死皮对橡胶树树皮线粒体超微结构及活性氧代谢的影响

为了解析橡胶树（Hevea brasiliensis）死皮的发生机制，有效进行死皮防治，以健康、轻度死皮、重度死皮橡胶树树皮为材料，研究死皮发生过程中树皮线粒体超微结构变化规律及活性氧（ROS）相关基因的表达模式变化。结果表明：死皮树线粒体超微结构发生不规则形变，膜内基质溶解，嵴消失，内腔空泡化等，且严重程度与死皮严重程度成正比。荧光定量PCR结果表明，过氧化物酶基因HbPOD2和HbPOD3在死皮树中的表达量高于健康树，可作为监测割胶强度、刺激强度和死皮发生的“标志”基因。植物细胞重要ROS清除酶过氧化氢酶基因HbCAT在死皮树中也下调表达，预示ROS产生与清除之间的平衡是影响橡胶树死皮发生的关键因素。橡胶树中重要抗氧化代谢物基因表达结果表明，HbGST1、HbGST2和HbPPO在死皮树中的表达量均高于健康树，可能与死皮发生过程胶乳原位凝固相关。本研究通过揭示死皮发生过程树皮超微结构和ROS相关基因表达模式变化，为阐明橡胶树死皮发生机制提供新观点，同时为进一步开发监测割胶强度、刺激强度和死皮发生的基因“标志”提供理论基础。

Effects of Tapping Panel Dryness on Mitochondrial Ultrastructure and ROS Metabolism in Barks of Rubber Tree (Hevea brasiliensis)

In order to elucidate the mechanism of tapping panel dryness（TPD） and effectively control it， the ultrastructure and the expression patterns of reactive oxygen species（ROS）-related genes in barks from healthy（H） and different degrees of TPD trees were studied in this study. The results showed that with the development of TPD， aberrant mitochondrial ultrastructure changed including the loss of the matrix， swelling of cristae， and the cavitation of the inner cavity were observed in barks. The results of qRT-PCR experiments showed that the expression levels of HbPOD2 and HbPOD3 in TPD trees were higher than those in healthy trees， indicating the possibility of these genes being used as “marker” genes to monitor the tapping intensity， the stimulation intensity， and the occurrence of TPD. The gene HbCAT was also down-regulated in TPD trees， indicating that the balance between ROS generation and scavenging may be a key factor in the occurrence of TPD in rubber tree. The expressions of HbGST1， HbGST2， and HbPPO in TPD trees were higher than those in healthy trees， indicating these genes may be associated with in-situ coagulation of latex during TPD occurrence. This study reveals the changes of ultrastructure and the expression patterns of ROS-related genes in rubber tree barks during TPD occurrence. These findings may provide a new perspective for elucidating the mechanism of TPD in rubber tree， and provid theoretical guidance for developing methods for monitoring tapping intensity and stimulation intensity and for developing TPD-related “marker” genes in rubber trees.