RESUMEN
Improving the salt stress tolerance of crops is an important goal in plant breeding. Changes in the number of chromosome sets (i.e. ploidy level) cause genome dosage effects which can result in enhanced or novel traits. Maternal inheritance versus paternal inheritance of the same chromosome sets can have differential epigenetic effects on traits of F1 offspring. Hence, genome dosage effects can be parent-of-origin independent or dependent. The model plant Arabidopsis thaliana displays both genome dosage and parent-of-origin effects on plant growth under non-stress conditions. Using an isogenic ploidy series of diploid, triploid and tetraploid lines, we investigate the extent of genome dosage effects and their parent-of-origin dependency on in vitro salt stress tolerance of seedlings across 10 different A. thaliana accessions (genetic backgrounds). We detected genome dosage effects on salt stress tolerance for tetraploid lines in five accessions. In addition, through the generation of isogenic reciprocal F1 triploid lines, both parent-of-origin dependent and independent genome dosage effects on salt stress tolerance were detected. Thus, our results indicate not only that genome dosage balance effects can have significant impacts on abiotic stress tolerance in A. thaliana but also that parent-of-origin specific genome dosage effects can affect salt stress tolerance in plants.
RESUMEN
Climate change impacts on food security will involve negative impacts on crop yields, and potentially on the nutritional quality of staple crops. Common bean is the most important grain legume staple crop for human diets and nutrition worldwide. We demonstrate by crop modeling that the majority of current common bean growing areas in southeastern Africa will become unsuitable for bean cultivation by the year 2050. We further demonstrate reductions in yields of available common bean varieties in a field trial that is a climate analogue site for future predicted drought conditions. Little is known regarding the impact of climate change induced abiotic stresses on the nutritional quality of common beans. Our analysis of nutritional and antinutritional compounds reveals that iron levels in common bean grains are reduced under future climate-scenario relevant drought stress conditions. In contrast, the levels of protein, zinc, lead and phytic acid increase in the beans under such drought stress conditions. This indicates that under climate-change induced drought scenarios, future bean servings by 2050 will likely have lower nutritional quality, posing challenges for ongoing climate-proofing of bean production for yields, nutritional quality, human health, and food security.
RESUMEN
BACKGROUND: The phenomenon of heterosis is critical to plant breeding and agricultural productivity. Heterosis occurs when F1 hybrid offspring display quantitative improvements in traits to levels that do not occur in the parents. Increasing the genome dosage (i.e. ploidy level) of F1 offspring can contribute to heterosis effects. Sugar beet (Beta vulgaris) provides a model for investigating the relative effects of genetic hybridity and genome dosage on heterosis. Sugar beet lines of different ploidy levels were crossed to generate diploid and triploid F1 offspring to investigate the effect of; (1) paternal genome dosage increase on F1 heterosis, and; (2) homozygous versus heterozygous tetraploid male parents on F1 triploid heterosis. A range of traits of agronomic and commercial importance were analyzed for the extent of heterosis effects observed in the F1 offspring. RESULTS: Comparisons of parental lines to diploid (EA, EB) and triploid (EAA, EBB) F1 hybrids for total yield, root yield, and sugar yield indicated that there was no effect of paternal genome dosage increases on heterosis levels, indicating that hybridity is the main contributor to the heterosis levels observed. For all traits measured (apart from seed viability), F1 triploid hybrids derived from heterozygous tetraploid male parents displayed equivalent levels of heterosis as F1 triploid hybrids generated with homozygous tetraploid male parents, suggesting that heterosis gains in F1 triploids do not arise by simply increasing the extent of multi-locus heterozygosity in sugar beet F1 offspring. CONCLUSIONS: Overall, our study indicates that; (1) increasing the paternal genome dosage does not enhance heterosis in F1 hybrids, and; (2) increasing multi-locus heterozygosity using highly heterozygous paternal genomes to generate F1 triploid hybrids does not enhance heterosis. Our findings have implications for the design of future F1 hybrid improvement programs for sugar beet.
