Protease inhibitors as stress-responsive effectors in potato: Biotechnological applications

Abstract

A bioinformatic analysis allowed us to identify 142 protease inhibitors (PIs) in the potato genome. This multigene family regulates protein turn-over preventing catabolism of essential proteins during metabolic processes and plays a role in the defense against heterologous proteases from pathogens and pests. PIs have been proposed as an alternative to chemical pesticides for the control of herbivorous insects, and as abiotic stress-protective factors. However, an unbalanced expression of PIs may compromise plant’s endogenous proteolytic processes. Thus, it is very important to explore which endogenous processes they regulate, which are their specific targets, and how their activity is regulated. According to RNAseq data available at the SPUD DB, five PIs are among the 49 genes induced upon different abiotic, biotic and hormone treatments. Three of them, Soltu.DM.03G018520, Soltu.DM.03G018580 and Soltu.DM.03G018600, are Kunitz-type PIs (KTIs) located in a QTL for Phytophthora infestans resistance in chromosome 3 at 43 Mbp. Soltu.DM.03G018520 and Soltu.DM.03G018580 are among the most expressed genes in the genome under control conditions. RT-qPCR assays performed using RNA from in-vitro plants cultured under control conditions or exposed to 150 mM NaCl during 24 h, confirmed the induction of these two KTIs under salt stress. Currently we are conducting expression analysis in plant tissues and in plants exposed to long-term (3 weeks) salt stress. In the future we aim to characterize these genes in overexpressing or knockdown plants to elucidate their potential as biotechnological tools.