A SNP-Based Linkage Map and QTL Identification for Resistance to Yam Anthracnose Disease (YAD) in Water Yam (Dioscorea alata)

Abstract Background: Yam anthracnose disease (YAD) caused by Colletotrichum gloeosporioides is the primary cause of yield loss in water yam (Dioscorea alata), the widely cultivated species of yam. Development of resistant cultivars have been a prime target for sustainable management of anthracnose in water yam. Molecular breeding tools are required to expedite the development of improved yam varieties. QTL analysis using high density genetic maps serve as a powerful tool to discover key locations of quantitave traits. This study aimed at tagging quantitative trait loci (QTL) for anthracnose disease resistance in a bi-parental mapping population of D. alata.Results: In this study, two contrasting parents for yam anthracnose disease reaction and their 204 full- sib offspring were used to develop a high-density genetic linkage map with 3,257 SNP markers by the GBS technique. The total length of the consensus map was 1460.94 cM with an average of 163 markers per chromosome. Four QTLs were detected for anthracnose disease resistance in 4 locations on 3 chromosomes. The proportion of phenotypic variance explained by these QTLs ranged from 10 to 13%. Plant defense response genes including GDSL-like Lipase/Acylhydrolase, Protein kinase domain and F-box protein were also detected within the QTL regions. Conclusion: The results from the present study provide valuable insight into the genetic architecture of anthracnose resistance in water yam. The candidate markers and putative genes identified herewith form a relevant resource to apply marker-assisted selection as alternative to a conventional labor-intensive screening for anthracnose resistance in water yam.