Department of Plant Molecular Biology, University of Delhi, South Campus, New Delhi, 110021, India.
Transgenic Res. 2011 Apr;20(2):231-46. doi: 10.1007/s11248-010-9405-6. Epub 2010 Jun 15.
Osmotin and osmotin-like proteins are stress proteins belonging to the plant PR-5 group of proteins induced in several plant species in response to various types of biotic and abiotic stresses. We report here the overexpression of tobacco osmotin in transgenic mulberry plants under the control of a constitutive promoter (CaMV 35S) as well as a stress-inducible rd29A promoter. Southern analysis of the transgenic plants revealed the stable integration of the introduced genes in the transformants. Real-time PCR analysis provided evidence for the expression of osmotin in the transgenic plants under both the constitutive and stress-inducible promoters. Transgenic plants with the stress-inducible promoter were observed to better tolerate salt and drought stress than those with the constitutive promoter. Transgenic plants when subjected to simulated salinity and drought stress conditions showed better cellular membrane stability (CMS) and photosynthetic yield than non-transgenic plants under conditions of both salinity and drought stress. Proline levels were very high in transgenic plants with the constitutive promoter relative to those with the stress-inducible promoter. Fungal challenge undertaken with three fungal species known to cause serious losses to mulberry cultivation, namely, Fusarium pallidoroseum, Colletotrichum gloeosporioides and Colletotrichum dematium, revealed that transgenic plants with osmotin under control of the constitutive promoter had a better resistance than those with osmotin under the control of the stress-inducible promoter. Evaluation in next generation was undertaken by studying bud break in transgenic and non-transgenic plants under simulated drought (2% polyethylene glycol) and salt stress (200 mM NaCl) conditions. The axillary buds of the selected transgenic lines had a better bud break percentage under stressed conditions than buds from non-transgenic mulberry lines. A biotic assay with Bombyx mori indicated that osmotin protein had no undesirable effect on silkworm rearing and feeding. We therefore conclude that 35S transgenic plants are better suited for both abiotic stress also biotic challenges (fungal), while the rd29A transgenic plants are more responsive to drought.
渗透素和渗透素样蛋白是应激蛋白，属于植物 PR-5 蛋白组，可被多种植物物种诱导产生，以应对各种生物和非生物胁迫。我们在此报告，在组成型启动子（CaMV 35S）和应激诱导型 rd29A 启动子的控制下，烟草渗透素在转基因桑树植物中的过表达。对转基因植物的Southern 分析显示，引入的基因在转化体中稳定整合。实时 PCR 分析为在组成型和应激诱导型启动子下转基因植物中渗透素的表达提供了证据。在应激诱导型启动子下的转基因植物比在组成型启动子下的转基因植物更能耐受盐和干旱胁迫。在模拟盐度和干旱胁迫条件下，与非转基因植物相比，具有应激诱导型启动子的转基因植物显示出更好的细胞膜稳定性（CMS）和光合产量。与具有应激诱导型启动子的转基因植物相比，具有组成型启动子的转基因植物中的脯氨酸水平非常高。用三种已知会对桑树种植造成严重损失的真菌进行真菌挑战，即尖镰孢菌、胶孢炭疽菌和桑赤霉，结果表明，在组成型启动子控制下的具有渗透素的转基因植物比在应激诱导型启动子控制下的具有渗透素的转基因植物具有更好的抗性。通过在模拟干旱（2%聚乙二醇）和盐胁迫（200 mM NaCl）条件下研究转基因和非转基因植物的芽断裂来进行下一代评估。在胁迫条件下，选择的转基因系的腋芽的芽断裂百分比高于非转基因桑树系的芽断裂百分比。用家蚕进行的生物测定表明，渗透素蛋白对家蚕饲养和喂养没有不良影响。因此，我们得出结论，35S 转基因植物更适合应对非生物胁迫和生物挑战（真菌），而 rd29A 转基因植物对干旱的反应更为敏感。
