Genetics of Flooding Tolerance in an F2 Miscanthus sacchariflorus ssp. lutarioriparius × M. sinensis Population

Abstract

Miscanthus is a warm-season, perennial grass cultivated as a feedstock for bioenergy and bioproducts. M. sacchariflorus ssp. lutarioriparius has high yield potential and is well-adapted to seasonal flooding, but little is known about the genetics of this adaptation. We conducted a quantitative trait locus (QTL) analysis on a population of 332 diploid Miscanthus ×giganteus (Mxg) F₂s derived from an initial cross between diploid M. sacchariflorus ssp. lutarioriparius ‘PF30022’ and diploid M. sinensis ‘PMS-014’, followed by intermating 50 F₁s. Using tanks in a greenhouse to assess the effects of partial submergence on actively growing plants, we compared an aerobic soil control to a 6-week flood treatment. The study's primary objectives were to (1) identify QTL for flooding tolerance in Miscanthus, (2) identify candidate genes and (3) compare ethylene response factors in Miscanthus with those in rice and Arabidopsis, sorghum and maize for binding site sequence homology and synteny, especially those associated with flooding tolerance. In total, 10 QTL and 66 candidate genes for partial submergence tolerance were identified (including many for ethylene signalling), a first report for Miscanthus. Notably, none of the Miscanthus candidates were orthologs of rice Sub1A, SK1 or SK2, yet the ‘PF30022’ parent exhibited a snorkeling phenotype, indicating convergent evolution. This study will facilitate breeding of climate-resiliant Mxg.