人工接种CGMMV后与西瓜倒瓤相关部分生理指标的研究

 本研究以辽宁省田间主栽西瓜品种“京欣”为试材,通过测定多聚半乳糖醛酸酶(PG)的活性,以及乙烯、丙酮酸及丙酮酸代谢产物—乳酸、乙醛、乙醇含量的变化,明确了西瓜感染黄瓜绿斑驳花叶病毒后上述生理指标的改变与西瓜倒瓤的关系。研究结果表明:接种处理的西瓜果实授粉后7 d和28 d PG出现2次活性高峰,PG活性过高将导致果肉软化;乙烯含量亦在授粉后21~28 d明显高于健康对照,这一变化将导致果肉水渍化败坏;无论接种早晚,西瓜果实内丙酮酸及丙酮酸代谢产物均有不同程度的积累。定植期接种处理的西瓜,授粉后21 d时西瓜果实内丙酮酸含量为健康对照的2.51倍,35 d时达健康对照4.09倍;授粉后7 d乳酸含量已显著高于对照,35 d时接种处理的西瓜果实内的乳酸含量迅速增加至43.5 μmol·g^-1FW,达健康对照的4.7倍;乙醛含量随着西瓜成熟逐渐增加,尤其是授粉后21~35 d乙醛含量增加速度极为迅速,35 d时达健康对照的26.4倍;乙醇含量授粉后7 d最高,达健康对照的10.1倍,随后有所下降。于压蔓期接种处理的西瓜果实,授粉后21 d,丙酮酸、乳酸、乙醛含量明显高于健康对照,但均低于定植期接种处理的,乙醇含量与健康对照无明显差异,也就是说,感染该病毒越早,对西瓜的生长影响越明显。

Physiological responses of watermelon infected by Cucumber green mottle mosaic virus

Studies were conducted with watermelon cultivar (Jing Xin) in Liaoning Province. In order to reveal the physiological mechanism of blood flesh after watermelon inoculated by Cucumber green mottle mosaic virus (CGMMV), physiological and biochemical indexes such as activity of polygalacturonase (PG) and contents of ethylene, pyruvate, lactic acid, acetaldehyde and alcohol in watermelon pulp were studied. The results indicated that the activity of PG and the content of ethylene were apparently increased, compared with that of the control before the matured, over-riped and water-soaked pulp were infected by CGMMV. No matter the inoculation was early or late, the contents of pyruvate, lactic acid, acetaldehyde and alcohol in infected watermelon pulp displayed different levels of accumulation. When the watermelons were inoculated by CGMMV at the pruning stage, the contents of pyruvic acid, lactic acid, acetaldehyde in the pulp were significantly higher than those of the control at 21 d after pollination, but lower than those in the CGMMV-infected watermelon pulp inoculated at the planting stage. The content of ethanol had no significant difference in the CGMMV-infected and healthy control pulp. The test showed that the earlier the watermelons infected with CGMMV, the more severely the growth was influenced. The concentration of pyruvate in the infected pulp accumulated to 2.51- and 4.09-folds compared with that of the control at the 21^th and 35^th day after pollination, respectively. The concentration of lactic acid in the infected pulp was much higher and up to 43.5 μmol·g^-1FW (4.7-folds higher than that of the control) at the 35^th day post inoculation. In conclusion, the accumulating with lactic acid would lead to acidification and deterioration in pulp. Acetaldehyde increased significantly during the period of at 21 to 35 days after pollination. The high content of acetaldehyde caused serious damage to watermelon, meanwhile it was harmful for body health. In a word, after inoculation with CGMMV, the changes of above physiological and biochemical indexes influenced the watermelon quality, which led to a great loss of watermelon edibility.