细胞质雄性不育水稻幼穗和花粉发育期的蛋白酶活性变化

CHANGES IN ACTIVITIES OF PROTEASES AT PANICLE AND POLLEN DEVELOPMENTAL STAGES OF CYTOPLASMIC MALE STERILE RICE

摘要:

水稻细胞质雄性不育系珍汕97A，在花粉母细胞形成期以后可溶性蛋白含量迅速降低。单核期仅为花粉母细胞形成期的56％，二核期和三核期分别为花粉母细胞形成期的36．4％和30．3％。保持系珍汕97B虽在花粉母细胞形成期后可溶性蛋白含量降低，但在二核期则有所增高，表现为鞍形变化过程。在花粉母细胞形成期后，珍汕97A的酪蛋白水解酶活性增高，单核期为前一时期的1倍，而珍汕97B的酶活性增幅较小。第一次枝梗分化期珍汕97A的内肽酶活性较珍汕97B高，而雌雄蕊形成期两者的酶活皆降低。整个发育期中珍汕97A的内肽酶活性较珍汕97B高15％至55．5％。珍汕97A在幼穗第一次枝梗分化期时氨肽酶活性较珍汕97B高。第二次枝梗分化期后，不育系和保持系的氨肽酶活性均下降。但花粉母细胞形成期后，珍汕97A的氨肽酶活性迅速增高，三核期达最高水平，这可能意味着此时大量蛋白质被水解。蛋白酶类抑制剂的实验表明，在雌雄蕊形成期后不育系和保持系含有半胱氨酸型氨肽酶和约10％含金属型氨肽酶；而在三核期，保持系的氨肽酶则主要为半胱氨酸型。不育系三核期含有的BAPA内肽酶包括半胱氨酸型、丝氨酸型，以及部分含金属酶类；而保持系三核期的内肽酶仅为丝氨酸型。不育系肽酶类型的变化，可能反映酶基因编码的去抑制。

Abstract:

The soluble protein content in spikelet of Zhenshan 97A of cytoplasmic male sterile rice decreased rapidly after the formation stage of pollen mother cell (PMC). It was 56%, 34.6% and 30.3% at uninucleate, binucleate and trinucleate stages of pollen, respectively, as compared with that at the formation stage of PMC. The content of soluble protein in maintainer line Zhenshan 97B also decreased, but again increased at pollen binucleate stage which showed a pattern with saddle curve The activity of azocasein protease increased in Zhenshan 97A after the PMC formation stage, whereas less change in activity of this enzyme was found in the maintainer line. The activity of endopeptidase in Zhenshan 97A at the stage of first panicle branch differentiation was higher than that in Zhenshan 97B, and it decreased at the stage of pistil and stamen formation in both the sterile and the maintainer lines. The activity of endopeptidase in sterile line was higher than that in maintainer line by 15% to 55.5% at all developmental stages. At the stage of first panicle branch differelltiation, tile activity of aminopeptidase for tile sterile line was higher than that for the maintainer one. After the stage of PMC formation, the activity of aminopeptidase increased rapidly and reached to the maximum level at pollen trinucleate stage for the sterile line. It may implay that more protein in sterile plants was proteolysised at this stage. The results of protease inhibitor test indicated that aminopeptidase in sterile and maintainer lines after the formation stage of pistil and stamen was of cysteine type with 10% of metalloprotease. However, aminopeptidase in maintainer line at trinucleate pollen stage belonged mainly to the cysteine type. Endopeptidase, BAPA, from sterile line at trinucleate stage showed cysteine- and serine types, and also part of type with metalloprotease, but it was the serine type only in maintainer line. The changes in peptidase types may reflect the derepression of the gene coding of peptidase in cytoplasmic male sterile rice.