Journal of Phytopathology. 2017;1–7. wileyonlinelibrary.com/journal/jph | 1 © 2017 Blackwell Verlag GmbH Received: 15 May 2017 | Accepted: 26 July 2017 DOI: 10.1111/jph.12615 ORIGINAL ARTICLE Phenylalanine ammonia-lyase gene induction with benzothiadiazole elevates defence against Lasiodiplodia theobromae in tea in India Shibu Das 1 | Prosenjit Chakraborty 1 | Parimal Mandal 2 | Dipanwita Saha 3 | Aniruddha Saha 1 1 Department of Botany, University of North Bengal, Siliguri, India 2 Department of Botany, Raiganj University, Raiganj, India 3 Department of Biotechnology, University of North Bengal, Siliguri, India Correspondence Aniruddha Saha, Department of Botany, University of North Bengal, Siliguri, India. Email: asahanbu@yahoo.co.in Funding information UGC Abstract Tea is widely used as an aromatic beverage cultivated in more than 35 countries from different continents. The global production of tea during the year 2015–2016 was 5,303 million kg where India stands 2nd contributing 23% of the world production. Diplodia disease is one of the most common diseases of tea in sub-Himalayan West Bengal, India. Phenylpropanoids act as a precursor of several secondary metabolites that are synthesized at the time of biotic and abiotic stress conditions. During the in- duction of systemic acquired resistance, salicylic acid production is regulated by phe- nylalanine ammonia-lyase (PAL) gene expression. In this communication, twelve-month-old tea seedlings (TV-26) were treated with benzothiadiazole (BTH) and inoculated with Lasiodiplodia theobromae. Transcript accumulation in different treat- ments, that is treated-uninoculated, untreated-inoculated and treated-inoculated were measured in comparison with untreated-uninoculated control to study the effect of BTH in defence induction. From the results, it was evident that BTH-treated and L. theobromae-inoculated plants showed higher transcript accumulation (3.81 μg/μl) and reduced disease index (3.8 ± 0.02) in comparison with untreated control where transcript accumulation was 3.26 μg/μl and disease index reduced to 14.6 ± 0.05. After sequencing, nucleotide and deduced protein sequences were compared, and 3D struc- ture was established where three lyase superfamily (cl26059) motifs were found. The increase in PAL activity was also observed in treated-inoculated plants (from 2.5 to 4.4 μmol min −1 g −1 ) in comparison with healthy control (from 2.5 to 2.7 μmol min −1 g −1 ) after 4th day of treatment. Nonetheless, BTH might be one of the significant inducers of PAL which can be used to induce of disease resistance in tea plants in India. KEYWORDS benzothiadiazole, diplodia disease, phenylpropanoids, transcript accumulation 1 | INTRODUCTION Tea (Camellia sinensis (L.) O. Kuntze.) is a tree member of the fam- ily Theaceae. Processed tea leaves are widely used as an aromatic beverage cultivated in more than 35 countries from different conti- nents. It is a rich source of antioxidant, epigallocatechin, epicatechin, gallocatechin and catechin and several other phenolic compounds that play important roles in improving human health and also providing re- sistance against a wide range of pathogens. Green leaves of tea are also used as vegetable in Burma, Thailand and also have some medicinal importance against blood pressure, coronary heart diseases and diabe- tes (Azzahra, Fouzia, Mohammed, & Noureddine, 2012; Chen, 1999;