Differentially Expressed Proteins Of Maize Leaves Under Drought Stress, Two-dimensional Electrophoresis And Mass Spectrometry Analysis

Drought is one of the most important abiotic constraints in maize (Zea mays L.)production. One drought tolerant and one drought sensitive inbred line were treated with 18%PEG to simulate drought treatment. Seventeen, Twenty-four and forty-eight hours later, leafsamples were collected from the same leaf position of the treated and control plants and usedfor protein extraction. The protein samples were separated by two-dimensionalelectrophoresis. The protein samples were separated by two-dimensional electrophoresis andanalysed for their expression change in response to drought stress. Peptide massfingerprinting of the drought induced proteins was assayed by MALDI-TOF-MS. The resultof MALDI-TOF was analysed with bioinformatics tools and rechecked with in silico cloning.The results are as follows: (1) Through comparison, the concentration of protein extractedwith the improved biolytics was as high as 3.8 μg/μl, 90% than before; better linearity wasobtained and proteins were better separated on two-dimension gels with 963 spots clearlydetected, 429 more than before; (2) For tolerant line "81565", the expression of 4, 9 and 2proteins were induced, the expression of 1, 0 and 2 proteins were inhibited, the expression of11, 15 and 3 proteins were increased, and the expression of 4, 3 and 6 proteins weredecreased at 17, 24 and 48 h of drought stress, respectively. For sensitive line "200B", theexpression of 2, 3 and 2 proteins were induced, the expression of 3, 2 and 4 proteins wereinhibited, the expression of 8, 10 and 2 proteins were increased, and the expression of 3, 3and 4 proteins were decreased at 17, 24 and 48 h of drought stress, respectively; (3) Theexpression of spot 2506, 3507 and 4506 was induced under drought stress. Their highestexpression amount was found at 24 h of drought stress. The result of peptide massfingerprinting analysis showed that spot 2506, 3507 and 4506 function as cinnamyl alcoholdehydrogenase, cytochrome protein 96A8 and S-adenosyl-L-methionine synthaserespectively; (4) The results of in silico cloning were aligned with maize genome and threesequences with E value of 0.0 and high score were detected. Because of the directrelationship between all these three functions and lignin biosynthesis, lignification of leafwas presumed to be a kind of active response of maize to drought stress.