The Effect Of Thylakoid Membrane Lipid Composition On Drought Resistance In Tomato

Drought is a major environmental factor limiting the plant growth, development and yield. The biomembrane was regarded as the position which is firstly suffered damage under drought stress, and fatty acid composition in thylakoid membrane is related to the tolerance of drought stress. Omega-3 fatty acid desaturase was the key enzyme which catalyzed 18:2 to form 18:3. The change of its content can influence the composition of membrane lipid. Then it can change the tolerance of drought stress.WT and sense-transgenic lines T(+)-12 of tomato were used to measure the fatty acid composition of thylakoid membrane, superoxide dismutase, osmotic solutes, photosynthetic and chlorophy a fluorescence parameters under drought stress. The main results are as follows:1. Compared with WT plants,the T(+)-12 had low content of 18:2 and high content of 18:3. It resulted in the increase of unsaturated level of membrane lipids in sense transgenic plants. The T(+)-12 had low content of phospholipids and high content of glucolipid.2. Under drought stress, the T(+)-12 of tomato could maintain higher water potential. Water potential in the T(+)-12 of tomato decreased slower.3. Under drought stress, the T(+)-12 of tomato could maintain higher photosynthetic capacity. The maximal photochemical efficiency of PSâ…¡(Fv/Fm) and photosynthetic rates(Pn) in T(+)-12 lines with higher 18:3 decreased less under drought stress. Compared with WT, the maximal photochemical efficiency of PSâ…¡(Fv/Fm) and photosynthetic rates(Pn) in the T(+)-12 of tomato decreased slower.4. Under drought stress, the T(+)-12 of tomato could maintain lower membrane lipid peroxidation. Compared to WT, the sense-transgenic lines could maintain higher activities of antioxidant enzymes.5. Under drought stress, the T(+)-12 of tomato could maintain lower cytomembrane permeation rate. The T(+)-12 of tomato could maintain lower electric conductivity, injury and the content of MDA. 6. Under drought stress, the T(+)-12 of tomato could maintain higher the content of proline and sugar.7. Under drought stress, the T(+)-12 of tomato could maintain higher germination capacity.Those results indicated that higher unsaturation of thylakoid membrane lipids enhanced the tolerance of tomato photosynthetic apparatus to drought stress.