Abstract
Arctic alpine species follow a mixed clonal-sexual reproductive strategy based on the environmental conditions at flowering. Here, we explored the natural variation for adventitious root formation among genotypes of the alpine perennial Arabis alpina that show differences in flowering habit. We scored the presence of adventitious roots on the hypocotyl, main stem and axillary branches on plants growing in a long-day greenhouse. We also assessed natural variation for adventitious rooting in response to foliar auxin spray. In both experimental approaches, we did not detect a correlation between adventitious rooting and flowering habit. In the greenhouse, and without the application of synthetic auxin, the accession Wca showed higher propensity to produce adventitious roots on the main stem compared to the other accessions. The transcript accumulation of the A. alpina homologue of the auxin inducible GH3.3 gene (AaGH3.3) on stems correlated with the adventitious rooting phenotype of Wca. Synthetic auxin, 1-Naphthaleneacetic acid (1-NAA), enhanced the number of plants with adventitious roots on the main stem and axillary branches. A. alpina plants showed an age-, dosage- and genotype-dependent response to 1-NAA. Among the genotypes tested, the accession Dor was insensitive to auxin and Wca responded to auxin on axillary branches.
Highlights
Arctic and alpine environments are characterized by low temperatures, strong desiccating winds, rocky soils with unstable substrates and short and unpredictable growing seasons that limit plant growth
These results suggest that A. alpina accessions show natural variation in adventitious rooting and that AaGH3.3 expression correlates with higher competence in adventitious rooting in the West Carpathians (Wca) accession
A. alpina plants develop adventitious roots on axillary branches, which can sustain the clonal growth of the plant through the formation of daughter ramets in natural populations [12,25]
Summary
Arctic and alpine environments are characterized by low temperatures, strong desiccating winds, rocky soils with unstable substrates and short and unpredictable growing seasons that limit plant growth. To distribute risk and survive in severe habitats at high altitudes, many alpine species reproduce through seeds, and clonally [1,3]. In this respect, the vast majority of the alpine species are perennials and can bypass sexual reproduction in years when seed production is unreliable [4,5]. Many perennial relatives of A. thaliana, propagate clonally through stolons (e.g., in Arabidopsis halleri) and rhizomes (e.g., in Arabidopsis lyrata) in parallel to their self-incompatible mating system [7]
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