Abstract
Heterosis is important for agriculture; however, little is known about the mechanisms driving hybrid vigor. Ultimately, heterosis depends on the interactions of specific alleles and epialleles provided by the parents, which is why hybrids can exhibit different levels of heterosis, even within the same species. We characterize the development of several intraspecific Arabidopsis (Arabidopsis thaliana) F1 hybrids that show different levels of heterosis at maturity. We identify several phases of heterosis beginning during embryogenesis and culminating in a final phase of vegetative maturity and seed production. During each phase, the hybrids show different levels and patterns of growth, despite the close relatedness of the parents. For instance, during the vegetative phases, the hybrids develop larger leaves than the parents to varied extents, and they do so by exploiting increases in cell size and cell numbers in different ratios. Consistent with this finding, we observed changes in the expression of genes known to regulate leaf size in developing rosettes of the hybrids, with the patterns of altered expression differing between combinations. The data show that heterosis is dependent on changes in development throughout the growth cycle of the hybrid, with the traits of mature vegetative biomass and reproductive yield as cumulative outcomes of heterosis at different levels, tissues, and times of development.
Highlights
Heterosis is important for agriculture; little is known about the mechanisms driving hybrid vigor
Important traits, such as vegetative biomass or seed yield, generally need to exceed the better parent value (BPV) for the hybrid to be considered commercially beneficial. These mature traits are comprised of smaller component traits that may only exceed the average performance of the two parents but collectively result in BPV for important traits
Traits exceeding MPV and BPV are categorized as exhibiting midparent heterosis (MPH) and better parent heterosis (BPH), respectively
Summary
Heterosis is important for agriculture; little is known about the mechanisms driving hybrid vigor. Heterosis depends on the interactions of specific alleles and epialleles provided by the parents, which is why hybrids can exhibit different levels of heterosis, even within the same species. The data show that heterosis is dependent on changes in development throughout the growth cycle of the hybrid, with the traits of mature vegetative biomass and reproductive yield as cumulative outcomes of heterosis at different levels, tissues, and times of development. The levels of growth and heterosis attained by a given hybrid combination depend on the interactions of the specific alleles and epialleles contributed by the parents This is consistent with hybrid vigor being the cumulative outcome of different levels of heterosis in different tissues at different times of development (for review, see Schnable and Springer, 2013). It is feasible to carry out these various omic studies on many different tissue and cell types at different stages of development across a variety of hybrids
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have