桉树枝瘿姬小蜂体内两种优势细菌对桉树组培苗叶片部分生理指标的影响

Effects of Two Species of Dominant Bacteria in Leptocybe invasa on Some Physiological Indexes of Leaves of Eucalyptus Tissue Culture Seedlings

本试验研究了桉树枝瘿姬小蜂体内两种优势细菌(E4、N14)对桉树组培苗叶片光合生理、叶绿素荧光特性及渗透调节物质含量的影响,以期为阐明桉树枝瘿姬小蜂与寄主桉树的互作关系及建立该害虫的生物防治方法提供参考。试验以等量体积清水为对照(CK),设置10 mL稀释的E4菌液(E4)、10 mL稀释的N14菌液(N14)、两种稀释菌液各5 mL的混合菌液(E4+N14)处理,均匀喷洒桉树组培苗叶片,喷洒结束7 d后测定各项生理指标。结果表明,E4处理的游离脯氨酸(PRO)、叶绿素含量(Chl a、Chl b、Chl a+b)、净光合速率(Pn)、水分利用效率(WUE)、PSⅡ实际光量子产量(Yield)、光化学猝灭系数(qP)、非光化学猝灭系数(qN)、PSⅡ相对电子传递速率(ETR)均显著高于CK,可溶性蛋白含量和胞间CO_(2)浓度(Ci)显著低于其它处理,其余指标相比CK无显著变化。N14处理的渗透调节物质、丙二醛(MDA)含量显著高于CK;叶绿素各指标低于CK,且除Chl b含量外,均与CK差异显著;除Ci显著高于CK外,光合和叶绿素荧光参数均显著低于CK。E4+N14处理各项指标总体来说介于E4和N14处理之间,且多数与CK差异不显著。相关性分析结果表明,Ci与渗透调节物质含量呈正相关,而与其余光合作用指标和叶绿素荧光参数呈负相关;渗透调节物质含量与叶绿素含量、除Ci外的光合特性、叶绿素荧光参数均呈负相关;除Ci外,叶绿素含量、光合特性和叶绿素荧光参数间均呈正相关关系;但指标间的相关程度不同。表明两种桉树枝瘿姬小蜂体内优势细菌中,E4倾向于提高桉树组培苗叶片的光合生理指标,降低渗透调节物质含量,而N14作用相反,两种菌的混合液作用介于两种单菌处理之间,均在一定程度上影响着桉树正常生理代谢平衡。

In this paper, we studied the effects of two species of dominant bacteria(E4 and N14) in Leptocybe invasa on photosynthetic physiology, chlorophyll fluorescence properties and content of osmotic adjustment substances in leaves of eucalyptus seedlings, in order to clarify the interaction between Leptocybe invasa and host eucalyptus and provide a reference for biological control of the pest. The experiment designed four treatments as spraying equal volume of clear water(CK), spraying 10 mL diluted E4, spraying 10 mL diluted N14, and spraying 5 mL E4 and 5 mL N14(E4+N14). They were evenly sprayed on eucalyptus leaves, and the physiological characters were measured on the 7 th day after spraying. The results showed that the contents of free proline(PRO) and chlorophyll(Chla, Chlb, Chla+b), net photosynthetic rate(Pn), water use efficiency(WUE), PSⅡ actual light quantum yield(Yield), photochemical quenching coefficient(qP), nonphotochemical quenching coefficient(qN), PSⅡ relative electron transfer rate(ETR) under E4 treatment were significantly higher than those of CK, while the soluble protein content and intercellular CO_(2) concentration(Ci) were significantly lower than those of the other treatments;other characters had no significant change compared with CK. Under N14 treatment, the content of osmoregulation substances and malondialdehyde(MDA) was significantly higher than those of CK;the chlorophyll characters were lower compaired with CK, and reached significant level except Chl b;except Ci, the photosynthetic and chlorophyll fluorescence parameters were significantly lower than those of CK. All the characters of E4+N14 treatment were generally between E4 and N14 treatment, and most were not significantly different from those of CK. The correlation analysis results showed that Ci was positively correlated with osmotic regulatory substances, but negatively correlated with the other photosynthetic indexes and chlorophyll fluorescence parameters. The contents of osmotic regulating substances were negatively correlated with chlorophyll content, photosynthetic characteristics except Ci, and chlorophyll fluorescence parameters;there were positive correlations between chlorophyll content, photosynthetic characteristics and chlorophyll fluorescence parameters except Ci, but the correlation degrees were different. In conclusion, E4 treatment tended to increase the photosynthetic parameters of the eucalyptus leaves and reduce the contents of osmoregulation substances, while N14 had the opposite effects. The mixed solution of the two bacteria species had the effects between the two single-bacterium treatments. They all affected the normal physiological metabolic balance of eucalyptus to a certain extent.