REVIEW ARTICLE Genetic engineering for salt and drought stress tolerance in peanut (Arachis hypogaea L.) P. B. Kavi Kishor 1 • K. Venkatesh 1 • P. Amareshwari 1 • P. Hima Kumari 1 • D. L. Punita 1 • S. Anil Kumar 1 • A. Roja Rani 1 • Naveen Puppala 2 Received: 3 August 2018 / Accepted: 19 November 2018 Ó Indian Society for Plant Physiology 2018 Abstract Peanut (Arachis hypogaea L.) is an important oil- yielding cash crop as well as an exportable agricultural com- modity. It is a rich source of proteins, fats, and plays a crucial role in oilseed economy of India and many other countries. Peanut frequently encounters water-deficit and soil salinity conditions that affect its growth and productivity. Traditional breeding methods were not successful in generating lines tol- erant to abiotic stress conditions. On the other hand, introduc- tion of genes through genetic engineering methods conferred tolerance against both biotic and abiotic stresses. In all, the transgenics that were developed so far, stable inheritance of transgenes was noticed. Transgenics displayed higher biomass, yield and better resistance to abiotic stresses when compared with wild-type plants inferring that this method has potential for improving the crop with desired traits. Genetically engineered stress tolerant peanut plants could provide an avenue to the restoration of farmlands lost due to severe drought or salinity conditions and highlight the potential of this technology for developing climate resilient crop. Keywords Arachis hypogaea Á Drought stress Á Genetic engineering Á Salt stress Introduction Peanut is an important crop grown throughout the world for its protein and oil content. About 830 million ha of the total land and 7.61 million ha of land in India is * salinity- affected (Martinez and Beltran 2005; Singh et al. 2007). Globally, the loss of peanut productivity due to drought stress alone is nearly 6 million tons (Bhatnagar-Mathur et al. 2014). Bosamia et al. (2015) pointed out that the area under drought and salinity is always on the rise in most of the groundnut cultivated areas of India as well as elsewhere either due to a deficit or high or erratic rainfall conditions. Few germplasm accessions of cultivated groundnut were identified as tolerant to salt stress conditions (Nautiyal et al. 2000). Such lines are being used directly in crop improvement programs globally (Mungala et al. 2008). Linkage drag and minor quantitative trait loci (QTLs) were identified in peanut for improved water use efficiency (Holbrook et al. 2011). But, polygenic nature of drought and salinity stresses restricts the conventional and molec- ular methods of breeding to develop tolerant varieties in peanut (Venkatesh et al. 2014). The constraints include the low genetic diversity, highly conserved genome, cross incompatibilities, limited range of polymorphism, genetic isolation of the tetraploid peanut from its wild diploid ancestors, difficulty in foreground and background selec- tions as pointed out by Varshney et al. (2005), Feng et al. (2012) and Janila et al. (2013). Conventional methods of plant breeding for developing drought tolerant varieties are laborious, time-consuming and yet the final yields are limited. Screening of peanut genotypes for abiotic stress tolerance and subsequent attempts to breed them for drought and salt stresses has been slow due to the rarity of alleles for these stresses (Bhatnagar-Mathur et al. 2007). Further, gene & Naveen Puppala npuppala@ad.nmsu.edu 1 Department of Genetics, Osmania University, Hyderabad 500 007, India 2 New Mexico State University, Agricultural Science Centre at Clovis, 2346 SR 288, Clovis, NM 88101, USA 123 Ind J Plant Physiol. https://doi.org/10.1007/s40502-018-0421-5