Expression Profiling of Castanea Genes during Resistant and Susceptible Interactions with the Oomycete Pathogen Phytophthora cinnamomi Reveal Possible Mechanisms of Immunity

Abstract

The most dangerous pathogen affecting the production of chestnuts is Phytophthora cinnamomi a hemibiotrophic that causes root rot, also known as ink disease. Little information has been acquired in chestnut on the molecular defense strategies against this pathogen. The expression of eight candidate genes potentially involved in the defense to P. cinnamomi was quantified by digital PCR in Castanea genotypes showing different susceptibility to the pathogen. Seven of the eight candidate genes displayed differentially expressed levels depending on genotype and time-point after inoculation. Cast_Gnk2-like revealed to be the most expressed gene across all experiments and the one that best discriminates between susceptible and resistant genotypes. Our data suggest that the pre-formed defenses are crucial for the resistance of C. crenata to P. cinnamomi. A lower and delayed expression of the eight studied genes was found in the susceptible Castanea sativa, which may be related with the establishment and spread of the disease in this species. A working model integrating the obtained results is presented.

First interspecific genetic linkage map for Castanea sativa x Castanea crenata revealed QTLs for resistance to Phytophthora cinnamomi

“…Presence of putative resistance proteins, cellulose synthase, regulation of gene expression and hormone signaling may be involved in P . cinnamomi resistance, as it has been suggested by previous studies of tree- Phytophthora interactions [28–31]. The strongest evidence that the QTLs identified here underlie resistance candidate genes, corresponds to the mapping of markers associated to resistance proteins (NDR1/HIN1-Like protein 3) [20] and to the mapping of AC_32934_470 and AC_36335_960 markers on LG_E and LG_K, respectively.…”

“…Therefore, they may be candidates for downstream studies and applications. In this context, the expression level of transcripts belonging to MYB/SANT and Zinc Finger families have been quantified for three progenies and parents of the breeding program [31]. This recent study showed that Myb4 gene (containing a MYB/SANT domain) may be involved in the chestnut resistance mechanism in C .…”

“…This recent study showed that Myb4 gene (containing a MYB/SANT domain) may be involved in the chestnut resistance mechanism in C . crenata and in hybrid resistant genotypes, by regulating salicylic acid signaling or lignin synthesis in order to avoid pathogen progression [31]. The function of the putative resistance genes underlying the QTLs identified will be confirmed in further research using transcriptomics, proteomics and functional analysis.…”

Canker and decline diseases caused by soil- and airborne Phytophthora species in forests and woodlands

“…Planting of infested nursery stock and movement of contaminated substrates are the main pathways of short and long-distance inoculum dispersal ( Jung et al 2016 ). The existence of genetic variability in susceptibility to P. × cambivora in C. sativa and resistance to P. cinnamomi in some clones of C. sativa and in many clones of the Euroasiatic chestnut hybrids C. crenata × C. sativa and C. molissima × C. sativa could provide the basis for a resistance screening programme necessary for a long-term management of ink disease in Europe ( Robin et al 2006 , Miranda-Fontaíña et al 2007 , Costa et al 2011 , Santos et al 2015 , 2017a , b ).…”

Good Riddance? Breaking Disease Susceptibility in the Era of New Breeding Technologies

“…In vivo protein-protein interaction screens are yet another suitable approach to identify susceptibility factors using effector proteins as bait [18,19]. Candidate susceptibility genes were also identified via host gene expression profiling, as it was shown with Hyaloperonospora arabidopsidis-infected Arabidopsis thaliana and Phytophthora cinnamoni-infected Castanea [20,21]. Once an S gene is identified, studying the physiological function of the susceptibility factor and genetic or physical interactions can identify susceptibility mechanisms or associated pathways and thereby new susceptibility factors [22,23].…”