Abstract
SummaryEpigenetic variation has been associated with a wide range of adaptive phenotypes in plants, but there exist few direct means for exploiting this variation. RNAi suppression of the plant‐specific gene, MutS HOMOLOG1 (MSH1), in multiple plant species produces a range of developmental changes accompanied by modulation of defence, phytohormone and abiotic stress response pathways along with methylome repatterning. This msh1‐conditioned developmental reprogramming is retained independent of transgene segregation, giving rise to transgene‐null ‘memory’ effects. An isogenic memory line crossed to wild type produces progeny families displaying increased variation in adaptive traits that respond to selection. This study investigates amenability of the MSH1 system for inducing agronomically valuable epigenetic variation in soybean. We developed MSH1 epi‐populations by crossing with msh1‐acquired soybean memory lines. Derived soybean epi‐lines showed increase in variance for multiple yield‐related traits including pods per plant, seed weight and maturity time in both glasshouse and field trials. Selected epi‐F2:4 and epi‐F2:5 lines showed an increase in seed yield over wild type. By epi‐F2:6, we observed a return of MSH1‐derived enhanced growth back to wild‐type levels. Epi‐populations also showed evidence of reduced epitype‐by‐environment (e × E) interaction, indicating higher yield stability. Transcript profiling of epi‐lines identified putative signatures of enhanced growth behaviour across generations. Genes related to cell cycle, abscisic acid biosynthesis and auxin response, particularly SMALL AUXIN UP RNAs (SAURs), were differentially expressed in epi‐F2:4 lines that showed increased yield when compared to epi‐F2:6. These data support the potential of MSH1‐derived epigenetic variation in plant breeding for enhanced yield and yield stability.
Highlights
Plants respond to changing environments through phenotypic plasticity that derives from both genetic and epigenetic factors (Bossdorf et al, 2010; Kooke et al, 2015)
MutS HOMOLOG1 (MSH1) suppression in soybean induces a characteristic pleiotropic phenotype that persists after transgene segregation
Affected plants grow slower than wild type (Figure 1b) and show delayed flowering, extended juvenility and enhanced branching
Summary
Plants respond to changing environments through phenotypic plasticity that derives from both genetic and epigenetic factors (Bossdorf et al, 2010; Kooke et al, 2015). Arabidopsis epigenetic recombinant inbred lines (epiRILs), derived from crossing wild-type Col-0 with met or ddm DNA methylation mutants, show segregation and heritability of novel methylation patterns together with phenotypic diversity (Johannes et al, 2009; Reinders et al, 2009; Roux et al, 2011). Recursive selection on epigenetic features of energy use efficiency showed higher yield potential and inheritance of acquired methylation patterns and agronomic characteristics (Hauben et al, 2009). These observations advance the hypothesis that induced epigenetic variation can be exploited effectively for selection in crop improvement
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