Improvement Of Drought And Salt Tolerance Using Arabidopsis BOUNTIFUL And HARDY Gene And Epicuticular Wax Synthesis Genes In Tomato

The extreme changes of global environment and climate, especially the drought stress and soilsalinization frequently happened, lead to crop yield decrease. To cope with the double pressure of future,genetic engineering was adopted for crop improvement. Genetic engineering not only saves time andeffort, avoids genetic linkage drag, but pyramides several resistance genes quickly, providing aneffective way for crop genetic improvement. Tomato is one of the most important vegetables, playing animportant role in people’s daily life, sensitive to drought and moderate sensitive to salt. The purpose ofthis study was to transfer BOUNTIFUL gene and HARDY gene via Agrobacterium-mediatedtransformation and screen for drought and salt tolerance of the transgenic plants, which is thefoundation of genetic improvement of drought and salt tolerance. In addition, the progenies of the CER1,CER6, SHN1and WAX2transgenic plants were treated with salt and drought stress and inoculated withB. cinerea and P.infestans in order to identify the abiotic and biotic stresses response caused by thealteration of cutin and wax. The main contents and results in this study are as follows:1. BOUNTIFUL gene from Arabidopsis transferred to tomato cultivar Moneymaker and M82viaAgrobaterium-mediated transformation. Transgenic plants showed compact and erect growth habit withwinkled small and thick leaves. Epedimeral cell area of transgenic plants increased compared with wildtype. GUS staining, PCR, RT-PCR and southern blot had verified the intergration and expression ofBOUNTIFUL gene in tomato genome. Salt and drought stresses had been conducted on the T2oftransgenic plants. Under drought stress, survival percentage, plant water content and growth parametersof moneynaker transgenic plants improved significantly compared with wild type. The survivalpercentage and plant water content of M82transgenic plants increased significantly under once droughtstress, whereas most of the growth parameters showed no difference. Under three times drought stress,survival percentage, water content and growth parameters showed no difference compared with wildtype. Under salt stress, survival percentage, plant water content and growth parameters of M82transgenic plants improved significantly compared with wild type. Survival percentage, plant watercontent and most growth parameters of Moneymaker transgenic plants showed no difference. With theabove results, the salt and drought tolerance of Moneymaker transgenic plants and M82transgenicplants depended on the geneyic background.2. HARDY gene, an Arabidopsis AP2/ERF transcription factor, was transferred to tomato cultivarMoneymaker. Molecular detection and identification of salt and drought tolerance was conducted ontransgenic plants. Integration and expression of HARDY gene has been verified through PCR, RT-PCRand southern blot. Under drought stress, survival percentage, plant water content and growth parametersof transgenic plants were significantly improved compared with wild type. Under salt stress, survivalpercentage of transgenic plants increased, plant water content and growth parameters showed nodifference.3. Hybridiztion was conducted on BOUNTIFUL plants and HARDY plants to get BFL+HRD plants. Drought and salt stress were imposed on BFL+HRD plants. Though the drought tolerance of BFL+HRDplants improved significantly compared with wild type, the level of improvement was not as high asBOUNTIFUL plants and HARDY plants. Under250mM NaCl, survival percentage and a few growthparameters increased compared with wild type. Under300mM NaCl, survival percentage and growthparameters showed no difference compared with wild type.4. Four Arabidopsis gene, CER1, CER6, SHN1and WAX2known to be involved in cuticular waxsynthesis were overexpressed in tomato cultivar M82. B. cinerea and P. infestans resistance, salt anddrought tolerance in seedling stage were evaluated in selfed progeny of these transgenic plants. Whencompared with control M82, transgenic plants were to some extent more resistant to P. infestans andmore susceptible to B. cinerea. All transgenic plants showed an improved level of salt tolerance in termsof survival percentage and growth parameters. The resistance to drought stress is complicated, whichmight be related to the functions of the genes.