棉纤维发育相关酶活性的基因型差异与纤维比强度的关系

Fiber Strength and Enzyme Activities of Different Cotton Genotypes During Fiber Development

【目的】以纤维比强度差异较大的不同基因型棉花为材料,研究它们纤维发育过程中相关酶活性的动态变化与纤维比强度的关系,为探索改善棉纤维比强度的生理调控途径提供理论依据。【方法】选择棉纤维比强度分属高(科棉1号)、中(美棉33B)、低(德夏棉1号和苏棉15号)3种类型,4个不同基因型的品种,在大田栽培条件下,研究棉纤维次生壁加厚过程中相关酶活性的动态变化、纤维素累积和纤维比强度形成的关系。【结果】β-1,3-葡聚糖酶活性在次生壁加厚发育过程中呈下降趋势,蔗糖合成酶、过氧化物酶和IAA氧化酶活性变化均呈单峰曲线,基因型间差异主要表现在酶活性的大小和峰值出现的时间。科棉1号属高强纤维基因型,棉纤维中与纤维发育相关的酶活性在整个次生壁加厚期高于中、低强纤维基因型,前者酶活的动态变化与纤维素累积快速增长期的协调性好,纤维素累积平缓,纤维比强度增强的幅度大;反之,如低强纤维品种德夏棉1号和苏棉15号,其纤维发育相关酶在次生壁加厚期活性低,纤维素累积快速增长期短,纤维比强度增强的幅度小;美棉33B棉纤维发育相关酶活性、纤维素累积和纤维比强度形成特征介于上述两种基因型之间。【结论】不同基因型棉花纤维中与纤维发育相关的酶活性存在显著差异,该差异可能是导致纤维素累积特性及纤维比强度形成基因型间差异的主要生理原因之一。

[Objective] The study was conducted to investigate the genotypic differences in some enzyme activities during cotton fiber thickening, and to provide a theoretical basis for improving fiber strength physiologically. [Method] Field experiments were carried out in Nanjing, Jiangsu Province （cotton belts in lower basin of the Yangtze River） in 2004-2005 by using three genotypes with significantly different fiber strength. The study focused on the time course of sucrose synthetase, β-1, 3-glucanase, peroxidase and IAA oxidase activities during cotton fiber development. The sample bolls were collected from the first and second fruiting positions of six to eight sympodial branches. [Result] The results showed that β-1,3-glucanase activity continuously decreased during the secondary cell wall thickening in cotton fiber. The activity curves of other enzymes （sucrose synthetase, peroxidase and IAA oxidase） were all single peak curves and they might have had a certain synergistic effect during fiber thickening development. Meanwhile, there were obviously differences among three genotypes in the levels of enzyme activities and occurrence time of the curve peak. The cultivar （Kemian 1）, with high strength fiber, had higher peak value of the related enzyme （sucrose synthetase,β-1,3-glucanase, peroxidase and IAA oxidase） activities, and slower descent trends subsequently. These might have resulted in a longer and more tempered cellulose accumulation, and a wider range and longer period of fiber strength increasing. Cultivar （Dexiamian 1 or Sumian 15） with lower strength fibers acted the contrarily. And in the cultivar （NuCOTN 33B） with medium strength fiber, the items were intervenient. [Conclusion] There was a significant difference in enzyme activity among different genotypes, which may have led to the great difference in the characteristic of cellulose accumulation and the fiber strength formation in different cottons.