帝王大丽花初始外植体褐变影响因素及控制措施研究

Effects of Factors and Control Measures on Browningof Initial Explants in Dahlia imperialis

针对帝王大丽花在组织培养时出现的初始外植体严重褐变问题,从取材部位、空气暴露时间、水插通氧和温度4个方面分析褐变发生的原因。结果表明,帝王大丽花枝条上部节位褐变程度高于下部节位,其中多酚氧化酶活性和苯丙氨酸解氨酶活性及总酚含量从枝条上端到下端逐渐降低,变化趋势与褐变程度呈现一致性;增加空气暴露时间、枝条水插通氧和高温下取样均可加剧褐变程度。分别采取不同环境下切割、接种前进行不同时间水插和低温处理、接种后进行不同时间黑暗和低温处理等褐变控制措施,结果表明,与空气中正常切割相比,在1.0%维生素C溶液中切割外植体褐变程度可减轻4.08%;枝条水插5 d+4℃低温处理5 h后接种的外植体褐变程度比空白对照降低17.12%,且茎段外植体幼芽萌发和生长正常;对接种外植体进行7 d的暗处理+同时4℃低温处理6 d,外植体褐变程度比对照降低31.25%,且茎段外植体幼芽萌发正常,叶片浓绿,长势健壮。

In this study,severe browning of initial explants in Dahlia imperialis during tissue culture was analyzed from four aspects:sampling position,air exposure time,water oxygen penetration,and temperature.The results showed that the activity of PPO and PAL and content of total phenol decreased with the decrease of sampling position of shoot initial explants in the whole plant,resulting in decreased browing.Browning was found to be more severe when sampling at longer air exposure time,higher water oxygen penetration,or higher temperature.The measures for inhibiting browning were further studied,including sampling under different environments,water insertion at different processing time,low temperature treatment before inoculation,and dark treatment and low temperature treatment after inoculation.Compared with normal cutting in air,explants cutting in 1.0%vitamin C solutionreduced the browning rate by 4.08%.The browning rate of the inoculated explants pretreated with five days of water inserting and low temperature at 4℃for five hours was 17.12%lower than that in blank control,and the germination and growth of explants were normal.Dark treatment for seven days and low temperature at 4℃for six days resulted in a 31.25%reduction in browing rate compared to the control,with the explants germinating and growing normally with dark green leaves.