Identification of drought‐responsive genes by cDNA‐amplified fragment length polymorphism in maize

Abstract

AbstractThe cDNA‐AFLP (amplified fragment length polymorphism) technique was performed to detect transcript‐derived fragments related to drought tolerance in maize inbred lines X178 and B73 to identify and understand drought‐responsive genes at the transcriptional level. By comparing the sequences of fragments differentially expressed between these lines under water‐stressed and well‐watered conditions, 72 drought‐responsive unique expressed sequence tags (ESTs) were identified with 41 primer combinations targeting PstI/MseI restriction sites. Most of the fragments isolated in these experiments were found to be associated with genes responsive to abiotic or biotic stresses. Subsequently, a putative R1‐type MYB transcription factor gene corresponding to ZmMYB‐R1 on bin 9.03 was obtained by in silico cloning by homology to EST sequence P36M87‐366, which matched one of the AFLPs identified in this study. The 1881 bp sequence encodes a protein of 626 amino acids that contains a single conserved MYB‐like DNA‐binding domain. Expression of green fluorescence protein fusions showed that ZmMYB‐R1 was localised in the cell nucleus. Quantitative real‐time polymerase chain reaction revealed that ZmMYB‐R1 was induced by drought, high salt, heat, cold and exogenous ABA in maize. The expression of ZmMYB‐R1 initially reaches its highest levels in leaves, then is subsequently also detected in stems and roots. This work revealed genes potentially responsible for drought tolerance in maize, and a new gene, ZmMYB‐R1, was shown to be associated with water stress.