Differential response of root morphology to potassium deficient stress among rice genotypes varying in potassium efficiency

Abstract

Disparity in the root morphology of six rice (Oryza sativa L.) genotypes varying in potassium (K) efficiency was studied with three K levels: 5 mg/L (low), 10 mg/L (moderate) and 40 mg/L (adequate) in hydroponic culture. Morphological parameters included root length, surface area, volume and count of lateral roots, as well as fine (diameter<0.2 mm) and thick (diameter>0.2 mm) roots. The results indicate that the root growth of all genotypes was reduced under low K, but moderate K deficiency increased the root length of the efficient genotypes. At deficient and moderate K levels, all the efficient rice genotypes developed more fine roots (diameter<0.2 mm) than the inefficient ones. Both fine root count and root surface area were found to be the best parameters to portray K stress in rice. In accordance with the root morphology, higher K concentrations were noted in shoots of the efficient genotypes when grown at moderate and deficient K levels, indicating that root morphology parameters are involved in root uptake for K and in the translocation of K up to shoots. K deficiency affected not only the root morphology, but also the root ultra-structure. The roots of high-efficient genotypes had stronger tolerance to K deficient stress for root membrane damage, and could maintain the developed root architecture to adapt to the low K growth medium.

Potassium deficiency inhibits lateral root development in tobacco seedlings by changing auxin distribution

“…Since K + is the main osmotic cation in plant root cells, it is reasonable to surmise that K + deficiency would arrest root growth (Armengaud et al 2004;Dolan and Davies 2004;Shin and Schachtman 2004;Jung et al 2009;Zhang et al 2009;Jia et al 2008;Ma et al 2012;Gruber et al 2013;Kellermeier et al 2013). However, the mechanism by which K + deficiency inhibits root growth remains unclear, even in the model plant Arabidopsis.…”

“…Arabidopsis [Armengaud et al 2004;Shin and Schachtman 2004;Jung et al 2009], cotton [Zhang et al 2009] and rice [Jia et al 2008;Ma et al 2012]). In a classic study, Drew (1975) demonstrated increased lateral root (LR) growth in barley seedlings when K + was supplied only to selected portions of the root system.…”

Natural Variation as a Tool to Investigate Nutrient Use Efficiency in Plants

“…It has long been known that root architecture and plasticity reveal a response of plants to scarce nutrients, and natural variation exists for these traits in different species, related to potassium (Kellermeier et al 2013;Jia et al 2008), nitrogen (De Pessemier et al 2013, and phosphorus availability (Wang et al 2010). Natural variation for NUpE has been shown directly by measuring a specific mineral content in different genotypes, as Burns et al demonstrated for nitrate in different varieties of lettuce.…”

Effects of elevated CO2 levels on root morphological traits and Cd uptakes of two Lolium species under Cd stress

“…Cd is a non-essential element that negatively affects plant growth and development processes, such as respiration and photosynthesis (Greger and Ögren, 1991;Baryla et al, 2001;Vega et al, 2006), water and mineral uptakes (Singh and Tewari, 2003), cell division (Fojtová et al, 2002), and cellular redox homoeostasis (Romero-Puertas et al, 2004). From the viewpoint of water and nutrient uptakes, roots are of particular physiological importance (Bosac et al, 1995;Jia et al, 2008). Fine roots are usually more sensitive to exposure to either excessive metal concentrations (Arduini et al, 1995) or elevated levels of CO 2 (Day et al, 1996;Janssens et al, 1998;Phillips et al, 2006) when compared to coarse roots.…”