Tuberous root thickening: A rapid response to hypoxia in sweetpotato (Ipomoea batatas (L.) Lam.)

Although it is known that tuberous root growth in sweetpotato (Ipomoea batatas (L.) Lam.) is strongly inhibited by O₂ deprivation, the time course of hypoxia-induced growth inhibition remains unclear. To study the growth pattern of the tuberous root, we measured the change in root diameter in response to hypoxia. The thickening rate of the tuberous root decreased to almost zero after 1 h of hypoxia treatment, and this strong growth-inhibition pattern was maintained during the 24-h hypoxia treatment period. After the treatment, the growth rate slowly returned to the normal value in approximately 10 h. Thus, tuberous root growth rapidly responded to the reduction in O ₂ concentration, and it reversibly recovered from short-term hypoxia-induced growth inhibition in half a day.