基于人工异交授粉的源/库调节下星油藤产量形成的生理机制

More than 60% of the total demand of Chinese edible oil consumption relies on imports from abroad, among which are mainly from herbaceous oilseed crops. It has great significance to meet the needs of China's edible vegetable oil to find new woody oilseed plants with excellent features. Plukenetia volubilis, a promising woody oilseed plants indigenous to South America, was successfully introduced, and are developing in SW Yunnan China and north Loas, where 95% of the land is covered by mountains. Nowadays, P. volubilis plants were cultivated over 3,00 hectare. However, its yield varied greatly. Although the composition and properties of in seeds of P. volubilis plants are relatively well known, to date there is a lack of detailed information about cultivation potential. Thus it’s urgent to increase the seed oil yield in order to promote its industrial development.. P. volubilis plants don't experience winter dormancy and grow continuously in tropical regions, and therefore flower and fruit almost continuously throughout the year. However, the seasonal fruit (seed) abortion rate, especially in the early rainy season, during the reproductive stages is very high; and the artificial cross-pollination is very effective to improve the fruit set rate. Annual seed oil production of P. volubilis plants is mainly related to the total number of mature seeds per unit area and the seed size and oil content in different growth stages, but there is no detailed study on the yield formation and its underlying physiological mechanism.. In this proposal, we will select the P. volubilis plantation in Xishuangbanna Tropical Botanical Garden (alt. 560 m) as the studied site. First of all, based on our preliminary research, we intend to know the pollination biology with the reproductive characteristics of seasonal variation, and to elucidate the biological and physiological mechanisms of fruit abortion. In addition, we try to explore a scientific and efficient artificial pollination technique, which will be used to improve the fruit set rate of P. volubilis plants in the field.. Applying the artificial pollination technology during the different growth stage, we will regulate the source/sink of P. volubilis plants. Combined with the photosynthetic production, partition and yield elements (optimal fruit mature period, abortion rate, and seed size and oil content in different growth stages) of the individual plant level, we will track the physiological processes (carbon and nitrogen supply and conversion, hormone regulation) during the seed-filling stages in different seasons and years, in order to optimize the fruit mature time, and to unravel the physiological mechanism of yield formation (mainly focused on the seed abortion, duration of seed filling and seed-filling rate). Then, we will put forward the comprehensive regulation methods to improve the seed yield and quality of P. volubilis plants. The research findings of this project will reveal the seasonal and yearly dynamics of the formation of seed yield and quality and the underlying physiological mechanism of the maximum yield potential in the suitable planting area. If this proposal can be supported, the research results will provide the theoretical basis and technical support for the high-yield cultivation and industrial development of P. volubilis plants.

木本油料植物星油藤每个季节的败育率都较高，人工异交授粉是提高其座果率的前提。星油藤的周年种子油脂产量主要与单位面积成熟种子的总数量以及植株不同生长阶段种子的大小和含油率有关，但其产量的形成及其生理机制缺乏详细研究。结合前期研究基础，本项目拟从星油藤的传粉生物学特性入手，了解其生殖生物学特性的季节变化，阐明果实败育的生理机理，探讨科学、高效的人工授粉技术。在基于人工异交授粉技术下对不同生长阶段星油藤的源/库调节，结合植株个体水平的物质生产、分配和产量构成的主要要素（果实成熟的最优时期、败育率、不同生长阶段种子的大小和含油率），追踪不同季节和年份种子发育过程中籽粒充实的生理过程（碳氮的供应及转换、激素调节），以期优化果实成熟的时间，探讨其产量形成（籽粒败育和充实）的生理机制及其综合调控模式。本结果将揭示星油藤在适宜区域最大产量潜力的生理机制，为其山地种植推广和产业化提供理论依据和相关技术。

本项目研究结果表明：（1）星油藤很大程度上存在自交不亲和性。传粉限制和资源限制对于星油藤的种子形成都起着十分重要的作用，人工异交授粉可以大大提高其座果率。可溶性糖和氮是有效花形成相关和增加星油藤产量的起着十分重要的作用；种子总产量与植物组织的氮和非结构性碳水化合物库有密切正相关。2）碳，而不是氮，是星油藤植物的一个源驱动生长过程。源库调控改变了果实成熟的季节动态模式。种子总产量，取决于坐果和留果（即成熟果实的数量），而不是单个果实的发育（大小）；因减少库略有其产量，但减少源显著降低产量。去叶处理并没有富集KEGG途径，但下调了果实中TCA循环和糖脂代谢。减少源不仅不利于产量，而且不利于果实中碳水化合物和脂肪的积累。另外，一个生长季节内星油藤种子的总产量在很大程度上取决于植株的营养生长和繁殖生长之间的平衡。外源激素（特别是ABA和SA）可以提高星油藤种子产量和质量的有效途径。3）在星油藤-韭菜复合农林间作系统中，除了两种作物在空间上完全分离外，通过生态位分离获得地下资源的部分时间差异在整个生长季都发生。间作对健康单株细根性状、植株生长和种子产量的影响不大。间作显著抑制了爪哇根结线虫的种群数量，这与直接化感作用和本地微生物诱导抑制作用的综合效应有关。除真菌丰富度降低外，间作对微生物丰富度和α多样性没有影响。两种耕作制度下优势菌属的相对丰度存在显著差异。真菌属间作降低了镰刀菌和赤霉素的相对丰度，但增加了蜜环菌科、毛壳菌科、腐植酸和被孢霉的相对丰度。总体而言，复合间作系统抑制了爪哇根结线虫的种群数量，改变了微生物组成（特别是减少了含镰刀菌的病原菌），提高了产量和经济效益。4）局部环境过滤对藜麦土壤微生物群落的构建起着重要作用，但对根和叶内生真菌的作用较弱，根真菌除外。藜麦强抗非生物逆境的特性与其微生物群落相关。藜麦-星油藤较大规模的间作种植模式或许可行的，下一步需要进一步进行具体实验。