RESUMEN
Dehydrin gene transcript could be induced by heavy metals, and some dehydrins possess the ability to bind metals. However, the correlation between dehydrins and heavy-metal stress is unknown. In order to elucidate the contribution of dehydrins to heavy-metal stress tolerance in plants, we cloned two SK(2)-type dehydrin genes from heavy-metal hyperaccumulator Brassica juncea, and investigated their Cd/Zn tolerance in transgenic plants. Semi-quantitative RT-PCR analysis revealed that BjDHN2/BjDHN3 expressed in the leaves, stems and roots at a low level and were up-regulated by heavy metals. Antisense BjDHN3 Brassica juncea plants showed more electrolyte leakage and higher malondialdehyde production than the control plants when exposed to heavy metals, and the total amount of metals accumulated in the whole plant was reduced. Transgenic tobacco plants overexpressing BjDHN2/BjDHN3 showed lower electrolyte leakage and malondialdehyde production than the control plants when exposed to Cd/Zn. These results indicated that BjDHN2/BjDHN3 enhanced the tolerance for heavy metals by reducing lipid peroxidation and maintaining membrane stability in the plants.
Asunto(s)
Metales Pesados/farmacología , Planta de la Mostaza/efectos de los fármacos , Planta de la Mostaza/metabolismo , Proteínas de Plantas/metabolismo , Secuencia de Aminoácidos , Secuencia de Bases , Regulación de la Expresión Génica de las Plantas/efectos de los fármacos , Datos de Secuencia Molecular , Planta de la Mostaza/genética , Proteínas de Plantas/genética , Proteínas de Plantas/aislamiento & purificación , Alineación de Secuencia , Nicotiana/genética , Nicotiana/crecimiento & desarrollo , Nicotiana/metabolismo , Regulación hacia Arriba/efectos de los fármacosRESUMEN
Thlaspi caerulescens L. is well known as a Zn/Cd hyperaccumulator. The genetic manipulation of T. caerulescens through transgenic technology can modify plant features for use in phytoremediation. Here, we describe the efficient transformation of T. caerulescens using Agrobacterium tumefaciens strain EHA105 harboring a binary vector pBI121 with the nptII gene as a selectable marker, the gus gene as a reporter and a foreign catalase gene. Based on the optimal concentration of growth regulators, the shoot cluster regeneration system via callus phase provided the basis of the genetic transformation in T. caerulescens. The key variables in transformation were examined, such as co-cultivation period and bacterial suspension density. Optimizing factors for T-DNA delivery resulted in kanamycin-resistant transgenic shoots with transformation efficiency more than 20%, proven by histochemical GUS assay and PCR analysis. Southern analysis of nptII and RT-PCR of catalase gene demonstrated that the foreign genes were integrated in the genome of transformed plantlets. Moreover, the activity of catalase enzyme in transgenic plants was obviously higher than in wild-type plants. This method offers new prospects for the genetic engineering of this important hyperaccumulator species.