盐胁迫对人工培养和野生地木耳光合作用的影响

The effects of salt stress on the photosynthesis in artificial cultlivated and wild nostoc commune

研究了盐胁迫对人工培养和野生地木耳光合活性的影响。结果表明:人工培养和野生地木耳光系统II最大光化学效率Fv/Fm,随着盐胁迫的增加,先缓慢下降(≤0.4 M NaCl)然后快速下降,在1 M NaCl时,分别显著下降42%和94%;其有活性的最大光系统I复合体数Pm在NaCl浓度低于0.8M时,维持相对稳定,但在1.5 M NaCl时,分别显著下降38%和68%;当NaCl浓度高于0.4M时,随着盐胁迫加剧,其光系统I实际光化学效率Y(I)持续降低,但围绕光系统I的环式电子传递Y(CEF)/Y(II)得到显著激发,如在1 M NaCl时,人工培养和野生地木耳分别显著增加到对照的15倍和19倍。由快速光响应曲线可知,在0.2 M NaCl条件下,野生地木耳围绕光系统II和光系统I的最大电子传递速率分别约是人工培养地木耳的4和6倍。该结果说明:相对于人工培养地木耳,野生地木耳在低盐胁迫下(≤0.2 M NaCl)具有更高的光合潜能,但在高盐胁迫下,其光合活性更敏感,能激发更高的环式电子传递来保护光合机构;两种状态的地木耳PSI比PSII更加耐受盐胁迫。

The effects of salt stress on the photosynthetic activity were investigated in the artificial and wild cultivated Nostoc Commune.The maximum quantum yield of PSII(Fv/Fm)of the artificial cultivated and wild Nostoc Commune,decreased slightly at 0.4 M NaCl,then with the increase of NaCl concentration,decreased sharply,specifically,by 42%and 94%respectively at 1 M NaCl;their maximum photo-oxidizable P700(Pm)had no significant changes at<0.8 M NaCl,but respectively significantly declined by 38%and 68%at 1.5 M NaCl;when NaCl concentration was higher than 0.4 M NaCl,the effective quantum yield of PSI Y(I)decreased gradually,their effective quantum yield of cyclic electron flow Y(CEF)/Y(II)were sharply increased,specifically,up to 15 and 19 times of the initial values at 1 M NaCl.From the rapid light curves,we found that the maximum electron transport rates around PSI and PSII in wild Nostoc Commune increased respectively about 4 and 6 times than those in artificial cultivated Nostoc Commune at 0.2 M NaCl.The results indicated that during the lower salt stress(0.2 M NaCl),the wild Nostoc Commune had higher photosynthetic capacity than the artificial cultivated Nostoc Commune;when exposed to higher salt stress,its photosynthetic activity was more sensitive,and its cyclic electron flow was more highly stimulated to protect photosynthetic apparatus than those of artificial cultivated colonies;the PSI was more tolerant to salt stress than the PSII in both artificial cultivated and wild Nostoc Commune.