Cassava (Manihot esculenta Crantz) is widely grown in the Philippines mainly for human consumption, animal feed, and industrial purposes. However, the cassava industry is recently challenged by the cassava witches' broom (CWB) disease which is known to be caused by phytoplasmas. The extent of the disease and the causal phytoplasma strain in the country are not known until this study. Surveys in major cassava areas in the Philippines conducted from 2017 to 2019 revealed that CWB is present in 13 out of 19 provinces assessed in this study, with symptoms ranging from leaf proliferation, little leaf, shortened internodes, stunted growth, discoloration of the vascular system, and small tubers. Molecular detection (through nested PCR) and sequence analysis of phytoplasma 16S ribosomal RNA gene from CWB-infected plants showed high genetic similarity of >98.65% to Candidatus Phytoplasma luffae 16SrVIII. In addition, the 18 phytoplasma isolates from five provinces successfully grouped to Ca. Phytoplasma luffae 16SrVIII clade in the constructed phylogenetic tree. Analysis on the genetic diversity and structure of Ca. Phytoplasma luffae 16SrVIII sequences from cassava and other host plant species revealed low genetic diversity indices and a rudimentary genetic structure with high haplotype diversity. Meanwhile, neutrality tests showed evidence of recent population expansion in Ca. Phytoplasma luffae 16SrVIII. This is the first study to identify ‘Ca. Phytoplasma luffae’-related strain (16SrVIII) as the causal pathogen of CWB in the Philippines. The information generated in this study can help in better understanding the etiology of the disease and in formulating proper and effective strategies to detect and manage the disease in the Philippines.

木薯 ( Manihot esculenta Crantz) 在菲律宾广泛种植，主要用于人类消费、动物饲料和工业用途。然而，木薯产业最近受到已知由植原体引起的木薯金雀花 (CWB) 病的挑战。在这项研究之前，该国的疾病范围和致病植原体菌株尚不清楚。2017 年至 2019 年在菲律宾主要木薯产区进行的调查显示，在本研究评估的 19 个省份中，有 13 个省份存在 CWB，症状包括叶片增生、叶片少、节间缩短、生长发育迟缓、维管系统变色和小块茎。植原体16S的分子检测（通过巢式PCR）和序列分析来自 CWB 感染植物的核糖体 RNA 基因与Candidatus Phytoplasma luffae 16SrVIII 具有 > 98.65% 的高遗传相似性。此外，来自5个省份的18株植原体分离物成功归类到Ca。构建的系统发育树中的丝瓜植原体 16SrVIII 进化枝。Ca的遗传多样性和结构分析。来自木薯和其他寄主植物物种的丝瓜植原体 16SrVIII 序列揭示了低遗传多样性指数和具有高单倍型多样性的基本遗传结构。同时，中性测试显示了Ca最近人口扩张的证据。丝瓜植原体 16SrVIII。这是第一项识别“ Ca”的研究。丝瓜植原体相关菌株 (16SrVIII) 作为菲律宾 CWB 的致病病原体。本研究中产生的信息有助于更好地了解疾病的病因，并制定适当有效的策略来检测和管理菲律宾的疾病。