametophyte signal transduction during fertilization.
Keywords: Arabidopsis Calmodulin Like Protein Pollen Pollen Tube Calcium Signal
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