The Regulation of Mung Bean CYP90A2 Gene Expression and the Proteomes of Brassinosteroid- mediated Epicotyl Elongation under Chilling Stress

• Main Authors: Bin Huang, 黃斌
• Other Authors: Yih-Ming Chen
• Format: Others
• Language: zh-TW
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/91355194319428933965

博士 === 國立臺灣大學 === 植物科學研究所 === 94 === Mung bean CYP90A2 is a putative brassinosteroid (BR) synthetic gene that shares 77 % identity with the Arabidopsis CPD gene. The transcriptions of CYP90A2 are abundantly detected in leaves that increase following seedlings development and exhibit diurnal variation. CYP90A2 is feedback down regulated in the existence of BR. When exposed to 10 ℃ chilling stress, Arabidopsis shows higher growth than mung bean and the expression of Arabidopsis CYP genes are higher than mung bean CYP90A2. Therefore, chilling-inhibited growth and survival rate could be improved by exogenous treatment of BR. In the proteomic study of BR-promoted epicotyl elongation, BR-treated mung bean epicotyls had 31 up-regulated and 24 down-regulated protein spots. Identifications of these proteins using mass spectrometry (MALDI-Q-TOF MS/MS) analysis suggest that most were involved in cell growth, photosynthesis and respiration. In the physiological assay, BR promotes epicotyl elongation only under high light condition, while inhibits elongation under full darkness condition. With regard to interaction of the BR proteome and chilling stress, 17 chilling down-regulated proteins were re-up-regulated by BR treatment. The up-regulated proteins are involved in methionine assimilation, ATP synthesis, and cell growth. This is consistent with the re-up-regulation of methionine synthase and S-adenosyl-L-methionine synthetase, since chilling-inhibited mung bean epicotyl elongation could be partially recovered by exogenous treatment of DL-methionine. In summary, this is the first proteomic mapping established in mung bean, and the regulation between brassinosteroid and chilling response is investigated, to which, possible mechanisms are revealed.