REGULATION OF CARBOHYDRATE METABOLISM IN CHICKPEA (Cicer arietinum L.) UNDER DROUGHT STRESS.
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Date
2019-09-30
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CSK HPKV, Palampur
Abstract
Chickpea (Cicer arietinum L.), a cool season annual self-pollinated diploid (2n=2x=16) legume crop with genome size of ∼740 Mbp, is believed to be originated in South-East Turkey and contributes maximum production among the pulses under Mediterranean type environment. Although, chickpea is known for its better drought tolerance than other legumes, terminal drought hinders its production severely even sometimes lead to total crop failures. With the aim to understand regulation of carbohydrate metabolism in chickpea under drought stress, changes in amount of carbohydrate contents, expression of carbohydrate metabolism genes and relative water content (RWC) in leaves of both drought susceptible (ICC 3776) and drought tolerant (ICC 8950) genotypes were studied. Seven genes (ADP-glucose pyrophosphorylase, Phospho-glucan/water dikinase, Iso-Amylase3, Starch synthase4, Beta-amylase1, Beta-amylase3, and Granule-bound starch synthase2) involved in starch metabolism and three genes (Sucrose-phosphate synthase2 like, UDP-glucose pyrophosphorylase, and Cell wall invertase3LX2) involved in sucrose metabolism were studied. Decreased RWC in leaves of the susceptible genotype compared to the tolerant one indicated susceptibility of ICC 3776 to drought. Amounts of total sugars, reducing sugars, non-reducing sugars and sucrose were significantly increased in both the genotypes under induced drought, but in each case, increment was higher in the susceptible genotype. Starch content increased in the susceptible genotype whereas it remained static in the tolerant one. Downregulation of major starch degrading enzyme Beta-amylase3 and simultaneous upregulation of starch synthesizing enzyme starch synthase4 contributed in starch increment despite the upregulation of beta-amylase1 and iso-Aamylase3 in the susceptible genotype. In ICC 8950, starch synthesizing as well as starch degradation enzymes with the exception of Phospho glucan/water dikinase downregulated. Increased accumulation of sucrose content in susceptible genotype compared to tolerant one under induced drought can be attributed to lower expression of Cell wall invertase3LX2 in the susceptible genotype. The study provided insights into sugar metabolism under drought tolerance and drought susceptibility.
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