Comparative proteomics of Pinus–Fusarium circinatum interactions reveal metabolic clues to biotic stress resistance

Abstract

Fusarium circinatum, causing pine pitch canker (PPC), affects conifers productivity and health worldwide. Selection and breeding for resistance arises as the most promising approach to fight PPC. Therefore, it is crucial to explore the response of hosts with varying levels of susceptibility to PPC to unveil the genes/pathways behind these phenotypes. We evaluated the dynamics of the needle proteome of a susceptible (Pinus radiata) and a relatively resistant (Pinus pinea) species upon F. circinatum inoculation by GeLC-MS/MS. Integration with physiological data and validation of key genes by qPCR allowed to identify core pathways regulating these contrasting responses. In P. radiata, the pathogen may target both the secondary metabolism to negatively regulate immune response and chloroplast redox proteins to increase energy-producing pathways for amino acid production in its favour. In contrast, chloroplast redox regulation may assure redox homeostasis in P. pinea, as well as nonenzymatic antioxidants. The presence of membrane trafficking-related proteins exclusively in P. pinea likely explains its defence response against F. circinatum. A crosstalk between abscisic acid and epigenetic regulation of gene expression is also proposed in PPC response. These results are useful to support breeding programs aiming to achieve PPC resistance. 1 | INTRODUCTION Pine pitch canker (PPC), caused by Fusarium circinatum Nirenberg & O'Donnell, is one of the most important conifer diseases worldwide (Wingfield et al. 2008) affecting more than 60 Pinus species, as well as Pseudotsuga menziesii (Mirb.) Franco (Bezos et al. 2017). In Europe, 10 million ha of pine forest were estimated to be at risk of F. circinatum infection (EFSA 2010) and thus emergency measures have been established to avoid its introduction and spread (Commission Decision 2007/433/EC). Given the current European restrictions regarding fungicide application in forests (Directive 2009/128/EC), several environmentally friendly methods have been proposed to control PPC, with selection and breeding for resistance arising as the most promising (Martín-García et al. 2019). Resistance to forest tree diseases may be achieved via two nonexclusive approaches (Naidoo et al. 2019): (a) breeding programs supported

Unravelling pine response to Fusarium circinatum through Raman spectroscopy

“…[ 72 ] The induction of the phenylpropanoids pathway has been previously reported in P. radiata after F. circinatum infection, [ 15,35,57 ] with recent proteomics studies suggesting that the host's secondary metabolism (e.g., lignans biosynthesis) may be targeted by the pathogen to negatively regulate pine immune response. [ 19 ] This is in accordance with the higher levels of phenolic compounds detected in inoculated P. radiata by RS. Raman data further indicates differences in the lignin subunits deposited in inoculated P. radiata plants, and thus structural differences in the lignin between inoculated and non‐inoculated samples.…”

“…[14][15][16][17][18] These have recently been complemented with physiological, multi-omics, and rhizobiome studies comparing one of the most PPC susceptible pine species (Pinus radiata D. Don) with a relatively resistant one (Pinus pinea L.) aiming to explore the onset of disease and identify specific mechanisms that may explain the differential responses observed. [12,[19][20][21][22] However, advances on the development of early detection tools for PPC are still lacking.…”

Proteomics research in forest trees: A 2012-2022 update

“…Biotic stress research has also used genetic variance and proteomics aiming in this case at identifying the proteins responsible for resistance/susceptibility to two main pathogens affecting pine species worldwide currently: the fungus Fusarium circinatum , responsible for the pine pitch canker ( Wingfield et al., 2008 ; Amaral et al., 2021 ; Amaral et al., 2022 ), and the pine wood nematode Bursaphelencus xylophilus , causing pine wilt ( Espada et al., 2022 ). Comparative proteome analysis of the differential response of pine species upon F. cicinatum inoculation revealed that susceptibility was associated with proteins involved in negative regulation of plant immunity, and increased energy production and amino acid synthesis pathways related to changes in plant secondary metabolism and chloroplast redox balance.…”

“…Comparative proteome analysis of the differential response of pine species upon F. cicinatum inoculation revealed that susceptibility was associated with proteins involved in negative regulation of plant immunity, and increased energy production and amino acid synthesis pathways related to changes in plant secondary metabolism and chloroplast redox balance. In turn, proteins related to vesicle trafficking and the crosstalk between ABA and epigenetic regulation were associated with pathogen resistance ( Amaral et al., 2021 ). Similar approaches have been used to study the interaction between pine species and the pine wood nematode, B. xylophilus .…”

Multispecies comparison of host responses to Fusarium circinatum challenge in tropical pines show consistency in resistance mechanisms

“…Induced defences require pathogen/pest recognition either through microbe‐/damage‐associated molecular patterns (MAMPs/DAMPs), resulting in pattern triggered immunity (PTI), or effector recognition by host resistance (R) proteins, resulting in effector triggered immunity (ETI; Agrios, 2005; Dodds & Rathjen, 2010; Jones & Dangl, 2006; Spoel & Dong, 2012). The majority of plant R proteins consist of nucleotide‐binding leucine rich repeat (NLR) receptors (Baggs et al, 2017; Głowacki et al, 2011).…”