Exploring The Heterosis For Salt Tolerance Of Root System Growth In Arabidopsis

Heterosis describes a phenomenon in which hybrid offspring exhibits phenotypic performance superior to that of their parents with divergent genetic background. The phenomenon has been successfully applied in the agricultural production over 100 years, whereas the underlying mechanism is still obscure. Most researches on heterosis were mainly focused on the heterotic performance of biomass and yield in crop hybrids. Many studies in rice and maize have investigated the transcriptomic and epigenomic variations in hybrids and their the potential role in heterosis. Some studies have explored the heterosis for resistance in Arabidopsis, for example heterosis for cold tolerance, drought tolerance and bacterial resistance. However, research on heterosis for salt tolerance was rarely reported. In this project, using Arabidopsis thaliana as a model system, we screened the hybrid combinations in which hybrids shows increased tolerance to salt stress compared to their parents, and explored preliminarily their underlying molecular mechanisms.Firstly, we investigated the root length(a quantitative parameter to evaluate salt tolerance) of hybrids and their parents from 61 hybrid combinations in Arabidopsis thaliana under the condition of 0 m M(control) and 100 m M Na Cl treatment. As a result, 9 hybrids showing heterosis for salt tolerance were identified, of which Col × Er-0 and Col × Rag1-1 exhibited the most significant heterotic phenotype.Further, we performed GWAS analysis of MPH(Mid-Parent Heterosis) and BPH(Best-Parent Heterosis) of root length in Arabidopsis hybrids with and without salt treatment(100 m M Na Cl). We found that several kinds of transcription factors are associated with MPH of root length in hybrids under no salt stress, of which AT5G38450 may contributes to the heterosis for root growth through the cytokinin synthesis pathway. Whereas some kinds of kinases are associated with BPH of root length in hybrids under salt treatment, of which AT1G16300 is candidate genes of heterosis for salt tolerance.In summary, this research explored preliminarily the heterosis for salt tolerance in Arabidopsis, and provides useful clues and resources to dissect fully the molecular mechanisms of salt stress response and heterosis for salt tolerance in Arabidopsis.