植原体引起雪花木小叶病在中国的首次报道

2022年首次在广州市发现园林植物雪花木小叶病病株, 采用分子生物学技术对其进行植原体的种类鉴定。以雪花木叶片总DNA为模板, 利用植原体16S rRNA通用引物P1/P7进行PCR扩增, 获得广东雪花木小叶病植原体(BLL-GD2022)16S rRNA基因片段(1 811 bp, GenBank登录号为OQ625536)。16S rRNA序列相似性显示, BLL-GD2022与16SrVI组植原体株系的相似性最高, 为97.05%~99.83%, 其中与隶属于16SrVI-D亚组的10个植原体株系相似性为99.21%~99.83%。系统进化分析显示, BLL-GD2022与16SrVI组各植原体株系聚类在一个大分支, 其中与16SrVI-D亚组成员聚类在一个小分支, 亲缘关系最近。基于16S rRNA序列的iPhyClassifier限制性内切酶虚拟RFLP分析表明, BLL-GD2022与16SrVI-D亚组的参考株系Brinjal little leaf phytoplasma (GenBank登录号为X83431)的酶切图谱一致, 相似系数为1.00。基于上述研究结果, 明确广州市雪花木小叶病植原体隶属16SrVI-D亚组成员。本研究首次在园林植物雪花木上检测到植原体, 通过16S rRNA序列分析明确为16SrVI-D亚组成员, 为开展16SrVI-D亚组植原体在蔬菜、花卉和园林植物的发生监测及病害防控提供科学依据。

First report of little leaf disease caused by phytoplasma on Breynia disticha in China

In 2022, the garden plant Breynia disticha exhibiting little leaf symptom was firstly observed in Guangzhou. The related phytoplasma was identified using molecular technology. The 16S rRNA fragment (1 811 bp, GenBank accession no.OQ625536) of phytoplasma associated with Breynia disticha little leaf disease in Guangdong province (BLL-GD2022) was amplified from total DNA of diseased plants using universal primers P1/P7. Sequence similarity analysis based on 16S rRNA sequence showed that BLL-GD2022 shared the higher similarity with 16SrVI group phytoplasma strains, which was 97.05%-99.83%, and the highest similarity (99.21% to 99.83%) with 10 phytoplasma strains belonging to the 16SrVI-D subgroup. Phylogenetic analyses showed that BLL-GD2022 clustered with the 16SrVI group phytoplasmas in a large branch and with the 16SrVI-D subgroup phytoplasmas in a small branch. This result revealed that BLL-GD2022 had the closest genetic relationship to the 16SrVI-D subgroup phytoplasmas. Based on the 16S rRNA sequence, virtual restriction fragment length polymorphism analysis using iPhyClassifier revealed that BLL-GD2022 and the reference strain Brinjal little leaf phytoplasma (GenBank Registration no.X83431) of the 16S rVI-D subgroup were consistent, with a similarity coefficient of 1.00. Based on the above results, the phytoplasma of Breynia disticha little leaf disease in Guangzhou is a strain of 16SrVI-D subgroup. Phytoplasma was detected firstly on the garden plant B.disticha, and BLL-GD2022 was identified to belong to the 16SrVI-D subgroup. The result provides scientific basis for monitoring the occurrence and disease prevention and control of 16SrVI-D subgroup phytoplasma in vegetables, flowers and garden plants.