SEQUENCE COMPARISON OF MUTE PROMOTERS BETWEEN TWO WHEAT CULTIVARS REVEALED BOTH CONSERVATIVE AND DIVERGED REGIONS

Abstract

Modulation of stomatal biogenesis is one of the means to consider for improving crops' water use efficiency without losing productivity. Transcription factor MUTE is among the critical regulators of stomata biogenesis, particularly of the guard mother cell division. In the current study, we investigated promoter regions of three homoeologous MUTE genes–MUTE-A1, MUTE-B1, and MUTE-D1 from two bread wheat cultivars of different geographic origins. Based on the available sequence of the Chinese Spring genome, MUTE promoters were isolated and sequenced from the Ukrainian cultivar Natalka. Promoter regions of more than 1600 bp upstream of the predicted start codons were cloned as PCR-amplified fragments and analyzed by sequencing. The sequence alignments revealed significant subgenome and cross-cultivar heterogeneity of the analyzed promoters. The analysis showed numerous single nucleotide polymorphisms and large deletions in every Natalka sequence compared with Chinese Spring: 276-bp deletion in MUTE-A1, 205-bp in MUTE-B1, 1291-bp in MUTE-D1. These changes affected a range of cis-regulatory elements (light- and stress-responsive elements, as well as tissue-specific elements) within the investigated DNA sequences. The study sheds new light on the regulatory variation of one of the critical factors in stomata biogenesis, widening our understanding of wheat genome plasticity with potential implications for improving the crop's performance under restricted water conditions.