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PH regulation of pectate lyase secretion modulates the attack of Colletotrichum gloeosporioides on avocado fruits.

ABSTRACT: Growth of Colletotrichum gloeosporioides in pectolytic enzyme-inducing medium (PEIM) increased the pH of the medium from 3. 8 to 6.5. Pectate lyase (PL) secretion was detected when the pH reached 5.8, and the level of secretion increased up to pH 6.5. PL gene (pel) transcript production began at pH 5.0 and increased up to pH 5.7. PL secretion was never detected when the pH of the inducing medium was lower than 5.8 or when C. gloeosporioides hyphae were transferred from PL-secreting conditions at pH 6.5 to pH 3.8. This behavior differed from that of polygalacturonase (PG), where pg transcripts and protein secretion were detected at pH 5.0 and continued up to 5.7. Under in vivo conditions, the pH of unripe pericarp of freshly harvested avocado (Persea americana cv. Fuerte) fruits, resistant to C. gloeosporioides attack, was 5.2, whereas in ripe fruits, when decay symptoms were expressed, the pericarp pH had increased to 6.3. Two avocado cultivars, Ardit and Ettinger, which are resistant to C. gloeosporioides attack, had pericarp pHs of less than 5.5, which did not increase during ripening. The present results suggest that host pH regulates the secretion of PL and may affect C. gloeosporioides pathogenicity. The mechanism found in avocado may have equivalents in other post-harvest pathosystems and suggests new approaches for breeding against and controlling post-harvest diseases.

SUBMITTER: Yakoby N

PROVIDER: S-EPMC91938 | biostudies-literature | 2000 Mar

REPOSITORIES: biostudies-literature

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pH regulation of pectate lyase secretion modulates the attack of Colletotrichum gloeosporioides on avocado fruits.

Yakoby N N Kobiler I I Dinoor A A Prusky D D

Applied and environmental microbiology 20000301 3

Growth of Colletotrichum gloeosporioides in pectolytic enzyme-inducing medium (PEIM) increased the pH of the medium from 3. 8 to 6.5. Pectate lyase (PL) secretion was detected when the pH reached 5.8, and the level of secretion increased up to pH 6.5. PL gene (pel) transcript production began at pH 5.0 and increased up to pH 5.7. PL secretion was never detected when the pH of the inducing medium was lower than 5.8 or when C. gloeosporioides hyphae were transferred from PL-secreting conditions at ...[more]

PMID: 10698767

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Project description:The limit of the Colletotrichum gloeosporioides species complex is defined genetically, based on a strongly supported clade within the Colletotrichum ITS gene tree. All taxa accepted within this clade are morphologically more or less typical of the broadly defined C. gloeosporioides, as it has been applied in the literature for the past 50 years. We accept 22 species plus one subspecies within the C. gloeosporioides complex. These include C. asianum, C. cordylinicola, C. fructicola, C. gloeosporioides, C. horii, C. kahawae subsp. kahawae, C. musae, C. nupharicola, C. psidii, C. siamense, C. theobromicola, C. tropicale, and C. xanthorrhoeae, along with the taxa described here as new, C. aenigma, C. aeschynomenes, C. alatae, C. alienum, C. aotearoa, C. clidemiae, C. kahawae subsp. ciggaro, C. salsolae, and C. ti, plus the nom. nov. C. queenslandicum (for C. gloeosporioides var. minus). All of the taxa are defined genetically on the basis of multi-gene phylogenies. Brief morphological descriptions are provided for species where no modern description is available. Many of the species are unable to be reliably distinguished using ITS, the official barcoding gene for fungi. Particularly problematic are a set of species genetically close to C. musae and another set of species genetically close to C. kahawae, referred to here as the Musae clade and the Kahawae clade, respectively. Each clade contains several species that are phylogenetically well supported in multi-gene analyses, but within the clades branch lengths are short because of the small number of phylogenetically informative characters, and in a few cases individual gene trees are incongruent. Some single genes or combinations of genes, such as glyceraldehyde-3-phosphate dehydrogenase and glutamine synthetase, can be used to reliably distinguish most taxa and will need to be developed as secondary barcodes for species level identification, which is important because many of these fungi are of biosecurity significance. In addition to the accepted species, notes are provided for names where a possible close relationship with C. gloeosporioides sensu lato has been suggested in the recent literature, along with all subspecific taxa and formae speciales within C. gloeosporioides and its putative teleomorph Glomerella cingulata.Taxonomic noveltiesName replacement - C. queenslandicum B. Weir & P.R. Johnst. New species - C. aenigma B. Weir & P.R. Johnst., C. aeschynomenes B. Weir & P.R. Johnst., C. alatae B. Weir & P.R. Johnst., C. alienum B. Weir & P.R. Johnst, C. aotearoa B. Weir & P.R. Johnst., C. clidemiae B. Weir & P.R. Johnst., C. salsolae B. Weir & P.R. Johnst., C. ti B. Weir & P.R. Johnst. New subspecies - C. kahawae subsp. ciggaro B. Weir & P.R. Johnst. Typification: Epitypification - C. queenslandicum B. Weir & P.R. Johnst.

Dataset Information

PH regulation of pectate lyase secretion modulates the attack of Colletotrichum gloeosporioides on avocado fruits.

Publications

pH regulation of pectate lyase secretion modulates the attack of Colletotrichum gloeosporioides on avocado fruits.

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