Responses to Short-term Low Night Temperature of Sucrose-metabolizing in Domesticated Tomato and Wild Relative

Chilling-sensitive tomato(Solanum lycopersicon)'Money Maker'and chilling-tolerant wild tomato(S.habrochaites)'LA1777'were cultivated in phytotron,and effects of low night temperature of 15℃(control),9℃and 6℃and recovery on carbohydrate content and sucrose-metabolizing enzymes activities in tomato fruits were investigated.The results showed that fructose and glucose levels increased in chilling-tolerant wild tomato('LA1777')fruits after 0.5 d treatment at 6℃,while with no significant change in chilling-sensitive tomato('Money Maker')fruits.The sucrose and starch levels in'Money Maker'fruits decreased significantly at 6℃,but increased in'LA1777'.During the recovery period,the sucrose levels in two types tomato fruits both recovered to control level.The fructose and glucose contents in fruits after low night temperature-treatment could not recovered to the control level,except for 9℃.The invertase and sucrose synthase(SS hydrolysis direction)activities decreased in two types of tomatoes at 6℃,and could not recovery to the control level;However,the sucrose synthase synthesis direction and sucrose phosphate synthase(SPS)activities increased in chilling-sensitive tomato('Money Maker')fruits while with no significant change in chilling-tolerant wild tomat(o'LA1777').These results demonstrate that the chilling-tolerant tomato('LA1777')enhances higher level of total carbohydrate content to acclimate chilling stress under short-time low night temperature,while chilling-sensitive tomato responses to low temperature by decreasing it.