RESUMO
Plants respond to cold stress by modifying the expression of a battery of cold-responsive genes. Using cDNA-AFLP techniques, GMCHI (G lycine m ax chilling-inducible) (accession no. EU699765) was isolated from the embryonic axis of a chilling-resistant cultivar of soybean seed imbibed at 4 degrees C for 24 h. The full-length GMCHI cDNA which consisted of a single open reading frame (ORF) encoded a putative polypeptide of 129 amino acids. Sequence analysis revealed neither significant similarity of GMCHI to known proteins, nor any conserved domains found. Soybean seed imbibed at 4 degrees C dramatically enhanced transcript level of GMCHI after 1 h, and reached a maximum at 18 h, while the expression was only detected in the embryonic axis. GMCHI expression was strongly induced by treatment with ABA and PEG, but weakly by 250 mM NaCl which suggests that GMCHI is probably regulated by ABA-dependent signal transduction pathway during cold acclimation. Overexpression of GMCHI in Arabidopsis under the control of CaMV35S promoter enhanced the tolerance to cold, drought and NaCl stresses. Therefore, GMCHI may play an important role in the adaptation of chilling-resistant soybean seed to chilling imbibition.
