β‐Aminobutyric Acid Primed Expression of WRKY and Defence Genes in Brassica carinata Against Alternaria Blight

Foliar spray with BABA led to a significant reduction of lesion development in Brassica carinata caused by Alternaria brassicae. To get better insight into molecular mechanisms underlying priming of defence responses by BABA, expression pattern of BcWRKY genes and marker genes for the SA and JA pathway namely PR‐1 and PDF 1.2 was examined. Q‐RT‐PCR analysis revealed priming of BcWRKY70, BcWRKY11 and BcWRKY53 gene expression in BABA‐pretreated Brassica plants challenged with pathogen. However, the expression of BcWRKY72 and BcWRKY18 remained unchanged. Furthermore, BcWRKY7 gene was found to be upregulated in water‐treated plants in response to pathogen indicating its role in susceptibility. In addition, BABA application potentiated expression of defence genes PR‐1, PDF1.2 and PAL in response to the pathogen. In conclusion, BABA‐primed expression of BcWRKY70, BcWRKY11 and BcWRKY53 genes is strongly correlated with enhanced expression of PR‐1, PDF1.2 and PAL hence suggesting their role in BABA‐induced resistance.