云南高原寒地粳稻氮素同化与碳代谢对低温胁迫的响应机制

Chilling damage and low efficiency of nitrogen utilization has been a important factor resulting in severe yield loss and quality, such as Yunnan Provence. We have developed the cold-tolerant near-isogenic lines (BC4F8) was developed by backcrossing between ‘Lijiangxintuanheigu’ (cold-stongly tolerant landrace) as a donor parent and ‘Towada’ (cold-sensitive cultivar) as a recurrent parent, which six NILs with different nitrogen uptake and utilization were used as test material. The objective of this study was to determine the effects of interaction between cold low temperature stress and N application levels on the root morphological and physiological characters, endogenous hormone balance, distribution of root-shoot matter, the senescence physiological progress of root and leaf. To explore the root population characteristics and physiological index regulating N absorption function of rice root. In order to reveal physiological and molecular regulation of nitrogen assimilation by cold stress and N, through the key enzymes activities (NR、GS、GOGAT、GDH) in nitrogen metabolism, the expression responses of key enzymes genes and protein in leaves; amino acids component, nitrogen content and protein in leaves and grain were investiaged. The photosynthetic physiology and carbon metabolizing enzymes (RuBP、SPS、SS、SSS) activities were analyzed, and clarify the relationship between grain yield, quality formation and photosynthetic performance, carbon and nitrogen metabolism balance. The result of project will further clarify cold mechanisms of nitrogen regulation, and provide a new idea and theoretical basis for the breeding of high yield and N efficiency cultivars, adverse resistance cultivation and efficient production regulation in the cold region japonica rice.

低温与氮素利用率低是制约云南高原寒地粳稻产量和品质提高的重要因素。本项目拟以供体亲本云南地方强耐冷稻种丽江新团黑谷和轮回亲本冷敏感品种十和田构建的孕穗期耐冷近等基因系(BC4F8)群体中筛选的耐冷、氮素利用差异较大的6份NILs为材料，设置低温胁迫、供氮水平处理，研究低温和氮耦合对水稻根系形态和生理、激素平衡及根-冠物质分配和根叶衰老特性的影响，探明调控根系氮吸收功能关键根系群体特征及生理指标；分析叶片和籽粒氨基酸组分、氮素和蛋白质含量，研究氮素同化关键酶（NR、GS、GOGAT、GDH）活性、调控基因和差异蛋白表达，揭示低温和氮互作下氮同化的生理与分子调控机制；分析光合生理和碳代谢关键酶（RuBP、SPS、SS、SSS）活性，揭示寒地粳稻产量、品质形成与光合性能、氮碳代谢平衡的关系，为丰富氮调控水稻耐冷机理，以及水稻耐冷和氮高效品种选育、抗逆栽培、提质增效提供新思路和理论依据。

低温与氮素利用率低是限制寒地粳稻增产、增效的因子。本项目以云南强耐冷氮高效丽江新团黑谷（供体）和冷敏氮低效十和田（受体）构建的NILs I16（耐冷氮高效）、I67（冷敏氮低效）为材料，设置低温与氮耦合处理，研究云南高原寒地粳稻氮素同化与碳代谢对低温胁迫的响应机制。结果表明：（1）水稻细分枝根、粗分枝根和不定根较长，根表面积、体积、根系总吸收面积和活跃吸收面积大，根系氧化、还原力强，维持根叶中较高的IAA、CTK、GA含量及CTK/IAA、GA/ABA、CTK/ABA平衡，CAT、POD、SOD活性，以及叶片丝氨酸、谷氨酸、甘氨酸、缬氨酸含量高，MDA低，是寒地粳稻氮素高效吸收和同化的基础。（2）耐冷氮高效材料氮素转运、再利用率高，中氮促进水稻氮素同化酶（NR、GS、GOGAT、GDH）活性。低温与低氮耦合诱导水稻根部硝酸盐转运蛋白NRT1.1a、NTT1.1b、NRT2.1，以及氮素同化基因OsGS1.1、OsNR1、OsNADH-GOGAT过表达增强耐冷性及氮同化。DIA分析揭示差异表达蛋白osa0315、osa00940、osa00230、osa00190、osa03060调控耐冷、氮代谢的信号通路。（3）低温和低氮显著降低光合参数（SPAD、叶绿素、Rubisco酶、Pn、Tr、Ci、Fv/Fm）及碳代谢酶（SS、SSS、SPS、GBSS）活性。中氮增强碳代谢，高氮则抑制。在温暖粳稻区、籼粳交错区，减少氮高效材料开花期、灌浆期施氮量可提高光合性能。（4）低温降低水稻产量、氮素收获指数、氮素稻谷生产效率和氮肥吸收利用率。寒冷粳稻区、冷凉粳稻区施氮过高，导致水稻成熟期部分氮素滞留在茎鞘、稻草中，氮素“奢侈”吸收。（5）低温降低稻米整精米率、胶稠度、直链淀粉和蛋白质，垩白粒率、垩白度、碱消值增加。糙米率、整精米率、垩白粒率、垩白度、碱消值、蛋白质随施氮量增加而升高，胶稠度、直链淀粉相反。本项目成果为水稻耐冷氮高效品种选育、抗逆栽培、提质增效提供理论依据。