Abstract
Abstract Black root rot, caused by two Berkeleyomyces species ( B. basicola and B. rouxiae ), is a major disease of lettuce ( Lactuca sativa L.) in tropical areas. Nationwide surveys in Brazil indicated similar levels of incidence as well as an overlapping geographical distribution of B. basicola and B. rouxiae across major lettuce-producing areas. The most promising strategy for managing these polyphagous and aggressive pathogens is the deployment of genetic resistance. The heirloom cultivar ‘La Brillante’ displayed resistance to a broad range of isolates of both Berkeleyomyces species. However, to date, there is no information about the genetic control of B. basicola and B. rouxiae . Inheritance studies investigating the resistance of ‘La Brillante’ to isolates of both pathogens were conducted separately employing F 2 populations derived from crosses with the highly susceptible cultivar ‘Elisa’. The hybrid origin of individual F 1 plants was assessed via RAPD marker genotyping. Two bona-fide F 1 plants were then selfed to obtain two independent F 2 segregating populations. The contrasting parental cultivars and F 2 seedlings were then separately inoculated with B. rouxiae (F 2 population size = 247) and B. basicola (F 2 population size = 166). Chi-square test was employed to assess the goodness of fit of the observed segregation patterns against each pathogen to the predicted Mendelian ratios. All ‘Elisa’ plants displayed highly susceptible reactions to both pathogens, whereas all ‘La Brillante’ plants were resistant even under harsh inoculation conditions, indicating high levels of penetrance of this trait. The F 2 populations inoculated with either B. basicola or B. rouxiae displayed a good fit to 3:1 resistant/susceptible segregation ratios, indicating monogenic and dominant resistance to both pathogens. Additional experiments are necessary to verify whether the same gene/locus or distinct genes/loci are controlling the resistance to B. rouxiae and B. basicola . Nevertheless, this simple monogenic inheritance will facilitate the incorporation of these resistant traits into elite lettuce breeding lines and cultivars.
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Claims 5
Claim · model-written summary
All plants of the susceptible cultivar Elisa showed highly susceptible reactions to both Berkeleyomyces pathogens after inoculation.
- Taxon
- lettuce
Lactuca sativat0 - Material
- Elisae0
- Outcome
- highly susceptible reactionse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“All ‘Elisa’ plants displayed highly susceptible reactions to both pathogens”
t0“lettuce”
Claim · model-written summary
All La Brillante plants were resistant to both pathogens even under harsh inoculation conditions, indicating high penetrance of the trait.
- Taxon
- lettuceLactuca sativat0
- Material
- La Brillantee0
- Outcome
- resistante0
- Qualifier
- harsh inoculation conditionse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“all ‘La Brillante’ plants were resistant even under harsh inoculation conditions”
t0“lettuce”
Claim · model-written summary
The F2 population inoculated with B. rouxiae fit a 3:1 resistant/susceptible segregation ratio, indicating monogenic dominant resistance.
- Taxon
- lettuceLactuca sativat0
- Interactor
- B. rouxiaeBerkeleyomyces rouxiaee0pathogen
- Outcome
- 3:1 resistant/susceptible segregation ratiose0
- Value
- 3:1e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The F 2 populations inoculated with either B. basicola or B. rouxiae displayed a good fit to 3:1 resistant/susceptible segregation ratios, indicating monogenic and dominant resistance to both pathogens”
t0“lettuce”
Claim · model-written summary
The F2 population inoculated with B. basicola fit a 3:1 resistant/susceptible segregation ratio, indicating monogenic dominant resistance.
- Taxon
- lettuceLactuca sativat0
- Interactor
- B. basicola
Berkeleyomyces basicolae0pathogen - Outcome
- 3:1 resistant/susceptible segregation ratiose0
- Value
- 3:1e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The F 2 populations inoculated with either B. basicola or B. rouxiae displayed a good fit to 3:1 resistant/susceptible segregation ratios, indicating monogenic and dominant resistance to both pathogens”
t0“lettuce”
Claim · model-written summary
Nationwide surveys in Brazil indicated similar incidence and overlapping geographical distribution of B. basicola and B. rouxiae across major lettuce-producing areas.
- Taxon
- lettuceLactuca sativat0
- Interactor
- B. basicolaBerkeleyomyces basicolae0pathogen
- Second interactor
- B. rouxiaeBerkeleyomyces rouxiaee0pathogen
- Outcome
- similar levels of incidencee0
- Setting
- Brazile0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Nationwide surveys in Brazil indicated similar levels of incidence as well as an overlapping geographical distribution of B. basicola and B. rouxiae across major lettuce-producing areas”
t0“lettuce”