土壤通气性调控甘薯块根中光合产物卸载的生理机制

Good soil aeration is one of the key environmental factors to high storage root yield of sweet potato, whose product is storage root growing underground. Improving soil aeration increased dry matter distribution rate of storage root and storage root yield significantly by means of improving translocation and partitioning of photosynthate from source to sink of sweet potato mainly. However, the physiological mechanism of translocation and partitioning of photosynthate between sink and source induced by soil aeration was still lack and need further study. Therefore, we chose sweet potato varieties with different source-sink characteristics. Field experiment and pot experiment were combined and carried out to study the related indicators by microscopic observation and physiological and biochemical detection. The activities of enzymes, hormone content, gene expression and anatomical structure related to phloem unloading; activities of enzymes related to vacuolar compartmentalization, activities and gene expression of enzymes related to starch synthesis; the transition rate of photosynthate from source to sink were studied under different soil aeration to clarify the regulation mechanism of soil aeration on translocation and distribution of photosynthate between source and sink from phloem unloading and transformation of photosynthate. This study would fill the gaps in mechanism of promoting photosynthate transportation from source to sink, enrich and develop the culture theory for high-yielding of sweet potato.

甘薯以地下块根为产品器官，土壤疏松、通气良好是其获得高产的主要环境条件之一。改善土壤通气性主要通过促进源库间光合产物的运转与分配，提高块根中干物质分配率，显著增加块根产量。但是，土壤通气性调控甘薯源库间光合产物运转分配的生理机制，迄今认识较为薄弱。因此，本研究选用源库特性差异大的甘薯品种，采用田间试验与盆栽试验相结合、显微观察与生理生化检测相结合的方法，在不同土壤通气性条件下，研究块根中与光合产物韧皮部卸载相关的酶活、激素含量、基因表达量和韧皮部的解剖特性；液泡区隔化相关酶活性、淀粉合成相关酶活性和基因表达量；甘薯源库间光合产物的运转效率，从光合产物韧皮部卸载及卸载后的转化两个方面阐明土壤通气性对甘薯源库间光合产物运转与分配的调控机制及与产量形成的关系。研究结果可填补促进甘薯光合产物运转机制的认知不足，丰富和发展甘薯高产栽培理论。

项目背景：土壤通气性劣变是制约甘薯高产稳产的主要因素。改善土壤通气性可以促进光合产物由茎部向块根的卸载。但是，土壤通气性对块根中光合产物卸载的作用机制，迄今认识较为薄弱。.主要研究内容：（1）土壤通气性调控质外体空间蔗糖跨质膜进入块根细胞的作用机理；（2）土壤通气性调控卸载后蔗糖向淀粉转化的作用机理；（3）土壤通气性调控卸载后蔗糖向液泡区隔化的作用机理；（4）土壤通气性对源库间光合产物运转及块根膨大的调控机制。.重要结果和关键数据：改善土壤通气性能促进块根中光合产物的卸载，提高源端光合产物在块根中的分配率，促进块根膨大，形成较高的块根产量。改善土壤通气性主要通过三个方面促进块根中光合产物卸载：（1）是促进蔗糖跨质膜进入库细胞，主要通过提高不溶性酸性转化酶活性，促进质外体空间蔗糖的水解，增加筛管中蔗糖向质外体空间的释放量；提高蔗糖转运蛋白的表达量和质膜H+-ATPase活性，促进蔗糖的跨膜运转，同时，提高细胞质中蔗糖合酶（分解方向）的活性，促进卸载进入库细胞的蔗糖水解，保证胞质内外较高的蔗糖浓度梯度；（2）是促进卸载后蔗糖向淀粉转化，主要通过提高淀粉合成关键酶活性；（3）是促进卸载后蔗糖向液泡区隔化，主要通过提高可溶性酸性转化酶和液泡膜H+-ATPase活性。而淀粉合成关键酶活性的提高可能与ABA、ZR和BR含量的提高和GA含量的降低有关。.科学意义：本项目成果对于促进甘薯高产栽培理论发展、完善提高光合产物运转效率的技术途径，具有比较重要的理论意义和应用价值。