Overexpression of a chitinase gene in transgenic peanut confers enhanced resistance to major soil borne and foliar funga
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IGINAL ARTICLE
Overexpression of a chitinase gene in transgenic peanut confers enhanced resistance to major soil borne and foliar fungal pathogens Kalyani Prasad & Pooja Bhatnagar-Mathur & Farid Waliyar & Kiran K. Sharma
Received: 1 May 2012 / Accepted: 10 September 2012 / Published online: 23 September 2012 # Society for Plant Biochemistry and Biotechnology 2012
Abstract A chitinase gene from rice (Rchit) was introduced into three varieties of peanut through Agrobacterium-mediated genetic transformation resulting in 30 transgenic events harboring the Rchit gene. Stable integration and expression of the transgenes were confirmed using PCR, RT-PCR and Southern blot analysis. Progeny derived from selfing of the primary transgenic events revealed a Mendelian inheritance pattern (3:1) for the transgenes. The chitinase activity in the leaves of the transgenic events was 2 to 14-fold greater than that in the non-transformed control plants. Seeds of most transgenic events showed 0–10 % A. flavus infection during in vitro seed inoculation bioassays. Transgenic peanut plants evaluated for resistance against late leaf spot (LLS) and rust using detached leaf assays showed longer incubation, latent period and lower infection frequencies when compared to their non-transformed counterparts. A significant negative correlation existed between the chitinase activity and the frequency of infection to the three tested pathogens. Three progenies from two transgenic events displayed significantly higher disease resistance for LLS, rust and A. flavus infection and are being advanced for further evaluations under confined field conditions to confirm as sources to develop peanut varieties with enhanced resistance to these fungal pathogens. Keywords Arachis hypogaea . Aspergillus flavus . Groundnut . Rice chitinase . Transgenic . Peanut . Late leaf spot disease . Rust K. Prasad : P. Bhatnagar-Mathur : K. K. Sharma (*) Genetic Transformation Laboratory, International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru AP 502 324, India e-mail: [email protected] F. Waliyar International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), BP 12404, Niamey, Niger
Abbreviations LLS Late leaf spot SAT Semi arid tropics SEM Shoot elongation media
Introduction Peanut or groundnut (Arachis hypogaea L.) is an agronomically and economically important oilseed crop grown extensively throughout the tropical and sub-tropical regions of the world. Fungal diseases such as late leaf spot (LLS) caused by Phaeoisariopsis personata (Berk. and Curt.) Van. Arx, and rust caused by Puccinia arachidis Speg. are the most important foliar diseases, besides Aspergillus flavus contamination that affect the peanut production and quality (Waliyar et al. 2000). Foliar diseases damage the plant by reducing the green leaf area available for photosynthesis and by stimulating leaflet abscission leading to extensive defoliation which results in lower seed quality, reduced seed size and oil content besides affecting the haulm production and qu
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