Altered function Rht alleles contribute to antioxidant response during the acclimation of wheat plants to potassium deficiency

JORGE I. MORICONI; AGUSTINA BUET; MARCELA SIMONTACCHI; GUILLERMO E. SANTA MARÍA

San Pablo

Congreso; VII Meeting of the SFRBM South American Group; 2011

SFRBM South American Group

Potassium (K+) has proved to be an essential nutrient for plant growth and development. Understanding the mechanisms involved in the growth restriction that takes place under K+-limiting condition could help to find genotypes with improved K+ -use efficiency, which is a major objective of plant breeders. However, the way by which plants restrict their growth under K+ deprivation conditions is not well understood. In bread wheat (Triticum aestivum), DELLA proteins are encoded by the Rht-B and Rht-D genes: the allelic variants Rht-Ba /Rht-Da, determine a “normal” phenotype, while the presence of the altered functions Rht-B1b /Rht-D1b alleles reduce plant height. The aim of this study was to evaluatethe role of those different versions in the acclimation of plants to K+ deprivation. Experiments were conducted with two set of near isogenic lines (NILs) of Maringa and April Bearded cultivars. Rht-B1b/Rht-D1b plants of both cultivars displayed no senescent response, while chlorophyll content of Rht-B1a/Rht-D1a plants sharply declined, over a 16 day K+-deprivation period. While in Maringa this difference exerted a positive impact on plant growth, no differences in the relative biomass accumulation between Rht-B1b/Rht-D1b and Rht-B1a/Rht-D1a NILs were observed in April Bearded.  While no differential effect on protein carbonilation or lipid peroxidation was detected between NILs, the presence of Rht-B1b/Rht-D1b alleles –in both cultivars- induced a major change in the antioxidant response, particularly SOD activity, as well as changes in the ionic composition (K+, Na+, Ca2+) under K+-deprivation conditions. Our data indicate that the presence of altered function alleles influences the acclimation response of wheat plants to K+-deprivation at least in part through a modification of the antioxidant response.