Simultaneous quantification of sporangia and zoospores in a biotrophic oomycete with an automatic particle analyzer: Disentangling dispersal and infection potentials

Adaptation of a plant pathogen to partial host resistance: selection for greater aggressiveness in grapevine downy mildew

“…The negative correlation between sporangium number and size found for these 103 pathogen isolates confirms previous findings published by Delmas et al. () and Delmotte et al. ().…”

“…3), of the same order of magnitude as previous reports for this pathosystem (Delmas et al. ; Delmotte et al. ).…”

“…In P. viticola , sporangium production (and therefore transmission capacity) is positively correlated with zoospore production (infection capacity), regardless of sporangium size (Delmas et al. ). Adapted isolates of P. viticola producing more sporangia are thus more infective in the next generation of the pathogen cycle and probably have a selective advantage, even if they produce smaller sporangia.…”

“…However, on the susceptible host, adapted isolates produced smaller spores and tended to have higher sporulation rates, suggesting a lower infection potential in the next generation (Delmas et al. ) and faster sporulation dynamics on susceptible hosts, respectively. However, the lack of evidence for fitness costs should be interpreted with care.…”

“…We gently washed each leaf disc separately in 10 mL of saline (Isoton II; Beckman Coulter) to collect sporangia. We determined the number of sporangia per mm² (cumulative, over 5 days of infection) and weighted sporangium size, as described by Delmas et al (2014). The latency period was estimated by visually checking leaf discs daily under a stereomicroscope and recording the day of first sporulation for each disc.…”