Stress Inducible Overexpression of AtHDG11 Leads to Improved Drought and Salt Stress Tolerance in Peanut (Arachis hypogaea L.).

Jayanna N Banavath,Chandra O R Puli,Sravani Konduru,Chandra S Akila,Sudhakar Podha,Varakumar Pandit,Krishna K Guduru,Thammineni Chakradhar

doi:10.3389/fchem.2018.00034

Abstract

Peanut is an important oilseed and food legume cultivated as a rain-fed crop in semi-arid tropics. Drought and high salinity are the major abiotic stresses limiting the peanut productivity in this region. Development of drought and salt tolerant peanut varieties with improved yield potential using biotechnological approach is highly desirable to improve the peanut productivity in marginal geographies. As abiotic stress tolerance and yield represent complex traits, engineering of regulatory genes to produce abiotic stress-resilient transgenic crops appears to be a viable approach. In the present study, we developed transgenic peanut plants expressing an Arabidopsis homeodomain-leucine zipper transcription factor (AtHDG11) under stress inducible rd29A promoter. A stress-inducible expression of AtHDG11 in three independent homozygous transgenic peanut lines resulted in improved drought and salt tolerance through up-regulation of known stress responsive genes (LEA, HSP70, Cu/Zn SOD, APX, P5CS, NCED1, RRS5, ERF1, NAC4, MIPS, Aquaporin, TIP, ELIP) in the stress gene network, antioxidative enzymes, free proline along with improved water use efficiency traits such as longer root system, reduced stomatal density, higher chlorophyll content, increased specific leaf area, improved photosynthetic rates, and increased intrinsic instantaneous WUE. Transgenic peanut plants displayed high yield compared to non-transgenic plants under both drought and salt stress conditions. Holistically, our study demonstrates the potentiality of stress-induced expression of AtHDG11 to improve the drought, salt tolerance in peanut.

Highlights

Peanut or groundnut (Arachis hypogaea L.) is globally important legume crop belonging to the Fabaceae family
Five hundred cotyledonary node (CNN) explants in five batches were co-cultivated with Agrobacterium strain (EHA105) harboring AtHDG11 (Supplementary Figure 1A) by exposing the proximal cut ends of explants in the bacterial suspension
Soil moisture stress at various growth stages of peanut often limit the quality of production in semi-arid tropics (SAT) regions

Summary

Introduction

Peanut or groundnut (Arachis hypogaea L.) is globally important legume crop belonging to the Fabaceae family. Drought and Salt Tolerance Transgenic Peanut (Mace et al, 2006; Cuc et al, 2008). Such unfavorable environmental conditions severely affect the plant growth and productivity. Drought and salt stress are the serious constraints affecting both productivity and quality of peanut in SAT regions (Wright and Nageswara Rao, 1994; Reddy and Anbumozhi, 2003; Krishna et al, 2015). Soil salinity in the SAT regions reduces the plants ability to uptake minerals that inhibits growth and development of peanut, which is known as “saline induced water deficit effect” or “osmotic effect” (Singh and Abrol, 1985; Nautiyal et al, 1989; Singh et al, 1989; Janila et al, 1999)

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Conclusion