Genetic variation and genome-environment association of alfalfa (Medicago sativa L.) populations under long-term grazing
Notice bibliographique
Résumé
Alfalfa (Medicago sativa. L) is the most valuable forage legume for the beef, dairy, and forage industries in Canada with approximately 4 million hectares of alfalfa and alfalfa-grass mixtures in Western Canada. Alfalfa forage production has been limited by low stand persistence due to the negative impacts of environmental factors and continuous grazing. The objectives of this study were: 1) to identify the phenotypic and genetic diversities of alfalfa populations collected from long-term grazing sites across four soil zones of Saskatchewan; 2) to compare genetic structure of the populations from long-term grazing sites to commercial alfalfa cultivars released between 1926 and 1980; 3) to identify the SNP markers linked to morphological traits and nutritive values; and 4) to detect SNP markers associated with environmental factors associated with plant persistence at long-term grazing sites. This study collected alfalfa populations across four soil zones of Saskatchewan representing 14 alfalfa stands with minimum 25 years of grazing history. The seven agro-morphological and three nutritive value traits of the 14 alfalfa populations from long-term grazing were evaluated in a replicated field trial using a nested randomized complete block design (RCBD). The genotyping-by-sequencing (GBS) reads were aligned to the Medicago sativa reference genome and 19,853 high-quality SNPs were generated. The STRUCTURE analysis identified that the alfalfa populations from long-term grazing sites were the hybrid cross from subspecies Medicago sativa subsp. sativa (hereafter M. sativa) and M. falcata. Plants from the Black soil zone produced the highest forage dry matter yield, plant height, and stem number, while the lowest values for these traits were recorded plants from the Brown soil zone. This was because the alfalfa populations from the Black soil zone had maintained more of the M. sativa genome over long-term grazing, while the alfalfa populations from the Brown soil zone maintained more of the M. falcata genome. The genotype-environment association (GEA) identified 70 SNPs for the alfalfa populations with grazing history including summer extreme temperature (22 SNPs), growing season precipitation (15 SNPs), soil nutrient (30 SNPs), and soil pH (3 SNPs). Fifty-three candidate genes were significantly associated with eight environmental factors, which were mainly involved in plant resistances to biotic and abiotic stresses, such as heat, drought, salt and diseases. The genome-wide-association-study (GWAS) analysis identified nine SNPs associated with stem number and nutritive value on the Medicago sativa reference genome. Once validated, these markers and candidate genes identified in the study would be useful for developing markers for marker-assisted selection to improve alfalfa cultivars with enhanced tolerance to long-term grazing and environmental stresses in Western Canada.
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Comment cette classification a été obtenuedéplier
Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,001 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,003 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule tête enseignante, pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».