Quantitative resistance in potato leaves to late blight associated with induced hydroxycinnamic acid amides

Abstract

Late blight is a serious economic threat to potato crop, sometimes leading to complete crop loss. The resistance in potato to late blight can be qualitative or quantitative in nature. Qualitative resistance is not durable. Though quantitative resistance is durable, the breeding is challenging due to polygenic inheritance. Several quantitative trait loci (QTLs) have been identified, but the mechanisms of resistance are largely unknown. A nontargeted metabolomics approach was used to identify resistance-related (RR) metabolites in a resistant genotype (F06025), as compared to a susceptible (Shepody) genotype, mock- or pathogen-inoculated. The RR metabolites, which had high fold change in abundance, mainly belonged to phenylpropanoid, flavonoid, fatty acid, and alkaloid chemical groups. The most important phenylpropanoids identified were hydroxycinnamic acid amides, the polyaromatic domain of suberin that is known to be associated with cell wall reinforcement. These metabolites were mapped on to the potato metabolic pathways, and the candidate enzymes and their coding genes were identified. A quantitative reverse transcription polymerase chain reaction (qRT-PCR) assay revealed a higher upregulation of 4-coumarate: CoA ligase (4-CL), tyrosine decarboxylase (TyDC), and tyramine hydroxycinnamoyl transferase (THT) in the pathogen-inoculated resistant genotype than in susceptible. These genes were sequenced in both resistant and susceptible genotypes, and nonsynonymous single-nucleotide polymorphisms (nsSNPs) were found. The application of these genes in potato resistance improvement, following validation, is discussed.

Germin-like protein 2 gene promoter from rice is responsive to fungal pathogens in transgenic potato plants

“…In a recent report, Yogendra et al (2014) quantitatively analyzed the pathogen resistance-related genes of linked enzymes, tyrosine decarboxylase (TyDC), CoA ligase (4-CL), and tyraminehydroxycinnamoyltransferase (THT), in the pathogen-inoculated resistant and susceptible potato genotype, so as to validate the significance of these genes in the improvement of potato resistance in response to pathogen infection. Furthermore, in an earlier study, Yevtushenko et al (2004) reported that the win3.12T wound-inducible promoter from poplar was systemically active in aerial regions of potato plants under fungal stress.…”

Plant Innate Immune Response: Qualitative and Quantitative Resistance

“…The resistance related proteins (RRP) are the pathogenesis-related (PR) proteins that suppress pathogens, detoxify toxins or virulence factors produced by pathogens and prevent pathogen advancement by enforcing cell walls (Egorov and Odintsova, 2012;ºazniewska et al, 2012). The resistance related metabolites (RRM) may be antimicrobial, such as phytoanticipins and phytoalexins, or may form complex conjugates that are deposited to reinforce cell walls and suppress pathogen progress (Boller and Felix, 2009;Nawrot et al, 2014;Yogendra et al, 2014). Polymorphisms in introns, exons, and promoter regions, especially in the domain sequence, of these hierarchy of R genes determine the functionality of the proteins/enzymes produced, and thus the amount of proteins (RRP) and metabolites (RRM) biosynthesized (Eudes et al, 2014;Krattinger et al, 2009;Pushpa et al, 2014;Yogendra et al, 2015b;Yogendra et al, 2014).…”

“…The resistance related metabolites (RRM) may be antimicrobial, such as phytoanticipins and phytoalexins, or may form complex conjugates that are deposited to reinforce cell walls and suppress pathogen progress (Boller and Felix, 2009;Nawrot et al, 2014;Yogendra et al, 2014). Polymorphisms in introns, exons, and promoter regions, especially in the domain sequence, of these hierarchy of R genes determine the functionality of the proteins/enzymes produced, and thus the amount of proteins (RRP) and metabolites (RRM) biosynthesized (Eudes et al, 2014;Krattinger et al, 2009;Pushpa et al, 2014;Yogendra et al, 2015b;Yogendra et al, 2014). Thus, the amount of RRP or RRM biosynthesized by an R gene is significantly controlled by a hierarchy of regulatory R genes, especially the TFs, activated following the perception of elicitors/effectors.…”

“…Kaempferol and quercetin glycosides: Flavonol glycosides form a hard, crystalline structure as a physical barrier against pathogens. Kaempferol, quercetins, and their glycosylated forms prevent the spread of F. graminearum in barley (Bollina et al, 2010;Kumaraswamy et al, 2012) and P. infestans in potato (Fellenberg and Vogt, 2015;Pushpa et al, 2014;Yogendra et al, 2014). Pectin-alkaloid: Pectins are primary cell wall components and following pathogen invasion they conjugate with alkaloids and deposit to enforce secondary cell walls (Didi et al, 2015).…”

“…Suberin: Suberins are polymers of polyaromatic, such as hydroxycinnamic acid, and polyaliphatic, such as v-hydroxy acid, metabolites. They are deposited not only in periderm but also in xylem Vishwanath et al, 2015;Yogendra et al, 2014).…”