Zhao Aiping, Li Yin, Leng Chunmeng, Wang Ping, Li Yiping
Key Laboratory of Plant Protection Resources and Pest Management, Ministry of Education, Northwest A&F University, Yangling, China.
State Key Laboratory of Crop Stress Biology for Arid Areas, Northwest A&F University, Yangling, China.
Front Physiol. 2019 Jan 15;9:1963. doi: 10.3389/fphys.2018.01963. eCollection 2018.
L. (diamondback moth) is a pest of cruciferous plants. To understand the relationship among protease inhibitors, protease activities and the growth and development of this insect, the activities of midgut proteases of larvae were determined in this study. Protease samples were extracted from the midguts of larvae, and the protease activities were determined using enzyme specific substrates. The results showed that CaCl, EDTA, and EGTA inhibited only the trypsin. Among the common protease inhibitors, phenylmethyl sulfonyl fluorine (PMSF), Nα-p-methyl sulfonyl-L-lysine chloromethylketone (TLCK), Nα-methyl sulfonyl-L- phenylalanine chloromethyl ketone (TPCK), soybean trypsin inhibitor (STI), and PMSF inhibited the total protease, high-alkaline trypsin (a trypsin subtype with highly alkaline pH optimum), low-alkaline trypsin (another trypsin subtype with slightly alkaline pH optimum), and chymotrypsin; TLCK inhibited the total protease and high-alkaline trypsin, whereas TPCK only activated the high-alkaline trypsin activities. STI had an inhibitory effect on all the proteases. These results showed that protease inhibitors had a certain extent inhibition to protease activities in the larval midgut of and that STI can potentially be used for effective pest control. The development of was delayed in the presence of different inhibitors. These effects were also related to the concentration of the inhibitor. A higher STI concentration showed a longer lasting effect but lower effect in this study compared to that of TLCK. The protease inhibitors had some inhibitory effect on the synthesis and secretion of proteases, and interfered with the protease activity, thereby inhibiting the absorption of nutrients and delaying the growth and development of and reducing their ability to reproduce. These findings should provide the baseline information about using for effective pest management in the future.
小菜蛾是十字花科植物的一种害虫。为了解蛋白酶抑制剂、蛋白酶活性与该昆虫生长发育之间的关系，本研究测定了小菜蛾幼虫中肠蛋白酶的活性。从幼虫中肠提取蛋白酶样品，并使用酶特异性底物测定蛋白酶活性。结果表明，氯化钙、乙二胺四乙酸（EDTA）和乙二醇双四乙酸（EGTA）仅抑制胰蛋白酶。在常见的蛋白酶抑制剂中，苯甲基磺酰氟（PMSF）、Nα-对甲苯磺酰-L-赖氨酸氯甲基酮（TLCK）、Nα-甲基磺酰-L-苯丙氨酸氯甲基酮（TPCK）、大豆胰蛋白酶抑制剂（STI）和PMSF抑制总蛋白酶、高碱性胰蛋白酶（一种最适pH值为高碱性的胰蛋白酶亚型）、低碱性胰蛋白酶（另一种最适pH值为微碱性的胰蛋白酶亚型）和糜蛋白酶；TLCK抑制总蛋白酶和高碱性胰蛋白酶，而TPCK仅激活高碱性胰蛋白酶的活性。STI对所有蛋白酶都有抑制作用。这些结果表明，蛋白酶抑制剂对小菜蛾幼虫中肠的蛋白酶活性有一定程度的抑制作用，并且STI有可能用于有效的害虫防治。在存在不同抑制剂的情况下，小菜蛾的发育会延迟。这些影响也与抑制剂的浓度有关。在本研究中，较高浓度的STI显示出持续时间更长但效果较低的作用，与TLCK相比。蛋白酶抑制剂对蛋白酶的合成和分泌有一定的抑制作用，并干扰蛋白酶活性，从而抑制营养物质的吸收，延缓小菜蛾的生长发育并降低其繁殖能力。这些发现应为未来有效进行害虫管理提供基线信息。
