Abstract

Abstract: The macrozone of northern Chile represents a geographical area of the country where agricultural development is significantly constrained by the salinity and boron conditions of the soils and irrigation water, which are imposed by the Atacama Desert. The maize variety Capia Blanco, classified as “ancestral/native”, demonstrate tolerance to excess boron in irrigation water and is a source of maize cobs (choclos) in the region. This study determined the expression of genes encoding putative BOR1 and BOR2 proteins under conditions of high boron (B) concentrations in two native maize varieties, Capia Blanco and Diente de Caballo. Boron content was determined and the gene expression profiles of the boron transporters (ZmBOR1 and ZmBOR2) in leaf tissue were determined by qRT?PCR analysis. The results show that Capia Blanco has less boron in its leaves than sensitive maize when exposed to 60 mg L?1 boron for 29 days. This is because it does not have the ZmBOR2 gene, which is expressed under high boron stress. The native variety Capia Blanco develops an avoidance strategy during the first 0.125 days (3 h) at the leaf level when exposed to excess boron, which allows it to survive high doses of boron in irrigation water. We propose that this maize native cultivar is tolerant to excess B, most likely through genetic regulation (mainly negative) of B transport in plant organs. © The Author(s) under exclusive licence to Sociedad Chilena de la Ciencia del Suelo 2025.