Characterization of two F-BOX proteins involved in maize drought tolerance

BOUZO, C; LOBAIS, C; DOTTO, M; MISKEVISH, F; BLANCO, N

Congreso; XXXIII Reunión Argentina de Fisiología Vegetal; 2021

One of the major threats to agricultural production is water limitation, which often leads to drought stress and results in compromised growth, development and yield of crop species. In this context, drought tolerance has been intensively studied in search for potential targets for molecular approaches to crop improvement. However, drought adaptive traits are complex and our understanding of the physiological and genetic basis of drought tolerance is still incomplete. It has been shown that Arabidopsis plants overexpressing miR394, a 20-nt-long regulatory microRNA and lcr plants harboring mutations in its regulated gene, LEAF CURLING RESPONSIVENESS, are highly tolerant to severe drought conditions. Therefore, we explored this aspect of the miR394-LCR regulatory module in maize, a species of significant agronomical interest in our country and high value to world-wide crop production. We characterized the miR394 pathway in maize and identified two genetic loci producing an evolutionarily conserved mature zma-miR394, which targets two transcripts coding for F-BOX proteins, named hereby ZmLCR1 and ZmLCR2. Analysis of growth and development of single and double zmlcr mutant plants indicate these mutations do not affect plant fitness negatively when they grow in normal watering conditions, but mutants showed better survival than WT under drought stress conditions. This increased drought tolerance is based on a higher photosynthetic activity in the mutants, resulting in a more efficient water use under limiting conditions. Our results indicate that the miR394-ZmLCR module is involved in drought stress tolerance in maize and the ZmLCR genes are remarkable candidates for maize crop improvement.