INTRODUCTION Potato is a significant, widely cultivated commercial cash crop around the world. In Pakistan, it is cultivated on an area of 178.22 thousand hectares with production of 4000.3 thousand tones (FAOSTAT, 2016) annually. It is a vegetatively propagated crop, therefore diseases can be easily transmitted from one infectious generation to other, rendering this crop prone to several, viral, bacterial and fungal diseases. Among the fungal diseases the most commonly are the late blight, early blight, Fusarium wilt, stem cankers and verticillium wilt. Economic loss due to these diseases, sometime occurs as high as 75% (Khalid et al., 2000). Potato is a tetraploid and heterozygous in nature due to which breeding for disease resistance is difficult by conventional means. Therefore, it is genuinely needed that the disease resistant potato cultivars be produced by other advance tools such as genetic manipulation. Foreign gene incorporation into crop plants through different transformation techniques as particle bombardment and agrobacterium methods have made easy for desired agronomic characteristics and resistance against pathogens (Altpeter et al., 2005; Tzfira and Citovsky 2006). Chitinases are pathogen related proteins, induced during fungal infection and found in wide variety of plants (Chai et al., 2002; Singh et al., 2015). Chitinase is considered as hydrolytic enzyme which degrades the chitin cell wall of majority of filamentous fungi. It hydrolyzes the chitin to N- acetyl glucosamine oligomers by cleaving β-1, 4 bonds. Many researchers have reported that transformation of chitinase genes in crops, may leads to resistance against different fungal pathogens. Nishizawa et al. (1999) reported higher level of resistance against rice blast pathogen Magnaporthe grisea by incorporation of class I rice chitinase gene described as rice chitinase cDNA clone (RCC2). While, Tabei et al. (1998) and Kishimoto et al. (2002) were successful to induce resistance in cucumber plants by incorporation of RCC2 genes against gray mold (Botrytis cinerea). Maximova et al. (2005) exploited antifungal activity of chitinase gene in transgenic Theobroma cacao containing cacao class I chitinase which enhanced the resistance against Colletotrichum gloeosporioides fungus. Kova et al. (2013) expressed rice chitinase gene in banana leading to resistance Pak. J. Agri. Sci., Vol. 56(1), 7-13; 2019 ISSN (Print) 0552-9034, ISSN (Online) 2076-0906 DOI: 10.21162/PAKJAS/19.8154 http://www.pakjas.com.pk INTRODUCTION OF RICE CHITINASE GENE IN POTATO BY AGROBACTERIUM-MEDIATED TRANSFORMATION Iqbal Hussain 1 , Hamid Rashid 1 , Aish Muhammad 1 , Kazim Ali 1 , Rehana Asghar 2 , S.M. Saqlan Naqvi 3 , Nadia Faqir 1 and Muhammad Zeeshan Hyder 4, * 1 National Institute for Genomics and Advanced Biotechnology, National Agricultural Research Center, Islamabad, Pakistan; 2 Department of Biotechnology, Mirpur University of Science and Technology, Mirpur, Pakistan; 3 Department of Biochemistry, Pir Mehr Ali Shah, Arid Agriculture University Rawalpindi, Pakistan; 4 Department of Biosciences, COMSATS University Islamabad, Park Road, Islamabad Pakistan. * Corresponding author’s e-mail: zeeshan_hyder@comsats.edu.pk Potato is an important food crop of the world. Different viral, bacterial and fungal pathogens cause heavy economic losses of this crop every year. Potato has complex genetic makeup due to which induction of disease resistance through conventional breeding is difficult. Genetic manipulation through different transformation techniques is more precise and successful tool. In the present study different factors were investigated, which have an influence on potato transformation. The optimal dose of cefotaxime was found 500 mg/l which did not affected the growth of the potato tissues. The explants treated with Agrobacterium in the presence of acetosyringone resulted in higher frequency of transformation as compared to the explant without it. Two minutes time for co infection was found appropriate for optimum transformation efficiency. The two days co- cultivation period along with 7 days preselection was found suitable for potato transformation. The putative tranformants regenerated on MS medium supplemented with 20 mg/L hygromycine and 500 mg/L cefotaxime, from nodal explants while the non-transformed tissue turned brown and gradually died after two or three sub culturing on the selection media containing selective antibiotic hygromycin. The shoots obtained on selection media shifted on root induction media supplemented with similar concentrations of hygromycin and cefotaxime, resulted complete plantlet formation after 10 days. It was observed that all the hygromycin positive plants also exhibited positive bands of desired size of 823 bp for chitinase gene, suggesting co- transformation of both genes in transformed plants. Keywords: Solanum tuberosum, chitin, hydrolytic enzyme, fungal pathogens.