Inhibition of ethylene biosynthesis by antisense ACC oxidase RNA prevents chilling injury in Charentais cantaloupe melons

Non-freezing low temperature storage causes injury to melons and most other fruit and vegetables of tropical and subtropical origin. We demonstrate here that ethylene suppression through an antisense ACC oxidase (ACO) gene considerably reduced the sensitivity of Charentais cantaloupe melons to chilling injury. In contrast to wild-type fruit, antisense ACO melons did not develop the characteristic chilling injury of pitting and browning of the rind neither when stored at low temperature (3 weeks at 2 °C) nor upon rewarming. Treating antisense melons with 10 p.p.m. ethylene for more than 1 d prior to cold storage resulted in the restoration of chilling sensitivity. When the ethylene treatment was performed after cold storage, the chilling injury symptoms did not appear. The tolerance to chilling was associated with a lower accumulation of ethanol and acetaldehyde, reduced membrane deterioration and higher capacity of the fruit to remove active oxygen species. The activities of catalase, superoxide dismutase and peroxidase were markedly increased in antisense ACO fruit in comparison with wild-type fruit, particulary upon rewarming and post-storage ethylene treatment. Severe chilling injury symptoms were correlated with a lower activity of activated oxygen scavenging enzymes. These results demonstrate that ethylene acts in conjunction with low temperature to induce metabolic shifts that participate in the development of chilling injury.     

瓜类果斑病菌的检测与防治进展

瓜类果斑病菌可引起西瓜、甜瓜等葫芦科植物患病,可通过种子远距离传播,是一种常见的瓜类采后果实腐烂的病原菌。该病害具有发病迅速、传播速度快等特点,一旦感染会对瓜类产量带来巨大损失,因而田间病菌的检测与诊断及早期预防十分重要。本文系统地综述了国内外瓜类果斑病菌的免疫学检测方法、分子生物学检测方法及防治等研究进展。     

Trap catches of the sweetpotato whitefly （Homoptera： Aleyrodidae） in the Imperial Valley, California, from 1996 to 2002

An outbreak of the sweetpotato whitefly, Bemisia tabaci （Gennadius）, biotype B occurred in the Imperial Valley, California in 1991. The insects destroyed melon crops and seriously damaged other vegetables, ornamentals and row crops. As a result of the need for sampling technology, we developed a whitefly trap （named the CC trap） that could be left in the field for extended time periods. We used the traps to monitor populations ofB. tabaci adults during year-round samplings from 1996 to 2002 to study variations in the weekly trap catches of the insect. The greatest number ofB. tabaci adults was recorded in 1996, followed by a continuing annual decrease in trap catches each year through 2002. The overall decline of B. tabaci is attributed in part to the adoption of an integrated pest management （IPM） program initiated in 1992 and reduced melon hectares from 1996 to 2002. Other factors may also have contributed to the population reductions. Seasonally, B. tabaci trap catches decreased during the late summer and fall concurrent with decreasing minimum tempera- tares that are suggested to be a significant factor affecting seasonal activity and reproduction.