低磷影响棉花碳同化物代谢的生理机制研究

Phosphorus is one of the three essential macronutrients for cotton growth and development. Compared to nitrogen and potassium, the amount of phosphorus requirement is less, and it has an equal effect to cotton yield and quality. About 90% of carbohydrate from cotton yield is provided by the functional leaf. However, source capability of the functional leaf is not only relating to its photosynthesis ability but also relating to carbohydrate restore and recall ability. Therefore, under the background of available phosphate deficiency in soil and phosphate resource shortage, this research will focus its study on the carbohydrate transportation relating to the carbon assimilation metabolism and its difference in different genotype cultivars. The changes of the activities for the enzymes mediating carbon assimilation metabolism, the changes of the enzymes’ isoforms and the express characters of the genes encoding the enzymes and the relationship with phosphorus concentration in cotton will also be detailed analyzed. Thus, this research will elucidate the physiological mechanism of carbon assimilation metabolism in responding to low phosphorus stress, and the findings would be helped to develop effective techniques to alleviate low phosphorus and would be useful in low-phosphorus-tolerant cotton screening.

棉花在生长发育过程中需氮钾较多，需磷较少，但磷对其产量品质的影响与氮钾的相当。90%以上棉花产量所需的碳来自光合作用，但棉花的“源”能力不仅体现在光合能力，还应体现在功能叶对过剩光合产物的暂时储存能力和有效光合不足时对储存物质的再调动能力。因此，本研究在我国土壤有效磷缺乏及磷矿资源不足的背景下从棉花“光合产物运转—碳同化物代谢”的关系出发，以耐低磷能力差异显著的棉花品种为材料，通过低磷胁迫后棉花碳同化物代谢相关物质及其酶活性变化与植物磷浓度的相关关系，筛选对低磷胁迫响应敏感的关键物质与代谢关键酶，并分析其编码基因表达和同工酶谱变化，从“物质—酶活—蛋白—基因”4个水平系统揭示棉花碳同化物响应低磷及其耐低磷能力差异形成的生理与分子机制，为生产上探索低磷条件下提高棉花产量品质的生理调控途径和耐低磷型棉花品种选育提供理论依据。

以耐低磷型品种中棉所79和低磷敏感型品种鲁棉研28为试验材料，选择3个土壤有效磷处理——（3±0.5）mg kg-1 P2O5（重度低磷，P0）、（8±0.5）mg kg-1 P2O5（P1）和（12±0.5）mg kg-1 P2O5（P2），研究并阐明了不同基因型棉花碳同化物代谢响应低磷胁迫及其在不同基因型棉花中存在差异的生理机制，可为生产上探索低磷条件下提高棉花产量品质的生理调控途径和耐低磷型棉花品种选育提供理论依据。在本实验条件下，研究结果如下：.（1）土壤有效磷含量增加可促进棉花幼苗的磷吸收量和根系磷效率比，抑制磷的利用效率，但对磷转移效率无显著影响；低磷会降低棉花叶片中叶绿素含量、糖含量和氨基酸含量导致棉花生长受到抑制，适宜棉花幼苗生长发育的土壤有效磷的临界含量为9.0 mg·kg-1。.（2）低磷胁迫条件下，棉花铃数、铃重、籽棉产量、纤维长度、比强度和马克隆值显著降低，仅铃数、铃重、籽棉产量和纤维比强度在品种与磷处理间存在互作效应。.（3）鲁棉研28叶片中Rubisco和SPS活性对低磷的敏感性高于中棉所79。相关性分析表明，棉花叶片中较高的Pn、Rubisco活性和SPS活性有利于提高铃的生物量，但蔗糖积累对棉铃生物量的贡献不大。.（4）棉花中根系中蔗糖是响应低磷胁迫的关键物质。随土壤速效磷水平降低，棉花根系SPS、SuSy、碱性Inv活性呈下降趋势，而酸性Inv活性呈上升趋势，且鲁棉研28比中棉所79下降趋势更显著。.本项目培养硕士研究生2名，核心刊物发表论文4篇，其中SCI 3篇，另有1篇SCI外审，1-2篇论文待整理，较好地完成了既定目标。