土壤干旱对芭蕉芋根茎淀粉合成与品质的影响及生理分子机理

Canna edulis is an excellent high-starch crop planted in karst mountainous areas, southwest China, and it is also an important bioenergy species with great potentiality. However, the yield and starch quality have become to the bottleneck of edilbe canna industrial development. One of the major factors that limit the yield and quality is the water deficit in growth period, especially in the sub-taro development stage. Xingyu-2 is a cultivar of Canna edulis, with drought-resistance and higher yield. Observing the rhyzome development, studying starch systhesis and quality traits, filtering and cloning the gene related to starch systhesis and elucidating the relationship between gene expression and starch systhesis under drought stress condition can provide strong theoretical basis for the new cultivar population and the drought-resistant cultivation. The project will carry out the following research: First, study the anatomy and development of rhyzome under drought conditions. Second, develope physiological and biochemical study of starch systhesis. Third, clone genes related to starch systhesis and clarity the relationship between the starch systhesis and the gene expression under drought conditions. The project will not only provide strong theoretical support for the drought-resistance and high quality production of edible canna, but also provide theoretical guidance for breeding the drought-resistance and high quality cultivar of other high-starch crops.

高淀粉作物芭蕉芋是我国西南喀斯特山区优良的生物质能源作物，根茎产量和品质是芭蕉芋开发利用的限制瓶颈。喀斯特山区土层薄，持水能力差，生育期内尤其是子芋形成期水分缺乏是该区域芭蕉芋种植中的主要限制因素。'兴芋-2'是近年来培育的芭蕉芋抗旱高产品种，对'兴芋-2'根茎发育、淀粉合成与品质性状响应水分胁迫的机理进行深入研究，掌握干旱对其根茎发育、淀粉合成和品质形成的影响机理，筛选并克隆淀粉合成关键酶基因，从形态、生理和分子三个层次上阐明干旱对芭蕉芋根茎淀粉合成与品质形成的影响机制，可为芭蕉芋新品种的推广和抗逆栽培提高理论依据。本项目将从以下几个方面进行研究：1）干旱条件下的根茎发育学研究；2）干旱条件下的生理学研究；3）干旱条件下淀粉合成调控关键基因的克隆、表达及与淀粉合成的关系。项目的开展，不仅为芭蕉芋的抗旱优质栽培提供理论支撑，也为其他高淀粉作物的抗旱优质品种选育提供理论指导。

芭蕉芋是我国西南喀斯特山区优良的高淀粉生物质能源作物，喀斯特地区土层薄，持水能力差，生育期内尤其是子芋形成期水分缺乏是该区域芭蕉芋种植的主要限制因子。本项目以抗旱高产品种‘兴芋-2’为试材，以不抗旱品种‘兴芋-1’为对照，研究了干旱与芭蕉芋根茎产量及品质的关系，并从形态、生理和分子三个层次阐明了干旱对芭蕉芋根茎淀粉合成与品质形成的影响机制。研究发现干旱不仅降低根茎产量，改变成熟根茎中营养成分比例，尤其是降低淀粉、总蛋白及K含量；干旱还改变了淀粉热力学特征，降低了淀粉颗粒大小、糊化所需能量和膨胀度，改变了晶体结构，使淀粉易碎。干旱条件下，芭蕉芋叶片光合作用受到抑制，矿质吸收特别是N和K的吸收受阻，是造成芭蕉芋碳水化合物、矿质营养元素及蛋白降低的主要原因之一，另外，干旱改变了芭蕉芋干物质、碳水化合物及矿质营养元素元素的分配方向，使碳氮代谢物质优先向根和叶片分配，最大程度抵御干旱带来的伤害，是典型的耐旱性反应。干旱条件下，叶片和根茎中淀粉合成相关基因的表达也受到很大的影响，主要表现为干旱初期基因表达上调，但长时间的持续干旱淀粉合成酶基因下调，这是根茎淀粉降低的内在原因。