狗枣猕猴桃伴花彩叶光合功能适应其结构变化的机制研究

Actinidia kolomikta (Maxim. ＆ Rupr.) Maxim. is an important fruit tree resources in China. There exist a large number of variegated leaves during florescence, which is one of the important biological characteristics. For most fruit trees of leaf expansion first and then flowering, leaf photosynthetic function is very important to flowering and fruit setting. Our previous study showed that the photosynthetic capacity of variegated leaves at mature stage is only slightly lower compared with normal green leaves. However, there exits significant differences in anatomy between variegated and normal green leaves. Therefore, these results seem to suggest that photosynthesis acclimation to the anatomy of variegated leaf are helpful in maintaining photosynthetic function, which may provide energy and material for flowering of A. kolomikta. To test this hypothesis, the influences of photosynthesis on flowering process will be studied, thus to reveal the important role of photosynthetic function maintenance of variegated leaves for flowering. Second, anatomy and transcriptome of variegated leaves will be analyzed to elucidate the mechanisms underlying anatomical changes at late development stage. On this basis, the relationship between chlorophyll distribution in different mesophyll layer and anatomical changes will be studied to clarify the effects of anatomy changes on light utilization within leaf. And then, the influences of anatomical changes on carbon assimilation, key enzyme and gene expression of different mesophyll layer within leaf will be explored to discover the regulation of carbon assimilation and related mechanisms. This project will reveal the key acclimative mechanisms of photosynthetic function to anatomical changes during florescence in variegated leaves, which will provide theoretical basis for improving flowering regulation and increasing fruit setting.

狗枣猕猴桃是我国重要果树资源，花期伴生大量彩叶是其重要生物学特征之一。就先叶后花的果树而言，叶片光合功能对开花及坐果至关重要。前期研究表明，狗枣猕猴桃成熟彩叶与绿叶相比光合能力差异较小，但叶片结构差异非常明显。因此，推测彩叶光合作用能够通过适应其结构变化维持较高的光合功能，从而为狗枣猕猴桃开花提供物质和能量。为证明上述假设，本项目首先研究彩叶光合作用对开花的影响，证明其光合功能对开花的重要性。其次，探讨彩叶发育后期的结构变化，阐述其主要结构特征及形成机制。在此基础上，研究彩叶各细胞层叶绿素含量和空间分布的差异，阐明结构变化对光能吸收、利用策略的影响。进而，探讨彩叶不同细胞层碳同化产物、关键酶及相关基因表达与结构变化的关系，阐明碳同化适应结构变化的规律及机制。本项目将揭示狗枣猕猴桃伴花彩叶光合功能适应结构变化的关键机制，丰富光合作用研究，为花期调控、提高坐果率等相关栽培技术改进提供理论依据。

狗枣猕猴桃是我国重要果树资源，花期伴生大量彩叶是其重要生物学特征之一。就先叶后花的果树而言，叶片光合功能对开花及坐果至关重要。研究表明，生殖枝上，白叶与花直接环割后，花不能正常发育。白叶栅栏和海绵组织厚度均显著高于绿叶，但白叶栅栏组织细胞中叶绿体发育不完善，而其海绵组织中叶绿体发育完好。白叶叶绿素含量虽然显著低于绿色叶片，但白叶叶绿素主要分布在海绵组织。自然光照下，白叶光合速率最高可以达到绿色叶片的82%左右，白叶栅栏组织光化学效率和量子产率显著低于绿色叶片，但白叶海绵组织光化学效率和量子产率显著高于绿色叶片，涉及光合作用的一些关键基因在白叶中上调说明这些基因可能参与调节白叶糖合成和光合能力的维持。本研究揭示狗枣猕猴桃伴花彩叶光合功能适应结构变化的关键机制，丰富光合作用研究，为花期调控、提高坐果率等相关栽培技术改进提供理论依据。