华南205木薯二倍体及其同源四倍体对朱砂叶螨取食胁迫的生理响应

为明确木薯同源四倍体抗螨的生理机制，以华南205（South China 205，SC205）木薯的二倍体及其同源四倍体为试验材料，分别于朱砂叶螨Tetranychus cinnabarinus取食胁迫前（取食0 d）及取食胁迫后1、4和8 d观察两个倍性植株叶片的受害情况并测量叶片中叶绿素、游离脯氨酸、丙二醛（malondialdehyde，MDA）、次生代谢物质含量和主要保护酶活性的变化。结果显示，朱砂叶螨取食胁迫后SC205四倍体叶片受害情况较SC205二倍体的轻；取食胁迫后1、4和8 d木薯SC205四倍体叶片中叶绿素含量下降幅度比SC205二倍体的小；取食胁迫后1、4和8 d两个倍性木薯叶片中MDA和游离脯氨酸含量均呈上升的趋势，其中SC205四倍体叶片中MDA含量的上升幅度比SC205二倍体的小，而游离脯氨酸含量的上升幅度比SC205二倍体的大；取食胁迫后1、4和8 d两个倍性木薯叶片中过氧化氢酶（catalase，CAT）、超氧化物歧化酶（superoxide dismutase，SOD）、过氧化物酶（peroxidase，POD）活性和单宁、总酚、总黄酮含量较取食胁迫前均显著上升，且SC205四倍体的上升幅度比SC205二倍体的大。表明木薯同源四倍体植株的抗螨性与叶绿素、游离脯氨酸、MDA、保护酶活性及次生代谢物质含量变化有关，它们均参与了木薯对朱砂叶螨取食胁迫的诱导型防御反应。

Physiological responses of cassava SC205 diploids and their autotetraploids to feeding stress by carmine spider mite Tetranychus cinnabarinus

To clarify the physiological mechanisms underlying mite resistance in cassava autotetraploids, diploids, and their autotetraploids of South China 205 (SC205) cassava were used as test materials. Subsequently, the damage to leaves, chlorophyll content, free proline content, malondialdehyde (MDA) levels, secondary metabolite content, and activity of main protective enzymes were compared following feeding stress by carmine spider mite Tetranychus cinnabarinus for 0, one, four, and eight days. The results showed that leaves of SC205 autotetraploids exhibited lighter damage compared to SC205 diploids following feeding stress by T. cinnabarinus. Furthermore,the decrease in chlorophyll content in SC205 autotetraploid leaves was less pronounced than in SC205 diploids after one, four, and eight days of feeding stress. In addition, MDA and free proline contents in cassava leaves of both ploidies increased after one, four, and eight days of feeding stress. Specifically, the increase in MDA content was smaller in SC205 autotetraploids compared to SC205 diploids, while the increase in free proline content was larger. Moreover, activities of catalase, superoxide dismutase, peroxidase, and the contents of tannins, total phenols, and total flavonoids in cassava leaves significantly increased after one, four, and eight days of feeding stress compared to pre-feeding levels. Interestingly, the increase in SC205 autotetraploids was greater than in SC205 diploids. These results indicate that the resistance of autotetraploid cassava plants to mites is associated with changes in chlorophyll content, free proline content, MDA levels, protective enzyme activity, and secondary metabolite content, all of which are involved in the induced defensive response of cassava to T. cinnabarinus feeding stress.