盐胁迫下桑树叶片D1蛋白周转和叶黄素循环对PSⅡ的影响  

Role of D1 Protein Turnover and Xanthophylls Cycle in Protecting of Photosystem Ⅱ Functions in Leaves of Morus alba under NaCl Stress

作　　者：张会慧[1] 张秀丽[1] 李鑫[1] 许楠[1] 孙广玉[1] 

机构地区：[1]东北林业大学生命科学学院,哈尔滨150040

出　　处：《林业科学》2013年第1期99-106,共8页Scientia Silvae Sinicae

基　　金：国家自然科学基金项目(30771746;31070307);黑龙江省自然科学基金重点项目(ZD201105);国家科技支撑项目(2011BAD08B02-3);黑龙江重大项目(GA09B201-02);国家林业局科技推广项目(2010-29号;2011-32号)

摘　　要：采用抑制剂法研究盐胁迫下D1蛋白周转和叶黄素循环对桑树叶片PSⅡ功能的影响。结果表明:桑树叶片在100mmol·L-1NaCl胁迫下保持较高的PSⅡ反应中心的活性,具有完善的光破坏防御机制。通过硫酸链霉素(SM)抑制D1蛋白的周转和二硫苏糖醇(DTT)抑制叶黄素循环,损伤盐胁迫下桑树叶片的PSⅡ反应中心,加剧盐胁迫对桑树叶片PSⅡ反应中心的伤害,说明D1蛋白周转和叶黄素循环在保护盐胁迫下桑树叶片PSⅡ功能中发挥重要的作用,并且D1蛋白周转的保护作用大于叶黄素循环。DTT抑制盐胁迫下桑树叶片的叶黄素循环,却将PSⅡ反应中心吸收的光能大部分以无效的荧光和热能形式耗散,减缓过剩激发能对PSⅡ反应中心的伤害程度。SM处理可抑制D1蛋白周转,减弱盐胁迫下桑树叶片以叶黄素循环为主的耗散非辐射能量的能力,降低过剩激发能的热耗散程度,导致叶片中的过剩光能(1-qP)/NPQ成倍积累,造成PSⅡ反应中心大量失活。因此,SM不但可抑制D1蛋白的周转,还可增强QB的还原程度,降低电子传递链上的电子传递,PQ库容量降低,减弱依赖PQ在类囊体膜两侧建立质子梯度(△pH)的能力,从而限制依赖于△pH的叶黄素循环。因此,盐胁迫下抑制D1蛋白的周转不但降低吸收光能后用于电子传递的比例,而且会破坏叶黄素循环耗散过剩的光能,这也是D1蛋白周转对PSⅡ的保护作用大于叶黄素循环的原因之一。The effects of DI protein turnover and xanthophylls cycle on photosystem lI functions of Morus alba leaves under NaC1 stress were studied by using their inhibitors. The results showed that there were sound mechanisms of photoprotection in M. alba leaves and PS 11 reaction center remained high activity under 100 mmol· L-1 NaCl stress. PS 11 functions in SM or DTT treated leaves were damaged under NaCl stress. More severe damage occurred in SM treated leaves than that in DTT treated ones, which indicated D1 protein turnover and xanthophylls cycle played an important role in protecting PS 1I functions in leaves of M. alba under NaCl stress, and D1 protein turnover might play more important role than xanthophylls cycle. DTT treatment limited protection ability of the xanthophlly cycle in leaves of M. alba under NaC1 stress, but was able to reduce the damage of the excessive excitation energy to PS 11 reaction center by increasing dissipation of ineffective fluorescence and heat. SM not only damaged the xanthophylls cycle but also fluorescence and heat dissipation functions, leading to （1 -qp）/NPQ large accumulation and PS 1I reaction center deactivation. SM not only suppressed the D1 protein turnover, but also aggravated the QB reduction degree, which reduced the electronic transfer and the capacity of PQ. The decrease of PQ capacity ievitably depressed the thylakoid membrane functions establishing protons gradient （△pH） and limited the xanthophylls cycle that is dependent on △pH. In summary, inhibition of D1 protein turnover damaged xanthophylls cycle, which could interpret the reason why D1 protein turnover played more important role than xanthophylls cycle in protecting PS 11 functions in leaves of M. alba under NaCl stress.

关 键 词：桑树 NACL胁迫 D1蛋白周转 叶黄素循环 PSⅡ 

分 类 号：S722.33[农业科学—林木遗传育种] Q945.1[农业科学—林学]