Better root:shoot ratio conferred enhanced harvest index in transgenic groundnut overexpressing the rd29A:DREB1A gene under intermittent drought stress in an outdoor lysimetric dry-down trial uri icon

abstract

  • An outdoor confined trial was conducted during thepostrainy season of 2009 for physiological evaluation ofinduced drought tolerance in transgenic plants ofgroundnut variety JL 24 overexpressing a transcriptionfactor, DREB1A driven by the stress-inducible promoterof the rd29A gene, both from Arabidopsis thaliana.Lysimetric system was used for growing the plants, whereintermittent drought stress was imposed at mid-floweringand peak pod-filling stages of the crop, by subjectingplants to a cycle of drying and re-watering. The lysimetricsystem facilitated complete recovery of roots, thereby,facilitating studies on variations in the root:shoot ratioinduced across the genotypes under controlled wellwatered(WW) and imposed drought stress (DS)conditions. Under DS the root:shoot ratio showed asignificant (P <0.005) positive correlation with pod yieldand harvest index (HI), reflecting clearly the betterperformance of two transgenic events GNRD11 andGNRD33 than the untransformed variety JL 24. Thetransgenic event GNRD11, in particular, showedenhanced HI along with significantly higher (P <0.05)seed yield that was 22% and 25% higher than JL 24 andthe elite breeding groundnut cultivar ICGV 86031,respectively. Better HI in these transgenic events, whencompared to the untransformed control, was mainly dueto the effective partitioning of the accumulated biomass,more towards roots and pods while relatively lesstowards shoot biomass, leading to higher root:shoot ratioand better yield, also suggesting better water useefficiency in the former compared to the latter

publication date

  • 2012