Change Of Lignin Content In Leaf Of Maize Inbred Lines Under Drought Stress And Its Relationship With Drought Tolerance

Maize originates from the tropical zone of high temperature and humidity in Central and Southern America,so that it has poor tolerance to drought. In recent years ,because of the lack of water resources,drought has become the major limitative factor to maize production. Take two inbred lines "81565" and "200B" as material,the differences of protein express were studied under drought stress. One of the spost was studied for the results of key enzyme of lignin biosynthesis—cinnamyl alcohol dehydrogenase (CAD). But the change of lignin content in leaf of maize inbred lines under drought stress and its relationship with drought tolerance did not study.So, firstly, take six inbred lines ("81565", "200B","87-1",18-599","18-599M" and "ES40") as material. Leaf lignin content was assayed with 6 inbred lines of different drought tolerance under strong and moderate drought stress as well as well-watered control, and converted into drought tolerant coefficient. Correlation analysis was made between drought tolerant coefficients of leaf lignin content and per plant grain yield as well as anthesis-silking interval. The results showed that significant difference was found in the response of leaf lignin content of inbred lines with different drought tolerance to drought stress. Under drought stress, the leaf lignin content of highly tolerant inbred lines increased significantly with a high average drought coefficient, the leaf lignin content of intermediate tolerant inbred lines increased slightly, while the leaf lignin content of drought sensitive inbred lines matched with the well-watered control or decreased slightly. Under the strong and moderate drought stress, significant correlation coefficients (r = 0.848 and r = 0.889) were estimated between the average drought tolerant coefficient of leaf lignin content and the drought tolerant coefficients of per plant grain yield and anthesis-silking interval.As for the above analysis of the results of field,the express of CAD gene under drought stress was studied with QRT-PCR. four inbred lines ("81565","200B","87-1" and "Dan340") were treated with 18% PEG to simulate drought treatment, as well as well-watered control. At zero, six, twelve, twenty-four and thirty-six hours later, the leaf was sampled from each plant and used to extract total RNA with TRIZOL agent kit (Invitrogrn). The integrity of the total RNA samples was analysyed with QRT-PCR. The results showed that the relative expression of CAD gene of four inbred lines were changed under drought streatment. "81565" and "87-1" were in the peak at 24h, "Dan340" has been on a steady downward trend, but the expression of "200B" increased after 24 h.So,"200B" and "81565" are strong inbred lines, "87-1" and "18-599M" are moderate inbred lines, "18-599"and "ES340" are sensitive inbred lines. Maize can resist drought though its owm lignin biosynthesis of leaves while under water stress.