The synthesis of cytosolic ascorbate peroxidases in germinating seeds and seedlings of soybean and their behavior under flooding stress.

Cytosolic ascorbate peroxidases (cAPXs) of soybean have been found by proteome analysis to be downregulated in submerged seedlings. To elucidate the physiological meaning of this downregulation, soybean cAPXs were characterized in this study. Vigorous synthesis was detected in germinating seeds and seedlings. Expression of the corresponding genes was detected clearly in tissues that actively underwent cell division. The gene expression was suppressed by flooding stress, but not by salinity, cold or drought stress. The expression recovered 1 d after release from flooding stress, accompanied by growth resurgence.