Objective Basic characteristics and evolutional relationship on the phenylpropane metabolic pathway associated with the pepper blast disease that ill-affects the cultivation and production of the globally important spice, black peppers, were studied.
Method The phenylpropane metabolic pathway was believed to be key to the blast resistance of black peppers, and phenylalanine ammonialyase (PAL) to be the crucial, rate-limiting enzyme in the pathway. Hence, based on the transcriptomics of a resistant black pepper germplasm the sequences of 14 PALs were identified and named PnPAL1-PnPAL14. Their bioinformatics and expression patterns were analyzed.
Result The gene family had a theoretical isoelectric point between pH 5.76 and 9.77 with a molecular weight between 7.37441 kDa and 83.43107 kDa. Seven of the identified PnPALs contained 8 motifs and PLN02457 conserved domains. They belonged to the PnPAL family that consisted of many stress response elements, especially salicylic acid, methyl jasmonate, and other cis-acting elements, which are known to resist the pathogenic invasion. The PnPALs were located at the base of the phylogenetic tree, being relatively old and holding a status like black peppers. PnPAL10 expressed in an up-regulation trend after a pathogenic induction suggesting a close relation of the gene to the blast resistance of the plant.
Conclusion A critical role the PnPAL family played in the blast resistance of black peppers was positively identified.
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