Isolation and identification of pathogenic bacteria causing cut chrysan-themum receptacle browning and screening of antibacterial agents(切花菊花心褐化病原菌分离鉴定及抑菌药剂筛选)

Abstract

Receptacle browning issues arise during the storage and transportation of cut chrysanthemums, leading to a decline in both ornamental and commercial values. Given the recurring nature of this issue in batches, it is hypothesized to be caused by pathogenic bacteria infection. To investigate the causes of this problem and find solutions, we analyzed the receptacle browning phenotype in ‘Jinshan’ summer chrysanthemums, isolated and identified the pathogenic bacteria following Koch’s postulates, determined the species through whole-genome sequencing analysis, screened high-efficiency inhibitors through agar plate inhibition assays, and validated their efficacy using cut chrysanthemum treatment experiments. The results indicated that receptacle browning led to an annual loss of approximately 10% in summer chrysanthemum production. The identified pathogenic bacterium was Bacillus altitudinis, which optimally grew at pH=7.0 and 42 ℃. Among the 15 commonly used ecofriendly and low-toxicity antibacterial agents evaluated, 80% ethylicin emerged as the most effective, with a 1 000-time dilution significantly inhibiting receptacle browning in two other chrysanthemum cultivars. In conclusion, this study successfully isolates and identifies the pathogenic bacteria responsible for receptacle browning in cut chrysanthemums, and screens ecofriendly, low-toxicity, and high-efficiency antibacterial agents, thereby providing a theoretical basis and technical support for addressing receptacle browning issues in cut chrysanthemums. . 切花菊在采后储运过程中面临花心褐化问题，严重影响了切花的观赏价值和商品价值。由于该问题成批次暴发，推测为病原菌感染所致。为探究该问题成因并寻找解决方案，本研究对夏菊‘金扇’花心褐化现象进行了观察分析，采用科赫（Koch）法则分离鉴定病原菌，借助全基因组测序分析确定病原菌种类，并通过平板抑菌试验和鲜切花处理试验筛选鉴定高效抑制剂。结果显示：花心褐化导致夏菊生产每年损失约10%；病原菌为高地芽孢杆菌（Bacillus altitudinis），其最适生长条件为pH=7.0和42 ℃。在评价的15种常用绿色低毒杀菌药剂中，80%乙蒜素为最优杀菌剂，其1 000倍稀释液可显著抑制其他2个品种菊花的花心褐化。综上所述，本研究成功分离鉴定了导致切花菊花心褐化问题的病原菌，并筛选到绿色、低毒且高效的抑菌药剂，为防治切花菊采后花心褐化问题提供了理论依据和技术支撑。

Keywords

• 切花菊(cut chrysanthemum)
• 花心褐化(receptacle browning)
• 病原菌分离鉴定(isolation and identification of pathogenic bacteria)
• 抑菌药剂筛选(screening of antibacterial agents)
• 乙蒜素(ethylicin)