Abstract
AbstractOverwintering ability is an important selection criterion for Miscanthus breeding in temperate regions. Insufficient overwintering ability of the currently leading Miscanthus biomass cultivar, M. ×giganteus (M×g) ‘1993–1780', in regions where average annual minimum temperatures are −26.1°C (USDA hardiness zone 5) or lower poses a pressing need to develop new cultivars with superior cold tolerance. To facilitate breeding of Miscanthus, this study characterized phenotypic and genetic variation of overwintering ability in an M. sinensis germplasm panel consisting of 564 accessions, evaluated in field trials at three locations in North America and two in Asia. Genome‐wide association (GWA) and genomic prediction analyses were performed. The Korea/N China M. sinensis genetic group is a valuable gene pool for cold tolerance. The Yangtze‐Qinling, Southern Japan, and Northern Japan genetic groups were also potential sources of cold tolerance. A total of 73 marker–trait associations were detected for overwintering ability. Estimated breeding value for overwintering ability based on these 73 markers could explain 55% of the variation for first winter overwintering ability among M. sinensis. Average genomic prediction ability for overwintering ability across 50 fivefold cross‐validations was high (~0.73) after accounting for population structure. Common genomic regions for overwintering ability were detected by GWA analyses and a previous parallel QTL mapping study using three interconnected biparental F1 populations. One QTL on Miscanthus LG 8 encompassed five GWA hits and a known cold‐responsive gene, COR47. The other overwintering ability QTL on Miscanthus LG 11 contained two GWA hits and three known cold stress‐related genes, carboxylesterase 13 (CEX13), WRKY2 transcription factor, and cold shock domain (CSDP1). Miscanthus accessions collected from high latitude locations with cold winters had higher rates of overwintering, and more alleles for overwintering, than accessions collected from southern locations with mild winters.
Highlights
The perennial C4 grass Miscanthus is a promising bioenergy crop (Clifton‐Brown, Chiang, & Hodkinson, 2008; Clifton‐ Brown, Stampfl, & Jones, 2004; Głowacka et al, 2014,2015; Heaton, Dohleman, & Long, 2008; Heaton, Voigt, & Long, 2004; Somerville, Youngs, Taylor, Davis, & Long, 2010)
We studied the overwintering ability of 565 Miscanthus genotypes, including 561 M. sinensis, 3 closely related M. floridulus, and the M. ×giganteus (M×g) ‘1993–1780’ control
In the M. sinensis diversity panel, highly significant differences in overwintering ability were observed among genetic groups, genotypes within genetic groups, locations, year of establishment, number of growing seasons, and their interactions except for genetic group by year interaction (Table 2, Figures 2, 3, 4a)
Summary
The perennial C4 grass Miscanthus is a promising bioenergy crop (Clifton‐Brown, Chiang, & Hodkinson, 2008; Clifton‐ Brown, Stampfl, & Jones, 2004; Głowacka et al, 2014,2015; Heaton, Dohleman, & Long, 2008; Heaton, Voigt, & Long, 2004; Somerville, Youngs, Taylor, Davis, & Long, 2010). Only a single triploid clone of M×g, which is derived from the interspecific hybridization between Miscanthus sacchariflorus and M. sinensis, is available to US farmers (Głowacka et al, 2015; Hodkinson & Renvoize, 2001). Natural populations of Miscanthus are found from tropical and subtropical areas of East Asia and Oceania to ~50°N in eastern Russia (Clifton‐Brown et al, 2008; Sacks, Juvik, Lin, Stewart, & Yamada, 2013). Such a wide distribution of Miscanthus provides a genetically diverse and valuable gene pool from which to breed new cultivars, including those of M×g
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