Natural variation in timing of stress-responsive gene expression predicts heterosis in intraspecific hybrids of Arabidopsis.

Marisa Miller, Qingxin Song, Xiaoli Shi, Thomas E Juenger, Z Jeffrey Chen

Nature communications 2015

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The genetic distance between hybridizing parents affects heterosis; however, the mechanisms for this remain unclear. Here we report that this genetic distance correlates with natural variation and epigenetic regulation of circadian clock-mediated stress responses. In intraspecific hybrids of Arabidopsis thaliana, genome-wide expression of many biotic and abiotic stress-responsive genes is diurnally repressed and this correlates with biomass heterosis and biomass quantitative trait loci. Expression differences of selected stress-responsive genes among diverse ecotypes are predictive of heterosis in their hybrids. Stress-responsive genes are repressed in the hybrids under normal conditions but are induced to mid-parent or higher levels under stress at certain times of the day, potentially balancing the tradeoff between stress responses and growth. Consistent with this hypothesis, repression of two candidate stress-responsive genes increases growth vigour. Our findings may therefore provide new criteria for effectively selecting parents to produce high- or low-yield hybrids.

Citation

Marisa Miller, Qingxin Song, Xiaoli Shi, Thomas E Juenger, Z Jeffrey Chen. Natural variation in timing of stress-responsive gene expression predicts heterosis in intraspecific hybrids of Arabidopsis. Nature communications. 2015;6:7453