Different Exogenous Genes Enhanced The Resistant Ablity Of Potato Crops

1. A transgenic cultivar of sweet potato (TS) bearing Cu/Zn SOD and APX genes andnon-transgenic control cultivar (NT) were grown in pots under three different watertreatments, including control treatment (80%of soil moisture), moderate drought stress (60%of soil moisture) and serious drought stress (40%of soil moisture). The results showed that,the activities of SOD and APX, as well as the soluble sugar content were higher in TS than inNT, while POD showed an opposite manner. The activity of APX, contents of soluble sugarsand photosynthetic rates and transpiration rate are all declined in both sweet potato types withincreasing drought stress. Although the photosynthetic parameters decreased from20d to70dof stress in two plant types, photosynthetic rates have no significant difference between TSand NT. The yield formation of the two plant types showed highest under moderate stress andlowest under serious stress, respectively. Transgenic sweet potato has a higher yield formationand a smaller decrease tendency of yield formation under serious stress compared withnon-transgenic sweet potato. The stomatal conductances and transpiration rates of TS underthe three drought treatments were significantly lower than NT, which resulting in a higherWUE in TS. In conclusion, the genes of Cu/Zn SOD and APX could enhance the activities ofSOD and APX, the content of soluble sugar and the water use efficiency of transgenic potatoduring the formation of tuber under drought stress, thereafter, the yield formation could bebetter protected from drought stress.2. Potato is one of the most important food crops. Numbers of potato genotypes havebeen cultivated and widely cultured, especially in arid and semi-arid lands, hence, theresistance ability of potato is vital to fight against environmental stresses. In this experiment,we aimed to test five potato cultivars from different regions under drought, salt, hightemperature and oxidative stresses in order to select the cultivar which could possess strongerresistance capability when subjected to one or more stresses. According to our result, theChinese cultivar named LongShu NO.3(cv. LS) is tolerant to drought, salt and oxidative stressas it hashigher SOD and APX activities, stronger rooting ability and more root dry weight inPEG or NaCl treated groups; however, it is sensitive to high temperature. While the cultivarnamed ‘Superior’ is rather sensitive to drought and salt, compared to other cultivars, itstolerance to high temperature is best with steady growth status, Fv/Fm and water content inleaf, under42℃for24h. The rich anthocyanin contained cultivar JaYoung showed an overall excellent resistant ability to all stresses, and the important antioxidant, anthocyanin,might have played a crucial role.3. Glycinebetain, whose biosynthesis could be catalyze by choline oxidase (COD), is anextremely efficient compatible solute for scavenging oxidative stress-inducing molecules andprotecting the photosynthetic system in plants. To study the effects of CodA (a cholineoxidase) gene on the drought resistance and recovery, a transgenic potato cultivar (SC)bearing CodA gene and a non-transgenic (NT) control cultivar were raised in pots undermoderate and severe drought stress. The experiment was constituted by atwo-day-pretreatment with PEG20%and a four-day-water stress combined withtwo-day-recovery treatment. Under the four-day-water stress, plants were provided withnormal water condition, PEG10%and PEG20%. The results of pretreatment showed anexpression of CodA gene in transgenic potato and an accumulation of GB (glycine betaine);leaf water potential was higher in SC than in NT. In the stress-recovery-treatment, SC showedstronger antioxidant ability, more efficient photosynthetic system, higher chlorophyll content,lower MDA content and better recovery from water deficit stress than NT.4. Agrobacterium infection method is one of the mature methods that has been widelyused in the genetic transformation of potato (Solanum tuberosum). The Agrobacterium vectorused in this research is pCAMBIA2300, and firstly we transformed the gene of IbMYB1which has been cloned from sweetpotato into the Agrobacterium vector, then co-cultured theAgrobacterium with potato leave tissues via leaf disc method, induced the growth of calli andthe regeneration of calli in order to obtain the regenerated potato plants that might carry theexogenous gene. Through a plenty of tissue culture work, kanamycin screening and theanalysis of gene specific primer PCR, results proved that the exogenous gene has beensuccessfully insert into the potato genome and total11independent transgenic potato lineshave been obtained. Lastly, through a RT-PCR analysis after a short-term high temperaturestress, it confirmed that the exogenous gene of IbMYB1could expressed at the transcriptionallevel, and two lines with relatively higher gene expression level, SM5and SM12wereselected for further investigation.5. IbMYB1is a transcription factor that belongs to the R2R2-MYB family and regulatesthe biosynthesis of anthocyanin. In this study, the IbMYB1gene was introduced into potatoes.Two independent transgenic potato lines, SM5and SM12, were generated, and in conjunctionwith a control potato line transformed with an empty vector, the three lines were subjected tosalt stress. The results indicated that, the enhanced expression of IbMYB1reduced the saltstress-related damage impact on potato root growth in the NaCl contained MS medium, theroot dry weight was significantly higher than control. Moreover, when subjected to300mM NaCl for6days, the transgenic potato plants presented more secondary metaboliteconcentrations, stronger ROS scavenging ability and higher fluorescence parameterscompared with controls. These results imply a stronger salt tolerance in the transgenic potatolines. The expression levels of related genes in the flavonoid biosynthesis pathway were alsoimproved by the expression of IbMYB1under various abiotic stresses including drought, saltand UV-B sresses for6days.