title: Expression analysis of chitinase upon challenge inoculation toAlternariawounding and defense inducers inBrassica juncea.
abstract: Chitinases are the hydrolytic enzymes which belong to the pathogenesis-related (PR) protein family and play an important role not only in plant defense but also in various abiotic stresses. However, only a limited number of chitinase genes have been characterised inB. juncea. In this study, we have characterisedB. junceaclass IV chitinase gene (accession no EF586206) in response to fungal infection, salicylic acid (SA), jasmonic acid (JA) treatments and wounding. Gene expression studies revealed that the transcript levels ofBjchitinase(BjChp) gene increases significantly both in local and distal tissues afterAlternariainfection.Bjchitinasegene was also induced by jasmonic acid and wounding but moderately by salicylic acid. A 2.5 kb class IV chitinase promoter of this gene was isolated fromB. junceaby Genome walking (accession no KF055403.1).In-silicoanalysis of this promoter revealed a number of conservedcis-regulatory elements related to defense, wounding and signalling molecules like SA, and JA. For validation, chitinase promoter was fused to the GUS gene, and the resultant construct was then introduced intoArabidopsisplants. Histochemical analysis of T2transgenic Arabidopsis plants showed that higher GUS activity in leaves after fungal infection, wounding and JA treatment but weakly by SA. GUS activity was seen in meristematic tissues, young leaves, seeds and siliques. Finally investigation has led to the identification of a pathogen-inducible, developmentally regulated and organ-specific promoter. Present study revealed thatBjchitinase(BjChp) promoter is induced during biotic and environmental stress and it can be used in developing finely tuned transgenics.
authors.affiliation: National Research Centre on Plant Biotechnology, Pusa Campus, New Delhi, 110012, India; Fakir Mohan University, Vyasa Vihar, Balasore, Orissa 756020, India.
authors.forename: Sandhya
authors.initials: S
authors.lastname: Rawat
authors.affiliation: National Research Centre on Plant Biotechnology, Pusa Campus, New Delhi, 110012, India.
authors.forename: Sajad
authors.initials: S
authors.lastname: Ali
authors.affiliation: Fakir Mohan University, Vyasa Vihar, Balasore, Orissa 756020, India.
authors.forename: Bhabatosh
authors.initials: B
authors.lastname: Mittra
authors.affiliation: National Research Centre on Plant Biotechnology, Pusa Campus, New Delhi, 110012, India.
authors.forename: Anita
authors.initials: A
authors.lastname: Grover
keywords: Alternaria brassicae; Brassica juncea; Chitinase promoter; Resistance