2023 年 37 巻 p. 1-11
Growth and development, and polar auxin transport in epicotyls of etiolated pea (Pisum sativum L. cv Alaska) seedlings grown under hypergravity conditions produced by centrifugation were studied. Seeds were allowed to germinate and grow under various magnitude of hypergravity conditions for 3.5 days in the dark. Hypergravity at up to 50 G had little effect on epicotyl elongation growth, but increasing gravity force up to 300 G resulted in a reduction of elongation growth, the reduction at 100 G and 200 G being ca. 30% and 50% of control, respectively. Although expressions of genes playing an important role in polar auxin transport, auxin efflux carrier PsPINs and influx carrier PsAUX1, were not affected by hypergravity conditions, polar auxin transport activities of the epicotyls were substantially reduced, those at 100 G and 200 G being ca. 80% and 60% of control, respectively. In addition, close relationships between inhibition of elongation growth and polar auxin transport of the epicotyls were observed. These results suggest that hypergravity-regulated polar auxin activity is involved in inhibition of elongation growth of epicotyls of etiolated pea seedlings. The mechanisms to regulate elongation growth and polar auxin transport are discussed.
