TobpreproHypSys-A gene expression and defense protein activity in the tobacco wounding response

Tobacco hydroxyproline-rich glycopeptide systemin precursor A (TobpreproHypSys-A), from which TobHypSys Ⅰ and Ⅱ are released, plays a crucial role in defense responses. Here, we investigated the expression of TobpreproHypSys-A and the activity of defense proteins in tobacco organs during wounding. Expression was induced more rapidly in upper, non-wounded leaves than in lower, wounded leaves. At 24 h after mechanical wounding, expression was low in the roots, but increased in the stems and flowers, although to a lesser extent than in the leaves. At 3 or 10 d after insect-wounding, expression did not differ among organs, suggesting that TobpreproHypSys-A could be induced globally and continuously throughout such stress. During that period, the activity of two defense proteins -- PPO and PI -- was consistent with the expression of TobpreproHypSys-A in various organs. This indicates that those proteins also could be regulated by TobHypSys, both globally and continuously.