Spatio-temporal connectivity and host resistance influence evolutionary and epidemiological dynamics of the canola pathogen Leptosphaeria maculans

Blackleg of rapeseed and canola (Brassica napus) is caused by various pathogenicity groups (PG) of Leptosphaeria maculans. The disease occurring in the Canadian prairies for the last two decades was caused by PG2 and was controlled by host resistance. PG3 and PG4 isolates have been found recently in Canada, but there is no resistance available against these pathogenicity groups in commercial Canadian varieties. This study sought to identify canola cultivars that could be used as sources of resistance to PG3 and to develop molecular markers for marker-assisted selection. Resistance to PG3 specifically was found in B. napus ‘Dunkeld’ and ‘Quinta’, while B. juncea ‘Cutlass’ and ‘Domo’ proved to be resistant to PG2, PG3, and PG4. A set of F2 progeny of ‘Westar’ (susceptible) × ‘Dunkeld’ was used to identify genetic markers linked to PG3 resistance. These markers were physically located on a BAC clone from B. rapa subsp. pekinensis containing a homolog to a serine threonine 20 (ste20)-like kinase in Arabidopsis thaliana. Thus, we have developed a sequence characterized amplified region (SCAR) marker available for marker-assisted selection in breeding canola for resistance against blackleg caused by L. maculans PG3. This work has received a provisional patent (serial # 60/977,933 – Oct. 5, 2007).

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Importance of spatio–temporal connectivity to maintain species experiencing range shifts

Ecography ◽

10.1111/ecog.04716 ◽

2020 ◽

Vol 43 (4) ◽

pp. 591-603 ◽

Cited By ~ 3

Author(s):

Jun‐Long Huang ◽

Marco Andrello ◽

Alexandre Camargo Martensen ◽

Santiago Saura ◽

Dian‐Feng Liu ◽

...

Keyword(s):

Range Shifts ◽

Temporal Connectivity ◽

Spatio Temporal

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Historical amphibian declines and extinctions in Brazil linked to chytridiomycosis

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2016.2254 ◽

2017 ◽

Vol 284 (1848) ◽

pp. 20162254 ◽

Cited By ~ 40

Author(s):

Tamilie Carvalho ◽

C. Guilherme Becker ◽

Luís Felipe Toledo

Keyword(s):

Host Resistance ◽

Batrachochytrium Dendrobatidis ◽

Amphibian Declines ◽

Temporal Association ◽

Population Declines ◽

Amphibian Population ◽

Spatio Temporal ◽

High Diversity ◽

Potential Origin ◽

Temporal Overlap

The recent increase in emerging fungal diseases is causing unprecedented threats to biodiversity. The origin of spread of the frog-killing fungus Batrachochytrium dendrobatidis ( Bd ) is a matter of continued debate. To date, the historical amphibian declines in Brazil could not be attributed to chytridiomycosis; the high diversity of hosts coupled with the presence of several Bd lineages predating the reported declines raised the hypothesis that a hypervirulent Bd genotype spread from Brazil to other continents causing the recent global amphibian crisis. We tested for a spatio-temporal overlap between Bd and areas of historical amphibian population declines and extinctions in Brazil. A spatio-temporal convergence between Bd and declines would support the hypothesis that Brazilian amphibians were not adapted to Bd prior to the reported declines, thus weakening the hypothesis that Brazil was the global origin of Bd emergence. Alternatively, a lack of spatio-temporal association between Bd and frog declines would indicate an evolution of host resistance in Brazilian frogs predating Bd 's global emergence , further supporting Brazil as the potential origin of the Bd panzootic. Here, we Bd -screened over 30 000 museum-preserved tadpoles collected in Brazil between 1930 and 2015 and overlaid spatio-temporal Bd data with areas of historical amphibian declines. We detected an increase in the proportion of Bd -infected tadpoles during the peak of amphibian declines (1979–1987). We also found that clusters of Bd -positive samples spatio-temporally overlapped with most records of amphibian declines in Brazil's Atlantic Forest. Our findings indicate that Brazil is post epizootic for chytridiomycosis and provide another piece to the puzzle to explain the origin of Bd globally.

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