New insight in the study of strawberry fungal pathogens (original) (raw)
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New Insights in the Study of Strawberry Fungal Pathogens
Strawberry (Fragaria ananassa) is one of the world's most commercially important fruit crops, and is grown in many countries The commercial viability of the crop is continually subject to various risks, one of the most serious of which is the diseases caused by phytopathogenic organisms. More than 50 different genera of fungi can affect this cultivar, including Botrytis spp., Colletotrichum spp., Verticillium spp., and Phytophthora spp. The development of new molecular biology technologies, based on genomics, transcriptomics and proteomics approaches, is revealing new insights on the diverse pathogenicity factors causing fungal invasion, degradation and destruction of the fruit (in planta and during storage and transport). Researchers have focused attention on the plant's own defence mechanisms against these pathogens. In this review, advances in the study and detection of fungal plant pathogens, new biocontrol methods, and proteomic approaches are described and the natural defence mechanisms recently discovered are reported.
Frontiers in Plant Science, 2019
Gray mold caused by Botrytis cinerea is a major cause of economic losses in strawberry fruit production, limiting fruit shelf life and commercialization. When the fungus infects Fragaria × ananassa strawberry at flowering or unripe fruit stages, symptoms develop after an extended latent phase on ripe fruits before or after harvesting. To elucidate the growth kinetics of B. cinerea on flower/fruit and the molecular responses associated with low susceptibility of unripe fruit stages, woodland strawberry Fragaria vesca flowers and fruits, at unripe white and ripe red stages, were inoculated with B. cinerea. Quantification of fungal genomic DNA within 72 h postinoculation (hpi) showed limited fungal growth on open flower and white fruit, while on red fruit, the growth was exponential starting from 24 hpi and sporulation was observed within 48 hpi. RNA sequencing applied to white and red fruit at 24 hpi showed that a total of 2,141 genes (12.5% of the total expressed genes) were differentially expressed due to B. cinerea infection. A broad transcriptional reprogramming was observed in both unripe and ripe fruits, involving in particular receptor and signaling, secondary metabolites, and defense response pathways. Membranelocalized receptor-like kinases and nucleotide-binding site leucine-rich repeat genes were predominant in the surveillance system of the fruits, most of them being downregulated in white fruits and upregulated in red fruits. In general, unripe fruits exhibited a stronger defense response than red fruits. Genes encoding for pathogenesis-related proteins and flavonoid polyphenols as well as genes involved in cell-wall strengthening were upregulated, while cell-softening genes appeared to be switched off. As a result, B. cinerea remained quiescent in white fruits, while it was able to colonize ripe red fruits.
XXVIII International Horticultural Congress on Science and Horticulture for People (IHC2010): International Symposium on Genomics and Genetic Transformation of Horticultural Crops, 2012
Strawberry (Fragaria × ananassa) yields are strongly affected by fungal diseases and pests, e.g., Colletotrichum spp., forcing the excessive use of chemical products (mostly environmental contaminants) to control them. Resistant cultivars are a priority of most strawberry breeding programs; however, little is known about the genetic basis for strawberry's resistance to pathogens, and completely resistant cultivars have not been reported. Although molecular markers of disease resistance in strawberry have been reported, the octoploid genetic structure of commercial strawberry makes it difficult to associate molecular markers with disease resistance genes. To gain insights into the genetic mechanisms of defense against Colletotrichum acutatum, the transcriptome of two strawberry cultivars ('Camarosa' and 'Andana') exhibiting different susceptibility to this pathogen has been analyzed. An in-house cDNA microarray based on a 3264 strawberry probe set was fabricated from a strawberry differential ESTs collection previously obtained in response to this pathogen. Transcriptional comparison of these two cultivars was performed before and after infection. The expression of 190 genes was significantly altered, of which, 94 and 50 genes, were exclusively alterated in cultivars 'Camarosa' and 'Andana', respectively. Over-expression and siRNA approaches are being used for functional analysis of candidate genes. Valuable information is being generated as a tool for effective control strategies to increase resistance in strawberry.
Analysis of strawberry genes differentially expressed in response to Colletotrichum infection
Physiologia Plantarum, 2006
Important losses in strawberry production are caused by species of the fungus Colletotrichum, the causal agent of anthracnose. However, very limited studies at molecular level exist of the mechanisms related to strawberry susceptibility against this pathogen. We have analysed a moderately resistant cultivar (cv. Andana) together with a very susceptible one (cv. Camarosa) during the process of infection with Colletotrichum acutatum at a molecular level. To gain insight into this interaction we have identified a large number of strawberry genes involved in signalling, transcriptional control, defence and many genes with unknown function with altered expression in response to C. acutatum infection. Spatial and temporal gene expression profiles after infection showed that the response was dependant on the tissue and cultivar analysed and also quicker and/or stronger in the moderately resistant cultivar (cv. Andana) than in the susceptible one (cv. Camarosa). Interestingly, we found that genes described as being induced during pathogen infection such as g-thionins, peroxidases, chitinases and b-1-3-glucanases were downregulated in fruit and/ or crown tissues of the very susceptible cultivar. Our results yielded a first insight on some of the genes responding to this plant-pathogen interaction at molecular level and suggest that pathogen progression can be dependent upon a reduction of the active defences of strawberry and this is genotype and tissue dependent.
Proteomic Advances in Phytopathogenic Fungi
Current Proteomics, 2007
Phytopathogenic fungi are organisms responsible for several plant diseases in different crops around the world, causing very important economic losses to the farmers. Fungi have a complicated life cycle, normally with asexual and sexual reproduction that involves the formation of different reproductive structures. Moreover, during plant disease, fungi produce different components that are essential to complete the infection process (enzymes, toxins, etc) and are named "pathogenicity factors".
The Strawberry Plant Defense Mechanism: A Molecular Review
Plant and Cell Physiology, 2011
Strawberry, a small fruit crop of great importance throughout the world, has been considered a model plant system for Rosaceae, and is susceptible to a large variety of phytopathogenic organisms. Most components and mechanisms of the strawberry defense network remain poorly understood. However, from current knowledge, it seems clear that the ability of a strawberry plant to respond efficiently to pathogens relies first on the physiological status of injured tissue (pre-formed mechanisms of defense) and secondly on the general ability to recognize and identify the invaders by surface plant receptors, followed by a broad range of induced mechanisms, which include cell wall reinforcement, production of reactive oxygen species, phytoalexin generation and pathogenesis-related protein accumulation. Dissection of these physiological responses at a molecular level will provide valuable information to improve future breeding strategies for new strawberry varieties and to engineer strawberry plants for durable and broad-spectrum disease resistance. In turn, this will lead to a reduction in use of chemicals and in environmental risks. Advances in the understanding of the molecular interplay between plant (mainly those considered model systems) and various classes of microbial pathogens have been made in the last two decades. However, major progress in the genetics and molecular biology of strawberry is still needed to uncover fully the way in which this elaborate plant innate immune system works. These fundamental insights will provide a conceptual framework for rational human intervention through new strawberry research approaches. In this review, we will provide a comprehensive overview and discuss recent advances in molecular research on strawberry defense mechanisms against pathogens.
The strawberry gene Cyf1 encodes a phytocystatin with antifungal properties
Journal of Experimental Botany, 2005
An EST, encoding a strawberry phytocystatin (PhyCys) obtained from a developing fruit of Fragaria3ananassa cv. Elsanta has been characterized. The corresponding gene (Cyf1) had three introns interrupting its ORF that codes for a protein (FaCPI-1) of 235 amino acid residues with a putative signal peptide of 29 residues and an estimated molecular mass for the mature protein of 23.1 kDa. This protein contains, besides a C-terminal extension, several motifs conserved in all members of the PhyCys superfamily: (i) a GG and LARFAV-like motifs towards the N-terminal part of the protein; (ii) the reactive site QVVAG, and (iii) a conserved PW, downstream of the reactive site. Northern blot and in situ hybridization analyses indicated that the Cyf1 gene was expressed in fully expanded leaves, in roots and in achenes, but not in the receptacle (pseudocarp) during fruit development. The recombinant FaCPI-1 protein expressed in E. coli efficiently inhibited papain (K i 1.9310 29 M) and less so cathepsin H (K i 4.73 10 27 M) and cathepsin B (K i 3.3310 26 M), and was a good inhibitor of the in vitro growth of phytopathogenic fungi Botrytis cinerea (EC 50 : 1.90 lM) and Fusarium oxysporum (EC 50 : 2.28 lM).
Plant Pathology, 2011
Microscopic investigations were conducted into the interaction of Colletotrichum acutatum on white and red strawberry (Fragaria ·ananassa) fruit surfaces. The results showed that, whilst the early interaction events were similar in both white and red fruits, after 24 h fungal colonization dramatically varied: in white fruits C. acutatum became quiescent as melanized appressoria, but on red fruits it displayed subcuticular necrotrophic invasion. A microarray analysis of white and red strawberries after 24 h of interaction with C. acutatum was performed, in order to reveal differences in gene expression possibly related to the different susceptibility of unripe and ripe fruits. Epi ⁄ catechin-related genes and fatty acid metabolism genes, involved in the production of quiescence-related molecules such as flavan-3-ols, proanthocyanidins and antifungal dienes, were found to be regulated during strawberry ripening, supporting a role for these molecules as preformed defence mechanisms. Besides several genes commonly regulated upon pathogen interaction, different genes were specifically transcribed only in white or red challenged fruits; a number of these, such as those coding for lectin and polyphenol oxidase, possibly account for specific pathogen-induced responses. The putative biological role of these genes in the different susceptibility of fruits to C. acutatum is discussed.