C. fioriniae was formally described as a variety of Colletotrichum acutatum in 2008,[4] and as its own species shortly thereafter.[5] However, while it had not previously been recognized as a separate species, when grown on potato dextrose agar it produces a distinct pink to maroon red color on the bottom side and was described in historical studies as "chromogenic" isolates of Glomerella cingulata.[6][7][8] It is currently recognized as a species within the C. acutatumspecies complex.[1]
Identification
C. fioriniae produces conidia that are smooth-walled, hyaline (glassy and translucent), with acute (pointed) ends, measuring about 15 x 4.5 microns.[1] When grown on potato dextrose agar it usually produces a pink to dark red chromogenic color on the reverse side. However, these morphological characteristic overlap with those of other species in the C. acutatum species complex, so definitive identification requires the sequencing of DNA barcoding regions such as the internally transcribed spacer (ITS), or introns in the GAPDH, histone3, beta-tubulin, or actin genes.[9]
Reproduction
Like other species in the C. acutatum species complex, C. fioriniae reproduces almost exclusively via the production of asexual spores called conidia.[10][1] These conidia are often produced in sticky gelatinous orange masses that are rain-splash dispersed.[10][11] Conidia are mostly produced at temperatures from 10 to 30 °C, such that in temperate deciduous forests and orchards rain-splash dispersal occurs from bud-break to leaf drop.[12]
Pathogenic lifestyle
As a plant pathogen, C. fioriniae has a hemibiotrophic lifestyle, where infections are initially biotrophic (or latent or quiescent, depending on the point of view) before switching to necrotrophy and active killing of the plant cells.[10]
