固体基质引发西瓜种子的效果及其对β-半乳甘露聚糖酶活性和DNA复制的影响

Effect of Solid Matrix Priming for Watermelon Seed and Influence on Activity of Endo-β-Mannanase and DNA Replication

【目的】用固体基质引发(SMP)技术克服三倍体西瓜种子萌发障碍,有效提高种子发芽率40%,研究并发现引发机理。【方法】在SMP引发过程中西瓜种子的吸水速度缓慢并始终未达到饱和含水量,RNA积累速度和浓度高于对照。采用单粒种子凝胶扩散法和电泳法研究种子中β-半乳甘露聚糖酶的活性。【结果】SMP处理种子中的高酶活性种子的比率以及平均酶活性都高于未处理种子。流式细胞分析仪对引发种子DNA复制水平调查结果表明,SMP处理的种子在种子吸胀的各个阶段,胚根尖中6C与3C的比值都高于对照种子。用软-X射线对种子结构的检测发现,SMP处理过的种子胚乳套根尖处变薄。【结论】在SMP条件下西瓜种子中的生理、生化、DNA复制水平以及结构发生的变化与克服萌发障碍提高三倍体西瓜种子萌发能力相关。

[Objective] With solid matrix priming （SMP） technique, germination barriers oftriploid watermelon seeds were overcome and germination percentage was enhanced by 40%. [Method] The investigation of priming mechanism indicated that the water absorbing capacity was slower and not reached saturation of moisture content all the time and rate and the concentration of RNA accumulation increased during SMP process. Using single-seed gel-diffusion assay and electrophoresis method to measure the endo-β-mannanase activity in endosperm envelope of watermelon seeds during imbibition. [Result] The result showed that average activity of the endo-β-mannanase and the ratio of seeds with higher enzyme activity in primed seeds were higher than that in control seeds. Investigation of DNA replication levels in primed seeds with flow cytometric determination showed that the 6C：3C ratio in embryonic root tip cells was higher than the unprimed seeds at all stages of seed imbibition. Seed structure inspection with soff-x ray showed that the endosperm envelope of root tip area become thinner in SMP treated seeds. [ Conclusion] These results indicate that during and after SMP, the influence of seed physiology, DNA replication and seed structure in triploid watermelon seeds have a certain correlation with overcoming germination barriers and enhancement of germination capacity.