Genetic engineering for peanut improvement: current status and prospects

Peanut is an important source of edible oil, dietary minerals, and vitamins, and proteins. Environmental stresses like biotic and abiotic factors are main constraints for peanut production and productivity. Generation of resistant varieties against these stresses can lead to quantum leap in the crop productivity. Potential biotechnology approaches through engineering and expression of novel genes can improve stress tolerance/resistance mechanisms that ultimately lead to crop adaptation and yield enhancement. There are several genetic engineering techniques are adopted, among them Agrobacterium mediated and biolistic methods are widely employed for transforming peanut varieties. Expression of abiotic stress related genes or transcription factors like DREB, PDH45, NAC, mtlD, NHX etc. in different peanut varieties resulted in enhanced tolerance to drought, salinity, temperature extremes and osmotic adjustments. In addition, expression of transgene could regulate the biochemical pathways which lead to scavenge free radicals, lipid peroxidation, increase photosynthetic efficiency, water use efficiency and transpiration rate. To address the biotic stresses, genes like glucanase, chitinase, chloroperoxidase, coat proteins, crystal proteins, and pathogen related genes have been expressed in peanut which exhibited enhanced resistance towards different fungal, bacterial pathogens and pests. Interestingly, plant based edible vaccines and therapeutic antibodies are produced in plants through the expression of urease B and oleosin to combat chronic infections. Allergy is a prime concern in peanut that is to be inhibited through RNA interference mechanisms. We review here factors influencing the transformation, recent progress in peanut transgenic research, development and future perspectives.