Regulated Expression of an Isopentenyltransferase Gene (IPT) in Peanut Significantly Improves Drought Tolerance and Increases Yield Under Field Conditions

Abstract

Isopentenyltransferase (IPT) is a critical enzyme in the cytokinin biosynthetic pathway. The expression of IPT under the control of a maturation- and stress-induced promoter was shown to delay stress-induced plant senescence that resulted in an enhanced drought tolerance in both monocot and dicot plants. This report extends the earlier findings in tobacco and rice to peanut (Arachis hypogaea L.), an important oil crop and protein source. Regulated expression of IPT in peanut significantly improved drought tolerance in both laboratory and field conditions. Transgenic peanut plants maintained higher photosynthetic rates, higher stomatal conductance and higher transpiration than wild-type control plants under reduced irrigation conditions. More importantly, transgenic peanut plants produced significantly higher yields than wild-type control plants in the field, indicating a great potential for the development of crops with improved performance and yield in water-limited areas of the world.

Conditional up-regulation of cytokinin status increases growth and survival of sugarcane in water-limited conditions

“…RAB25 and SAG32 transgenic plants and those that received external supply of CK displayed statistically significantly higher g s than wildtype plants after 36 days of water stress treatment. Similar results were observed in IPT upregulated transgenic peanut under water stress conditions (Qin et al, 2011) and tomato under salt stress conditions (Ghanem et al, 2011) and tobacco (Wang et al, 1997) in non-stressed condition.…”

“…Similar results were also reported in IPT transgenic cotton (Kuppu et al, 2013), peanut (Qin et al, 2011) and tobacco (Rivero et al, 2010) with reduced water supply.…”

“…In addition to exogenous manipulation, following the discovery of an isopentenyltransferase gene (IPT) from Agrobacterium tumefaciens and its role in cytokinin biosynthesis (Barry et al, 1984), efforts were made to express this gene to up-regulate the production of CK to improve growth under water stress conditions (Kuppu et al, 2013, Qin et al, 2011, Merewitz et al, 2011d, Rivero et al, 2010. The above findings point to potential applications of CK for improving or stabilising agricultural yields where crop growth is limited by water (Ha et al, 2012).…”

Stress-Induced Cytokinin Synthesis Increases Drought Tolerance through the Coordinated Regulation of Carbon and Nitrogen Assimilation in Rice

“…Elevated CK levels enhanced the survival of plants under water-stress conditions (Rivero et al, 2007). The overexpression of IPT under the control of SENESCENCE-ASSOCIATED RECEPTOR KINASE (SARK; a maturationand stress-induced promoter) improved the drought tolerance of both eudicots (Rivero et al, 2007;Qin et al, 2011) and monocots . After a water-stress episode during the reproductive stages (pre and post anthesis), transgenic P SARK ::IPT rice (Oryza sativa) plants displayed higher grain yield than the wild type .…”

“…Under drought stress, plant CK content decreases, and the reduction in CK increases the plant responses to increasing ABA (Davies and Zhang, 1991), inducing stomata closure and inhibiting photosynthesis (Rivero et al, 2010). Our previous results suggested that the stress-induced CK synthesis, driven by a stress-induced promoter, protected against the deleterious effects of water deficit on the photosynthetic apparatus, allowing higher photosynthetic rates and higher yields after water deficit in tobacco (Rivero et al, 2009) and cotton (Gossypium hirsutum; Kuppu et al, 2013) plants grown in the greenhouse and peanut (Arachis hypogaea) plants grown under field conditions (Qin et al, 2011).…”