Transgene Pyramiding of theHVA1andmtlDin T3 Maize (Zea maysL.) Plants Confers Drought and Salt Tolerance, along with an Increase in Crop Biomass

摘要

The pBY520 containing theHordeum vulgare  HVA1regulated by the rice actin promoter (Act1 5′) or the JS101 containing the bacterial mannitol-1-phosphate dehydrogenase (mtlD) also regulated by riceAct1 5′and a combination of these two plasmids were transferred into the maize genome, and their stable expressions were confirmed through fourth generations. Plants transcribing a combination of theHVA1+mtlDshowed higher leaf relative water content (RWC) and greater plant survival as compared with their single transgene transgenic plants and with their control plants under drought stress. When exposed to various salt concentrations, plants transcribing theHVA1+mtlDshowed higher fresh and dry shoot and dry root matter as compared with single transgene transgenic plants and with their control plants. Furthermore, the leaves of plants expressing themtlDaccumulated higher levels of mannitol. Plants expressing theHVA1+mtlDimproved plant survival rate under drought stress and enhanced shoot and root biomass under salt stress when compared with single transgene transgenic plants and with their wild-type control plants. The research presented here shows the effectiveness of coexpressing of two heterologous abiotic stress tolerance genes in the maize genome. Future field tests are needed to assure the application of this research.