Buckwheat (Fagopyrum esculentum Moench) is a fast-growing, low-input crop in the Polygonaceae family, cultivated on about 2 million hectares worldwide, mainly in Russia, China, and Ukraine by FAO (2023). In Taiwan, it is grown as a winter cover crop during fallow periods and is valued for improving soil health, suppressing weeds, and supporting sustainable farming systems. It is also utilized in various food products due to its rich fiber content and gluten-free properties. In May 2024, 147 out of 3000 plants (Taichung No. 5) corresponding to an incidence rate of approximately 5% exhibiting floral abnormalities, including phyllody, virescence, and flower sterility, were observed in Xinshe District in Taichung, central Taiwan (Fig. 1). These symptoms were indicative of possible phytoplasma infection. For further investigation, floral and leaf tissues were randomly collected from 10 symptomatic and 10 asymptomatic buckwheat plants. Plant total DNA was extracted using the DNeasy Plant Mini Kit, and PCR was performed targeting the 16S rRNA gene using universal phytoplasma primers P1A/P7A, followed by a semi-nested reaction with P1A/16S-SR (Lee et al. 2004). All PCR amplicons of approximately 1.5 kb were obtained only from symptomatic samples. PCR amplicons were sequenced by Sanger sequencing, and sequences were assembled by BioEdit. All symptomatic samples yielded identical sequences and a representative sequence (1,543 bp, nearly full-length 16S rRNA gene) was deposited in GenBank (Accession no. PV487329). Based on virtual RFLP analysis using iPhyClassifier (Zhao et al. 2009), the phytoplasma strain detected in diseased buckwheat plants was identified as a ‘Candidatus Phytoplasma aurantifolia/citri’-related strain, sharing 98.27% sequence identity with the reference strain (witches broom disease of lime, WBDL, Accession no. U15442). The strain, designated as Buckwheat Phyllody (BWP) TSIPS 3-1, was classified within the 16SrII-A subgroup, with a similarity coefficient of 1.00 when compared to the reference strain of subgroup 16SrII-A (Accession no. L33765). A BLASTn search against the NCBI database revealed that BWP-TSIPS 3-1 shared 99.94% identity with the 16S rRNA gene of potato purple top phytoplasma (Accession no. KM212951, a ‘Ca. P. aurantifolia/citri’-related strain), identified in Guangdong, China (Cheng et al. 2019). To further confirm phytoplasma identity, an additional gene marker, secY gene was amplified by semi-nested PCR using group-specific primers SecYF1(II)/SecYR1(II) and SecYF2(II) /SecYR1(II) (Lee et al. 2010). The 1,263-bp amplicons were obtained from all symptomatic samples. Sequencing results revealed identical secY sequences across samples, and a representative sequence was deposited in GenBank (Accession no. PV567544). BLASTn analysis indicated 100% (1263/1263) identity with the secY gene of the phytoplasmas, including black gram witches’-broom phytoplasma in Myanmar (Accession no. AB703249), which is classified within the 16SrII-A subgroup (Win and Jung, 2012). Phytoplasma infections associated with buckwheat have been rarely reported, with only a single case documented in India, though the short 16S rRNA gene sequence limited subgroup classification (Bandakkanavar et al. 2023). Similar symptoms, such as phyllody, have also been observed in Ukraine, but the causal agent remains unconfirmed due to the absence of molecular diagnostics (Demchenko et al. 2016). Our study confirmed the first identification of a ‘Ca. P. aurantifolia/citri’-related strain (16SrII-A subgroup) in buckwheat in Taiwan. Phytoplasmas of the 16SrII-A subgroup have been widely documented across Taiwan, including in Taichung (Tseng et al. 2012). Given the rising popularity of buckwheat for its dietary benefits and its increasing incorporation into crop rotation systems, especially as a winter cover crop, the presence of phytoplasma presents potential concerns. Infected buckwheat plants may inadvertently serve as hosts or reservoirs for phytoplasmas and their insect vectors, indicating a need for ongoing monitoring, especially in areas where buckwheat is part of crop rotations.