Priming canola resistance to blackleg with weakly aggressive isolates leads to an activation of hydroxycinnamates
Bibliographic record
Abstract
Blackleg (Phoma leaf spot), caused by the ascomycete Leptosphaeria spp. (anamorph: Phoma lingam), is a serious yield-limiting factor in canola. Leptosphaeria spp. populations are highly diverse and display differential interactions with canola cultivars, ranging from hypersensitive-like reactions to partial resistance and susceptibility. Leptosphaeria biglobosa encompasses weakly aggressive isolates and can be found late in the season towards maturity stages of the crop while other isolates from Leptosphaeria maculans are highly aggressive and can be detected throughout the season. In an earlier study, we showed the primary involvement of lignin in the containment of the progress of Phoma leaf spot symptoms around the infection sites by comparing the reaction of three different cultivars with a set of isolates with various levels of aggressiveness. The present investigation reports on further characterization of the host responses to L. biglobosa and L. maculans isolates used individually or subsequently in the infection. Hydroxycinnamates were the major phenolics that differentially accumulated locally or systemically from the infection sites in response to either pre- or co-inoculation with the weakly aggressive isolate tested. Given the involvement of these hydroxycinnamates as precursors for the synthesis of lignin and phenylamide phytoalexins, their detected amounts in response to the priming with a weakly aggressive isolate could explain the restricted development of further inoculated highly aggressive isolates. Key words: canola, Leptosphaeria maculans, L. biglobosa, blackleg, phenolics, phenylamides, hydroxycinnamates, ferulates, phytoalexins. Le chancre noir (phoma), causé par l’ascomycète Leptosphaeria spp. (forme imparfaite : Phoma lingam), constitue un facteur limitant au rendement du canola. Les populations de Leptosphaeria spp. sont très diversifiées et montrent des interactions différentielles, variant de l’hypersensibilité à la résistance partielle ou la sensibilité, vis-à-vis des cultivars de canola. Leptosphaeria biglobosa se compose d’isolats peu agressifs qui n’apparaissent que tard dans la saison quand les plantes ont atteint leur maturité. Leptosphaeria maculans comporte des isolats très agressifs et peut être détecté durant toute la saison de production. Dans une étude précédente comparant les réactions différentielles de trois cultivars à une série d’isolats ayant des niveaux différents d’agressivité, nous avions montré le rôle de la lignine comme composante principale dans la restriction de la progression des symptômes de la maladie autour des sites d’infection. La présente étude fait davantage état de la caractérisation des réponses de l’hôte aux isolats de L. biglobosa et de L. maculans, inoculés soit séparément soit l’un après l’autre. Les dérivés hydroxycinnamiques sont les principaux composés phénoliques accumulés de manière différentielle, que ce soit localement autours des sites d’infection ou systémiquement, en réaction à la pré- ou à la co-inoculation avec l’isolat peu agressif étudié. Étant donné le rôle de ces dérivés hydroxycinnamiques comme précurseurs dans la synthèse de la lignine et de celle des phytoalexines de nature phénylamidique, les quantités induites en réaction à l’isolat peu agressif pourraient expliquer le taux relativement limité de symptômes causés par l’inoculation ultérieure d’isolats beaucoup plus agressifs. Mots-clés : canola, Leptosphaeria maculans, L. biglobosa, chancre noir, composés phénoliques, phénylamides, dérivés hydroxycinnamiques, dérivés féruliques, phytoalexines.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".