Study On Saline-alkali Tolerance Of TaCHP Transgenic Wheat

Wheat is a glycophyte. Soil salination is one of the most limiting factors in wheat growth, development and yield. With the development of molecular biology, using transgenic technology to generate saline-alkaline tolerance wheats has become a new way of genetic breeding.On the basis of previous studies, after antibiotics screening and molecular identifications, we have obtained two kinds of TaCHP transgenic wheat:T6 generation transgenic wheat lines No.25-2-5 and No.33-2-3, derived from Agrobacterium inoculum to shoot apical meristem of common wheat seedlings Jinan 17 (named JN 17) and T4 transgenic lines No.21-1-3、No.26-12-5 and No.27-6-8, derived from Agrobacterium-mediated transformation of common wheat Zhoumai 22 (named Zhou 22).The following experiments were performed:1、In the laboratory, the transgenic seeds and their non-transgenic controls were used for germination and seedling growth analysis under conditions of salt (NaCl), alkaline salt (NaHCO3:Na2CO3,=9:1) and the mixture of the above salt and alkaline salt.2、Seed germination and early seedling growth experiments were performed in nutrient soil and saline-alkali soil.3、In the common soil and saline-alkali soil test fields, the growth and development indexes of transgeniclines (seedlings, seedling establishment and filling stages) were observed and recorded, respectively. Physiochemical parameters were measured, and the correlation between yield and the above indexes were analyzed.4、In gradient salt pool and alkali experiment pool, the agronomic traits of T4 transgenic lines were analyzed.The main results are as follows:1、At seedling stage, two kinds of transgenic lines had greater NaCl tolerance, while no significant difference was observed between transgenic lines and their non-transgenic controls when treated with alkaline salts aqueous solution. For the mixture NaCl and (NaHCO3:Na2CO3=9:1) alkaline salt, the growth status of two kinds of transgenic lines showed little difference with their controls in {25 mM NaCl+50 mM alkaline salts (NaHCO3:Na2CO3=9:1)}, while the relative plumule length of transgenic lines were longer than their controls when treated with{(50 mM NaCl+25 mM (NaHCO3:Na2CO3=9:1)}, respectively. As seedlings, transgenic lines had better performance on saline-alkali tolerance compared to their controls.2、Seeds of transgenic and non-transgenic control began to germinate in 12-16 h and almost all seeds germinated at the 4th day after dibbling in nutrient soil, and the seedlings grew slowly in the next few days. Germination of seeds was delayed in saline-alkali soil than that in nutrient soil, and the germination rates of transgenic lines were better than their controls. After 20 days of growth, the biomass of transgenic seedlings had little difference with the control when grown in nutrient soil, but in saline-alkali soil, the biomass of transgenic lines were slightly higher than their parents.3、Except for the seedling roots at seedling establishment stage, the physiochemical parameters analysis showed that the K+/Na+ ratio of leaves and roots of all transgenic lines was significantly higher at all growth stages in saline-alkali test fields than that in common soil. MDA content in two kinds of transgenic lines was significantly lower in both leaves and roots than their controls (with leaves of seedling establishment stage as an exception), but were elevated clearly during three key growth stages in saline-alkali soil.4、In the common soil test field, the grain yield of two kind of transgenic lines has higher grain yield than their control, respectively. But no significant differences were observed among three transgenic lines and their parent Zhou 22. It also showed that the number of spikelet and tiller were more correlated to grain yield. While, all transgenic lines had higher grain yield than their independent control when growing in saline-alkali soil test field. It was confirmed that the flag leaf length and the number of spikelet were correlated positively to grain yield, while plant height showed negatively correlation.5、Agronomic traits analysis showed that the output of transgenic lines was positively correlated to the concentration of salt and alkali in a certain range, which growing in gradient salt and alkali pool. When the concentration of salt and alkali reached to their maximum {0.8% NaCl,80 mM (NaHCO3:Na2CO3=9:1)}, the grain yield of transgenic lines was higher than their parent control Zhou 22. The output of three transgenic lines, which planted in salt pool, was 1.03,1.37 and 1.16 times than control Zhou 22, respectively. In 80 mM alkaline salt pool, the thousand seed weight of transgenic lines was 1.18,1.37 and 1.5 times of control.As described above, various parameters of germination and seedling growth of two groups of transgenic events were better than their individual controls in the laboratory under saline conditions. Many physiochemical parameters confirmed that all transgenic lines protected their plasma membranes from salt and alkali stress by adjusting homeostasis of concentration of ions as well as ROS-scavenging enzyme activates. The results could provide new knowledge of recognizing the mechanism of plant in response to salt stress.