Quantitative trait loci and candidate genes for physico-chemical traits related to tuber quality in greater yam (Dioscorea alata L)
Arnau, Gemma | Desfontaines, Lucienne | Ehounou, Adou Emmanuel | Marie-Magdeleine, Carine | Kouakou, Amani Michel | Leinster, Jocelyne | Nudol, Elie | Maledon, Erick | Chaïr, Hanâ
BACKGROUND: Starch, dry matter content (DMC), proteins and sugars are among the major constituents of yam tuber quality. Genetic improvement programs need simple, rapid and low-cost tools to screen large populations. The objectives of this work were, through a quantitative trait loci mapping approach (QTL) on two diploid full-sib segregating populations: (1) to acquire knowledge on the genetic control of these traits; (2) to identify markers linked to the genomic regions controlling each trait, useful for marker-assisted selection (MAS); (3) to validate the QTLs on a diversity panel; and (4) to identify candidate genes from the validated QTLs. RESULTS: Heritabilities for all traits were moderately high to high. Significant correlations were observed between traits. A total of 25 QTLs were identified, including six for DMC, six for sugars, six for proteins, and seven for starch. The phenotypic variance explained by individual QTLs ranged from 14.3% to 28.6%. Majority of QTLs were validated on diversity panel, showing that they are not specific to the genetic background of the progenitors. The approximate physical location of validated QTLs allowed the identification of candidate genes for all studied traits. Those detected for starch content were mainly enzymes involved in starch and sucrose metabolism, while those detected for sugars were mainly involved in respiration and glycolysis. CONCLUSION: The validated QTLs will be useful for breeding programs using MAS to improve the quality of yam tubers. The putative genes should be useful in providing a better understanding of the physiological and molecular basis of these important tuber quality traits.
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