International Journal of Integrative Biology BBB10 Special issue, 2010, Vol. 9, No. 3, 113 ©IJIB, All rights reserved Plasmids of endophytic bacteria INTRODUCTION The capability of colonizing internal host tissue has made endophytic bacteria valuable for agriculture as a tool to improve crop performance. Plant growth and plant crop yield can be increased by inserting genes of interest in the plant. This can be accomplished with the help of vectors. So far the approaches of transgenic plant development were by using techniques like microinjection, protoplast fusion, gene gun and transformation by Agrobacterium sp. and using either phage or bacterial vectors. Salles (Salles et al., 2000) has reported the use of endophytic bacteria as vectors to express a cry gene from Bacillus thuringiensis in sugarcane. In another report, the tumorous outgrowths in Olive plants were found to be induced by the transfer of a 52 Kb plasmid pIAA1 by Pseudomonas savastanoi and its other pathovars (Penyalver et al., 2002). The horizontal gene transfer has been studied in case of degradative plasmids pTOM-Bu61, pNAH7 and pWWO of endophytic Pseudomonas sp. These are naturally transferred to number of different endophytes, inplanta. Thus, the natural endophytes also get equipped with the plasmids and long term establishment of inoculant strain is not needed (Taghavi et al., 2005; Ryan et al., 2007; Ryan et al., 2008). The benefits of using endophytic bacteria being easy colonisation of internal plant tissues where chemicals and other biological agents are not effective, and low survival in soil decreases the possibility of gene transfer to other microorganisms. However, use of selective markers and the plasmid harboring it as vector is much more viable solution than the whole cells for reasons of incomplete expression pattern or sheer incompatibility. With the use of plasmids as vector, in a suitable carrier such as Agrobacterium sp., the genes of interest can be successfully expressed. Plasmids are useful for wide range of molecular, genetic, genomic and proteomic approaches. They help to introduce genes and to compliment mutations. Plasmids play a role in horizontal gene transfer as well as in manipulating expression levels of different genes. Plasmids can serve as vehicles for transposons and integrons. Thus, through plasmid conjugation bacteria are exposed to a wide array of genes from mobile gene pool. * Corresponding author: Sushama R. Chaphalkar, Ph.D. Vidya Pratishthan’s School of Biotechnology, Vidyanagari, Baramati. Maharashtra, India. 413133 Email: director.vsbt@gmail.com Regular International Journal of Integrative Biology A journal for biology beyond borders ISSN 0973-8363 Plasmids of endophytic bacteria as vectors for transformation in plants Chanda V Berde, Priya P Bhosale, Sushama R Chaphalkar * Vidya Pratishthan’s School of Biotechnology, Baramati, MS, India Submitted: 30 Mar. 2010; Accepted: 8 Apr. 2010 Abstract The endophytic microorganisms in general have a rich potential as producers of novel bioactive compounds, as nitrogen fixers, IAA producers, plant toxicity reducers, etc. Endophytic bacteria can also be used as vectors for transferring genes of interest to plants. These plasmid bearers have the advantage of colonizing the plant and rhizosphere with ease. In the present work, plasmids of endophytic bacteria were used as vectors instead of whole organism, for genetic studies. The advantage being transfer of plasmid encoded plant beneficial properties along with genes of interest to the plant. The present study encompasses screening of 27 medicinal plants for the endophytic colonization, in the plants. Amongst the collection of about 50 distinct endophytes, it was observed that most of these endophytes (> 50%) harbour plasmids. A bacterial isolate from Anthacephalus kadamba, Ec 14 has proven to be an ideal candidate for gene transformation in plants. It produces antibacterial proteinaceous compound that is active against plant pathogens. Antibiotic sensitivity and antibiotic peptide production were found to be plasmid born, confirmed by plasmid curing. Plasmid has restriction sites for the enzymes EcoRI, EcoRV, HindIII, SalI and BamHI. Keywords: Endophytes, bacteria, plasmids, vectors, antibacterial peptides.