TY - JOUR

T1 - Enhanced root growth of the brb (bald root barley) mutant in drying soil allows similar shoot physiological responses to soil water deficit as wild-type plants

AU - Dodd, Ian C.

AU - Diatloff, Eugene

PY - 2016/1/4

Y1 - 2016/1/4

N2 - The genetics, molecular biology and nutrient uptake of plant root hair mutants have been studied in detail, but their physiological responses to soil drying have not. Thus, the root hairless brb (bald root barley) barley (Hordeum vulgare L.) mutant and its wild type (WT) were grown in drying soil. Well-watered, pre-tillering plants showed no genotypic differences in daily transpiration and leaf elongation rate, and the ratio of day to night leaf elongation (D/N, a sensitive indicator of water stress). After withholding water for 25 days, root hydraulic conductivity and xylem ABA concentration were similar between genotypes, but WT plants had more tillers and D/N was more than halved in brb. To avoid possible developmental and nutritional differences confounding responses to water deficit, pre-tillering plants were allowed to dry soils of high and low phosphorus (P) status. Although leaf area, leaf water potential and shoot fresh weight (FW) were similar in the two genotypes, root FW of brb was greater by 44 and 18% in a high and low P soil respectively. This adaptive response allowed brb to maintain similar shoot growth and transpiration as WT plants, despite decreased effective root surface area in the absence of root hairs.

AB - The genetics, molecular biology and nutrient uptake of plant root hair mutants have been studied in detail, but their physiological responses to soil drying have not. Thus, the root hairless brb (bald root barley) barley (Hordeum vulgare L.) mutant and its wild type (WT) were grown in drying soil. Well-watered, pre-tillering plants showed no genotypic differences in daily transpiration and leaf elongation rate, and the ratio of day to night leaf elongation (D/N, a sensitive indicator of water stress). After withholding water for 25 days, root hydraulic conductivity and xylem ABA concentration were similar between genotypes, but WT plants had more tillers and D/N was more than halved in brb. To avoid possible developmental and nutritional differences confounding responses to water deficit, pre-tillering plants were allowed to dry soils of high and low phosphorus (P) status. Although leaf area, leaf water potential and shoot fresh weight (FW) were similar in the two genotypes, root FW of brb was greater by 44 and 18% in a high and low P soil respectively. This adaptive response allowed brb to maintain similar shoot growth and transpiration as WT plants, despite decreased effective root surface area in the absence of root hairs.

KW - leaf elongation

KW - rhizosphere

KW - soil drying

KW - water uptake

KW - ORYZA-SATIVA L.

KW - ABSCISIC-ACID

KW - HAIR DEVELOPMENT

KW - HYDRAULIC CONDUCTIVITY

KW - HORDEUM-VULGARE

KW - LEAF EXPANSION

KW - STRESS

KW - ACCUMULATION

KW - ACQUISITION

KW - ELONGATION

U2 - 10.1071/FP15303

DO - 10.1071/FP15303

M3 - Journal article

VL - 43

SP - 199

EP - 206

JO - Functional Plant Biology

JF - Functional Plant Biology

SN - 1445-4408

IS - 2

ER -