Comparative Study On Ion Homeostasis And Salt Resistance Of Wild Tomato And Cultivated Tomato

The soil salinization is one of the important factors that restrict the plant growth and agricultural production in arid, semi-arid and coastal areas. Most crops, including tomatoes, are great sensitive to salt stress during their individual growth and development. Due to the complex mechanism of plant salt tolerance and the obscure appraisal index of the plant salt tolerance, more studies about plant salt tolerances need to carry out. In the present research, the effects of different levels of salinity on plant biomass, photosynthesis, K+ and Na+ in organs, tissue and cells, as well as the allocation in the blade apoplast and symplasm and so on, were studied by using wild tomato(Lycopersicon pimpinellifolium), cherry tomato (Lycopersicon esculentum), cultivated tomato (Lycopersicon esculentum) and their hybrid tomato. The main results are as follows:Compared with the control, salinity inhibited the growth of tomato varieties significantly. Under salt stress, the growth inhibition of wild tomato was the least, and the inhibition of cultivated tomato was the heaviest. The inhibition of cherry tomato was between the above mentioned tomatoes. It also suggested that the salt tolerance of F1 surpassed the parent. The photosynthesis of each tomato leaves was decreased under NaCl stress, and no significant difference was existed in their decrease. K+ content of different tomato plants were markedly decreased, and their Na+ content were increased significantly.The increased Na+ mainly accumulated in the plant shoot. However, the Na+ increase of wild tomato was significantly lower than that of cultivated tomato and their hybrid tomato, the K+/Na+ decline of wild tomato was less than that of cultivated tomato and their hybrid tomato. Under salinity, wild tomato and hybrid tomato could take Na+ to the phloem cells, or save it in the myeloid cells to avoid a lot of Na+ go into xylem. It could make the Na+ level at low levels in shoot. Under the treatment of the NaCl, the ratio of "[Na+]symplast/[Na+]apoplast" and "[K+] symplast/[K+] apoplast" in functional leaves of wild tomato were higher than that of cultivated tomato and hybrid tomato; while the K+ concentrations of the apoplast in cultivated tomato leaves was significantly increased.In general, the present study indicated that, under the condition of salt stress, as can be seen from the organ and cell levels, the lower Na+ accumulation and higher K+ absorption lead to higher salt tolerance of wild tomato. But based on the distribution of the apoplast and symplast, under the condition of salt stress, the more proportion of K+ and the lower Na+ were existed in leaf symplast lead to higher salt tolerance of wild tomato. However, the hybrid tomato is inclined to the distribution characteristics of male parent (wild tomato).