Near-isogenic wheat lines carrying altered function alleles of the Rht-1 genes exhibit differential responses to potassium deprivation

Abstract

Most of the elements involved in the integration of signals of low external K+-supply into a physiological response pathway remain essentially unknown. The aim of this work was to study the influence exerted by DELLA proteins, which are known to be key components for the control of growth, on plant responses during K+ deprivation in wheat (Triticum aestivum) by using two sets of near-isogenic lines (NILs) in the Maringa and April Bearded cultivars. After K+ shortage, the NILs of both cultivars containing the Rht-B1b,Rht-D1b alleles, which encode altered function DELLA proteins, displayed either a slight or no decrease in chlorophyll content, in contrast to the sharp decrease observed in the NILs having the wild type alleles (Rht-B1a,Rht-D1a). That difference was accompanied by a lower relative decrease of biomass accumulation only in the Maringa cultivar. In both cultivars, high chlorophyll retention was coupled with K+ starvation-induced differences in superoxide dismutase and ascorbate peroxidase activities, which were enhanced in K+-starved Rht-B1b,Rht-D1b NILs. In addition, Rht-B1b,Rht-D1b and Rht-B1a,Rht-D1a NILs markedly differed in the accumulation of the major cations Ca2+, Na+ and K+. These results suggest a major role of the Rht-1 genes in the control of physiological responses during K+ deprivation.