QTL mapping of winter dormancy and associated traits in two switchgrass pseudo-F1 populations: lowland x lowland and lowland x upland

Rasyidah M Razar,Ali Missaoui

doi:10.1186/s12870-020-02714-8

Abstract

BackgroundSwitchgrass (Panicum virgatum) undergoes winter dormancy by sensing photoperiod and temperature changes. It transitions to winter dormancy in early fall following at the end of reproduction and exits dormancy in the spring. The duration of the growing season affects the accumulation of biomass and yield. In this study, we conducted QTL mapping of winter dormancy measured by fall regrowth height (FRH) and normalized difference vegetation index (NDVI), spring emergence (SE), and flowering date (FD) in two bi-parental pseudo-F1 populations derived from crosses between the lowland AP13 with the lowland B6 (AB) with 285 progenies, and the lowland B6 with the upland VS16 (BV) with 227 progenies.ResultsWe identified 18 QTLs for FRH, 18 QTLs for NDVI, 21 QTLs for SE, and 30 QTLs for FD. The percent variance explained by these QTLs ranged between 4.21–23.27% for FRH, 4.47–24.06% for NDVI, 4.35–32.77% for SE, and 4.61–29.74% for FD. A higher number of QTL was discovered in the BV population, suggesting more variants in the lowland x upland population contributing to the expression of seasonal dormancy underlying traits. We identified 9 regions of colocalized QTL with possible pleiotropic gene action. The positive correlation between FRH or NDVI with dry biomass weight suggests that winter dormancy duration could affect switchgrass biomass yield. The medium to high heritability levels of FRH (0.55–0.64 H2) and NDVI (0.30–0.61 H2) implies the possibility of using the traits for indirect selection for biomass yield.ConclusionMarkers found within the significant QTL interval can serve as genomic resources for breeding non-dormant and semi-dormant switchgrass cultivars for the southern regions, where growers can benefit from the longer production season.

Highlights

Switchgrass (Panicum virgatum) undergoes winter dormancy by sensing photoperiod and temperature changes
For fall regrowth height (FRH) and normalized difference vegetation index (NDVI) collected in fall 2018, both population distributions were skewed to the right, indicating lower population FRH and NDVI values
VG Genotypic variance; VGY Genotype by year variance; VE Error variance; H2 Broad-sense heritability; AThe first portion of B6 x VS16 population (BV) population that was planted in April 2017; BThe second portion of BV population that was planted in Significant quantitative trait loci (QTL) Using 2772 and 3766 SNP markers for AP13 x B6 (AB) and BV population, respectively, for QTL mapping, we identified 16, 14, 12, and 20 QTLs for FRH, NDVI, spring emergence (SE), and flowering date (FD), respectively, mapped in both populations and years using LS means (Supplementary Table 1–4)

Summary

Introduction

Switchgrass (Panicum virgatum) undergoes winter dormancy by sensing photoperiod and temperature changes. It transitions to winter dormancy in early fall following at the end of reproduction and exits dormancy in the spring. Switchgrass, Panicum virgatum L. is a C4 warm season grass native to most of North America, ranging from southern Canada to northern Mexico [1]. It is predominantly cross-pollinated due to gametophytic selfincompatibility [2]. Switchgrass uses include animal grazing, soil conservation, landscaping, and more recently as biofuel feedstock [1]. Its suitability for planting in marginal land unsuitable for row crops makes it the right species for biofuel [5]

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Discussion

Conclusion