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Drought stress condition increases root to shoot ratio via alteration of carbohydrate partitioning and enzymatic activity in rice seedlings

Author:
Xu, Wei, Cui, Kehui, Xu, Aihui, Nie, Lixiao, Huang, Jianliang, Peng, Shaobing
Source:
Acta physiologiae plantarum 2015 v.37 no.2 pp. 9
ISSN:
0137-5881
Subject:
beta-fructofuranosidase, correlation, cultivars, drought, drought tolerance, enzyme activity, hydroponics, leaves, polyethylene, rice, root shoot ratio, roots, seedlings, starch, stems, sucrose, sucrose synthase, sucrose-phosphate synthase, water stress
Abstract:
To understand the underlying mechanism for plasticity in root to shoot ratio (R/S) in response to drought stress, two rice cultivars, Zhenshan97 (drought susceptible) and IRAT109 (drought resistant), were grown hydroponically, and R/S, carbohydrate concentration and partitioning, and activities of enzymes for sucrose conversion in seedlings exposed to drought stress condition (DS) imposed by polyethylene glycol ₆₀₀₀ were investigated. The R/S significantly increased under DS in comparison with that under well-watered condition. The proportion of dry matter and soluble sugar of roots markedly increased under DS. The R/S was negatively correlated with proportion of soluble sugar in stems, and positively with the proportions of soluble sugar and starch in roots. Drought stress condition significantly increased leaf sucrose-phosphate synthase (EC 2.4.1.14) activity and root acid and neutral/alkaline invertase (EC 3.2.1.26) activity. The R/S was positively correlated with leaf sucrose-phosphate synthase and root acid invertase activity, and negatively with leaf sucrose synthase activity in the cleavage direction. Our results indicate that the increase in R/S in response to DS is closely associated with the higher proportion of dry matter and soluble sugar in roots, and this occurs via an increase in leaf sucrose-phosphate synthase and root invertase activity, and thus more sucrose is available for transport from leaves to roots.
Agid:
1201940