Zoosporangial root infection of tomato by Spongospora subterranea in hydroponic and glasshouse culture results in diminished plant growth

Abstract

Tomato plants are highly susceptible to root infection by Spongospora subterranea and are commonly used as bioassay hosts. The impacts of root infection with S. subterranea on plant productivity and yield have been debated. Recent experiments with potato, the major economic host of S. subterranea, have indicated significantly reduced plant growth and potato yield following heavy infection. However, there have been very few similar studies that have examined the possible impacts of S. subterranea infection on tomato plant growth. Three tomato cultivars, “Grape,” “Roma” and “Truss,” were challenged with S. subterranea inoculum in hydroponic culture. Moderate to severe zoosporangial infections were observed with minor but statistically significant differences in susceptibility among the three tomato cultivars. Zoosporangial root infection in the absence of root gall formation resulted in significantly diminished shoot lengths and plant fresh weights in pathogen challenge tests conducted both in hydroponic culture and glasshouse‐grown plants in potting mix. Root lengths were reduced, but the differences were statistically significant in a single trial only. The findings from this study demonstrate that, as with potato, root infection by S. subterranea can result in reduced tomato plant growth and that root gall production associated with root infection was not necessary for this retardation of growth response. This further suggests that possible yield impacts in other crop species that are hosts for S. subterranea root infection are worthy of examination.

Moments of weaknesses – exploiting vulnerabilities between germination and encystment in the Phytomyxea

“…The secondary zoospores are morphologically indistinguishable from primary zoospores but may be slightly larger (Tamada & Asher, 2016). Together they may re‐infect plant tissues in a polycyclic manner as seen in S. subterranea (Balendres et al ., 2018). Conversely, in P. brassicae infection is monocyclic (Howard et al ., 2010); the reason for this difference is however unclear.…”

Susceptibility of opium poppy and pyrethrum to root infection by Spongospora subterranea

“…Tomato was more susceptible to S. subterranea root disease than opium poppy, which was in turn more susceptible than py- Shah, Falloon, Butler, & Lister, 2012;Hernandez Maldonado et al, 2013;Falloon et al, 2016). Reduced growth in tomato grown in glasshouse or hydroponic culture has also been previously documented (Nielsen & Larsen, 2004;Balendres et al, 2018), although the impacts on growth in field grown plants and on quantity and quality of fruit remain to be tested. The extent of root infection in opium poppy and pyrethrum plants was less than that seen in tomato, and the impacts on plant growth were not significant.…”

“…The susceptibility of opium poppy and pyrethrum to root infection with S. subterranea was tested and compared to tomato cv. Grape (Solanum esculentum), a known host (Balendres, Tegg, Amponsah, & Wilson, 2018) in two glasshouse pathogen challenge trials.…”

Draft Genome Resource for the Potato Powdery Scab Pathogen Spongospora subterranea

“…It causes powdery scab of potato tubers, root galling in its host, reduces tuber yield, and transmits the Potato mop-top virus (PMTV) (genus Pomovirus , family Virgaviridae ) (Balendres et al 2016; Falloon et al 2016). It can also diminish the growth of other solanaceous crops, such as tomatoes ( Solanum lycopersicum ) (Balendres et al 2018). Because of their intracellular growth and obligate host–dependent life style, genomic data for plasmodiophorids are rare, although those pathogens cause substantial crop damage, e.g., in brassicas, sugar beet, or gramineous crops (Schwelm et al 2018).…”