PLPKI: A novel serine protease inhibitor as a potential biochemical marker involved in horizontal resistance to Phytophthora infestans

Abstract

Potato leaves infected with Phytophthora infestans produced a serine protease inhibitor (PLPKI) with specificity for microbial proteases. Sequencing of the first twenty residues at the NH 2 -terminus of the mature PLPKI polypeptide demonstrated that PLPKI is a novel member of the potato protease inhibitor I family. PLPKI inhibited the activity of extracellular proteases produced by two pathogens of potato, P. infestans and Rhizoctonia solani, but was inactive against proteases secreted into the culture media by the binucleate Rhizoctonia N2, a non-pathogenic fungus for potato. Western blot analysis showed a positive correlation between the levels of PLPKI and the degree of horizontal resistance, showing its highest accumulation in clone OKA 5632.11, which has been described as highly resistant. This correlation, together with the ability of PLPKI to completely abolish the secreted serine protease activity of P. infestans, suggests that PLPKI may have an active role in protecting potato plants from this pathogenic oomycete and that it could be used as a suitable biochemical marker to help breeders in the selection of cultivars with high degree of horizontal resistance.

Transcript profiling of serine- and cysteine protease inhibitors inTriticum aestivumvarieties with different drought tolerance

“…Elucidating the differential expression of such genes in resistant and susceptible varieties could contribute to novel strategies in markerassisted breeding of crops with improved tolerance to biotic and abiotic stresses (Feldman et al 2014;Yarullina et al 2014). In the present study we monitored the expression of a published T. aestivum Bowman-Birk type proteinase inhibitor WALI3 under drought and recovery.…”

Secondary Metabolites, Other Prospective Substances, and Alternative Approaches That Could Promote Resistance against Phytophthora infestans

“…Different proteomics studies targeting leaves, tubers, and secreted proteins in the apoplast have extended the list of putative resistance markers. These studies have identified the expected targets (R proteins, osmotins, peroxidases, protease inhibitors, and lipid transfer proteins), as well as transcription factors and multiple defense-related proteins, including glutathione S-transferases, endochitinase, glycosyltransferase, glucosidases, and heat shock proteins 70 [138,194,[196][197][198][199][200][201][202][203][204]. However, most of these candidates for MAS need to be validated in dedicated mechanistic studies.…”

Efficacy of seed defense proteins in biofortified pearl millet lines against blast and downy mildew

“…PIs (PR-6) are storage proteins that act as a natural phytochemical defense by inactivating the proteases responsible for the growth and survival of fungal pathogens as well as insect pests. As antifungal compounds, they inhibit mycelial extracellular proteases which play a pivotal role in nutrient acquisition from the host plant (Silva et al 2013;Feldman et al 2014). While as pesticidal compounds, they irreversibly inactivate larval digestive proteases, in turn, generate critical amino acid deficiency in various metabolic processes, and eventually lead to developmental abnormalities and mortality of pests (Swathi et al 2016;Lokya et al 2020).…”

“…While as pesticidal compounds, they irreversibly inactivate larval digestive proteases, in turn, generate critical amino acid deficiency in various metabolic processes, and eventually lead to developmental abnormalities and mortality of pests (Swathi et al 2016;Lokya et al 2020). Furthermore, identification of these proteins along with other defense molecules serves as biochemical markers in the differentiation of resistant and susceptible lines, and may also be helpful in resistance breeding (Kini et al 2000;Feldman et al 2014). Considering the importance of defense proteins in disease resistance, the present study was aimed to characterize the seed proteins extruded from 25 biofortified inbred lines of pearl millet for the presence of PIs, β-1,3glucanases, chitinases, and cellulases, and correlate their expression levels with the blast and downy mildew disease resistance of the respective lines.…”