Bonade-Bottino MA, Ceci LR, Gallerani R, Jouanin L
Dipartimento di Biochimica e Biologia Moleculare, Universita di Bari, Via Orabona 4, 70126 Bari, Italy (F.D.L., R.G.).
Plant Physiol. 1998 Nov;118(3):997-1004. doi: 10.1104/pp.118.3.997.
This work illustrates potential adverse effects linked with the expression of proteinase inhibitor (PI) in plants used as a strategy to enhance pest resistance. Tobacco (Nicotiana tabacum L. cv Xanthi) and Arabidopsis [Heynh.] ecotype Wassilewskija) transgenic plants expressing the mustard trypsin PI 2 (MTI-2) at different levels were obtained. First-instar larvae of the Egyptian cotton worm (Spodoptera littoralis Boisd.) were fed on detached leaves of these plants. The high level of MTI-2 expression in leaves had deleterious effects on larvae, causing mortality and decreasing mean larval weight, and was correlated with a decrease in the leaf surface eaten. However, larvae fed leaves from plants expressing MTI-2 at the low expression level did not show increased mortality, but a net gain in weight and a faster development compared with control larvae. The low MTI-2 expression level also resulted in increased leaf damage. These observations are correlated with the differential expression of digestive proteinases in the larval gut; overexpression of existing proteinases on low-MTI-2-expression level plants and induction of new proteinases on high-MTI-2-expression level plants. These results emphasize the critical need for the development of a PI-based defense strategy for plants obtaining the appropriate PI-expression level relative to the pest's sensitivity threshold to that PI.
这项研究表明，将蛋白酶抑制剂（PI）在植物中表达作为增强害虫抗性的一种策略，可能会产生潜在的不利影响。我们获得了不同水平表达芥菜胰蛋白酶PI 2（MTI - 2）的烟草（Nicotiana tabacum L. cv Xanthi）和拟南芥[Heynh.]生态型Wassilewskija）转基因植物。用这些植物的离体叶片喂养埃及棉铃虫（Spodoptera littoralis Boisd.）的一龄幼虫。叶片中高水平的MTI - 2表达对幼虫产生有害影响，导致死亡率增加和幼虫平均体重下降，并且与被吃掉的叶片表面积减少相关。然而，与对照幼虫相比，取食低表达水平MTI - 2植物叶片的幼虫死亡率并未增加，反而体重净增加且发育更快。低MTI - 2表达水平还导致叶片损伤增加。这些观察结果与幼虫肠道中消化蛋白酶的差异表达相关；在低MTI - 2表达水平的植物上现有蛋白酶的过表达以及在高MTI - 2表达水平的植物上新蛋白酶的诱导。这些结果强调了迫切需要为植物开发基于PI的防御策略，以获得相对于害虫对该PI的敏感性阈值而言合适的PI表达水平。
