The Responses Of Photosynthesis In Tobacco With The BADH Gene To Drought And Strong Light Stresses

Glycinebetaine(GB) is a compatible solute that accumulates in certain plants and microorganisms in response to various types of stress.we demonstrated previously that, when the tobacco(Nicotiana tabacumL.) is transformed with the BADH gene for betaine aldehyde dehydrogenase from spinach(Spinacia oleracea L.),the genetic engineering enabled the plants to accumulate glycinebetaine mainly in chloroplasts, and resulted in enhanced tolerance to high temperature stress during growth of young seedlings. In the present study, we attemped to elucidate the mechanism whereby synthesis of betaine protects the the transgenic tobacco plants with BADH gene against drought or strong light stress.The response of photosynthesis in tobacco with the BADH gene to drought and strong light stress were studied .The main results are as follows:1. Effects of drought-stress on thylakoid lamella ultrastructure of tobacco leaves:Thylakoid lamella of tobacco leaves became swollen and difficult to distinguish under drought stress, and those changes were more significant in wild tobacco than in transgenic tobaco. The BADH gene could protect thylakoid lamella of transgenic tobacco leaves from drought stress.2. Effects of drought-stress on lipid content in the thylakoid membrane of tobacco leaves:The monogalactosyl diaylglycerol (MGDG), digalactosyl diacylglycerol (DGDG) and phosphatidylglycerol (PG) contents of the tobacco decreased significantly under drought stress; the digalactosyl...