Landicho Darwin Magsino, Montañez Ray Jerome Mojica, Camagna Maurizio, Neang Sokty, Bulasag Abriel Salaria, Magdaraog Peter Magan, Sato Ikuo, Takemoto Daigo, Maejima Kensaku, Pinili Marita Sanfuego, Chiba Sotaro
Central Laboratory, National Plant Quarantine Services Division, Bureau of Plant Industry, Manila 1004, Philippines.
Nagoya University Asian Satellite Campuses Institute, Philippine Campus, University of the Philippines Los Baños, Laguna 4031, Philippines.
Biology (Basel). 2024 Jul 15;13(7):522. doi: 10.3390/biology13070522.
Cassava witches' broom disease (CWBD) is one of the most devastating diseases of cassava ( Crantz), and it threatens global production of the crop. In 2017, a phytoplasma, Phytoplasma luffae ( P. luffae), was reported in the Philippines, and it has been considered as the causal agent, despite unknown etiology and transmission of CWBD. In this study, the nationwide occurrence of CWBD was assessed, and detection of CWBD's pathogen was attempted using polymerase chain reaction (PCR) and next-generation sequencing (NGS) techniques. The results showed that CWBD has spread and become severe, exhibiting symptoms such as small leaf proliferation, shortened internodes, and vascular necrosis. PCR analysis revealed a low phytoplasma detection rate, possibly due to low titer, uneven distribution, or absence in the CWBD-symptomatic cassava. In addition, NGS techniques confirm the PCR results, revealing the absence or extremely low phytoplasma read counts, but a surprisingly high abundance of fastidious and xylem-limited fungus, sp. in CWBD-symptomatic plants. These findings cast doubt over the involvement of phytoplasma in CWBD and instead highlight the potential association of sp strongly supporting the recent findings in mainland Southeast Asia. Further investigations are needed to verify the etiology of CWBD and identify infection mechanisms of sp. to develop effective diagnostic and control methods for disease management.
木薯丛枝病（CWBD）是木薯（Crantz）最具毁灭性的病害之一，威胁着全球木薯产量。2017年，菲律宾报道了一种植原体，丝瓜植原体（P. luffae），尽管木薯丛枝病的病因和传播方式尚不清楚，但它被认为是致病因子。在本研究中，评估了木薯丛枝病在全国范围内的发生情况，并尝试使用聚合酶链反应（PCR）和下一代测序（NGS）技术检测木薯丛枝病的病原体。结果表明，木薯丛枝病已经传播并变得严重，表现出小叶增生、节间缩短和维管束坏死等症状。PCR分析显示植原体检测率较低，可能是由于木薯丛枝病症状明显的木薯中滴度低、分布不均或不存在。此外，NGS技术证实了PCR结果，显示植原体读数缺失或极低，但在木薯丛枝病症状明显的植物中，一种苛求的、局限于木质部的真菌的丰度惊人地高。这些发现对植原体与木薯丛枝病的关联提出了质疑，反而突出了该真菌与木薯丛枝病的潜在关联，有力地支持了东南亚大陆最近的研究结果。需要进一步调查以核实木薯丛枝病的病因，并确定该真菌的感染机制，从而开发有效的诊断和控制方法以进行病害管理。
