Engineering resistance in brinjal against nematode (Meloidogyne incognita) using cry1Ab gene from Bacillus thuringiensis Berliner Phan Dinh Phap 1,2 , Hoang Thi Lan Xuan 1 , D. Sudhakar 2 and P. Balasubramanian 2 1 School of Biotechnology, International University-National University Ho Chi Minh City, Vietnam 2 Centre for Plant Molecular Biology, Tamil Nadu Agricultural University, India Abstract— Transgenic brinjal plants (Solanum melongena cv. Co2) expressing cryIAb gene from Bacillus thuringiensis Berliner (Bt) were evolved by Agrobacterium-mediated transformation system. In the present study, 7 T 0 lines (P- Co2IAb-5, P-Co2IAb-9, P-Co2IAb-10, P-Co2IAb-12, P- Co2IAb-16, P-Co2IAb-17 and P-Co2IAb-22) harboring cryIAb gene were obtained. PCR and Southern blotting analyses proved the presence and integration of cryIAb in these lines. A polyclonal rabbit anti-CryIAb antiserum detected the expression of a 65 kDa CryIAb polypeptide in all these lines. Expression of CryIAb protein in those transgenic lines was also confirmed by lateral flow sticks (CryIAb) assay. Molecular analyses in T 1 progenies harboring cryIAb gene proved the presence and expression of the transgene of interest. The chi-square ( 2 ) tests revealed a 3:1 segregation ratio for cryIAb gene in the lines viz., P-Co2IAb-5 and P- Co2IAb-9, indicating that the transgene was integrated at a single locus. The transgenic lines thus obtained in this study were used to investigate the potential of the CryIAb protein in controlling the root knot nematode, Meloidogyne incognita. Bioassay for root knot nematode resistance in T 1 plants expressing CryIAb showed that there was a significant decrease in number of galls and eggmasses in cryIAb-transgenic lines (P-Co2IAb-5 and P- Co2IAb-9) as compared to control. In addition, there was a significant decrease in the number of eggs per eggmass on those transgenic lines tested than the non-transgenic controls. Thus, transgenic Bt-brinjal plants could also form a part of an integrated nematode management program. Keywords— Transgenic brinjal, Bacillus thuringiensis, cryIAb, Agrobacterium transformation, Meloidogyne incognita. I. INTRODUCTION Brinjal (Solanum melongena Linnaeus) is an economically important vegetable crop grown in many countries in Asia, Europe and North America. It forms an important component in the diet of the people, especially in the Indian subcontinent whose diet is predominantly vegetarian in nature. Brinjal is high in nutritive value in vitamins A and C and also known as eggplant. Brinjal is susceptible to a host of insect pests and diseases, particularly shoot and fruit borer (SFB; Leucinodes orbonalis Guenee), Colorado potato beetle (CPB; Leptinotarsa decemlineata Say), aphid (Aphis gossypii Glover), Fusarium wilt (F. oxysporum f.sp. melongenae), nematodes (Meloidogyne spp.), etc., which reduce the marketable yield in a large measure. Resistance genes have been found in different wild Solanum species. However, the introduction of these genes via intergeneric crossing or asymmetric protoplast fusion is often limited, due to sterility problems [1]. Genetic transformation is a promising strategy for brinjal improvement because it overcomes the incompatibility barriers among crop species by allowing the introduction of foreign genes into plants. Bacillus thuringiensis, a gram-positive bacterium is commonly found in soil, plant surfaces, insect cadavers and in grain storage dusts [2]. Different strains of B. thuringiensis produce one or more proteins, grouped as -endotoxins, which accumulate during sporulation to form refractile crystal bodies. The -endotoxins earlier were classified into four types, based on insect specificity and sequence homology, into Lepidopteran-specific (cryI), Lepidopteran and Dipteran-specific (cryII), Coleopteran- specific (cryIII) and Dipteran-specific (cryIV) [3]. The system was further extended to include cryV that encode for proteins effective against Lepidopteran and Coleopteran larvae. Some B. thuringiensis strains have also been reported to be active against mites, nematodes, flatworms, protozoa [4, 5, 6] and aphids [7]. Guri and Sink [8] were the first to report Agrobacterium- mediated transformation of brinjal, quickly followed by others [9, 10]. Attempts were first made to introduce a native version of Coleopteran-specific gene cryIIIB of Bacillus thuringiensis into brinjal conferring resistance to CPB, but their expression was too low for successful insect control [11]. A modified cryIIIA gene was developed and successfully introduced into brinjal, in which were found resistant to neonate larvae and adult CPB [12]. A synthetic cryIAb gene was introduced into a long-fruited (Pusa purple long) variety of brinjal. Fruits of one of the transformants were totally protected from SFB larval damage [9]. Resistance to the root knot nematode (M. incognita) has been engineered by inserting the Mi-1 gene from wild tomato (Lycopersicon peruvianum) [10]. Proceedings of the 3rd International Conference on the Development of BME in Vietnam, 11-14th Jan 2010 277