Santosa, Adyatma Irawan

Mungbean yellow mosaic India virus (MYMIV, Begomovirus vignaradiataindiaense, Genus Begomovirus) is well understood to incite chlorosis on mung bean (Vigna radiata) and yard long bean (V. unguiculata ssp. sesquipedalis). However, presence of the virus in mung bean in Indonesia has not been studied. Furthermore, leaf deformation symptoms, typical of phytoplasma disease, are also observed occasionally on both horticultural species. On February 2025, two yard long bean and two mung bean samples showing chlorosis, mosaic, and small leaf as well as non-symptomatic yard long bean and mung bean, one sample respectively, were collected in Nganjuk Regency, East Java Province. The samples were tested by PCR using Krusty/Homer and SPG1/SPG2 universal primers for begomoviruses, and the nested R16mF2/R16mR2 and R16F2n/R16R2 universal primers for phytoplasmas detection. One mung bean (no. 119) and one yard long bean (no. 419) were shown to be mixed-infected by begomovirus and phytoplasma. One mung bean (no. 219) was positive for phytoplasma only. One yard long bean (no. 519) and both non-symptomatic samples (no. 319 and 619) were negative for both pathogens. BLAST and phylogenetic analyses demonstrated that both begomovirus isolates are MYMIV, and the three phytoplasma strains are associated with the ‘Candidatus Phytoplasma aurantifolia’ (16SrII-A group, peanut witches'-broom). This research reported the first occurrences of MYMIV in mung bean and mixed infection of MYMIV and phytoplasma in mung bean and yard long bean in Indonesia, to the best of our knowledge. Further surveys are necessary to study both pathogens distribution among legumes in the country.

Tobacco (Nicotiana tabacum) is among the agricultural products with the highest added value in Turkey. Although frequently associated with its negative effects on human health, it also provides important contributions to the Turkish economy with the employment it creates in rural areas and continues to be a strategic product. Many postgraduate theses and studies related to the sociological and economic importance of the production of this plant, which is of great importance for our country, have been carried out. However, there are very limited studies on plant diseases in tobacco production areas in Turkey. Phytoplasma is one of the important plant pathogens that cause yield loss in tobacco. Since available data on phytoplasma diseases on tobacco was very scarce worldwide, field surveys to collect samples showing phytoplasma infection-like symptoms such as yellowish color changes, leaf blisters, proliferation, dwarfism, and other physical abnormalities were carried out in Çanakkale and Balıkesir provinces of Turkey from June to August 2021. The presence of phytoplasmas in six samples was confirmed by 16S ribosomal DNA amplification by nested-PCR using universal phytoplasma primer sets, which also suggested the pathogen associated with the symptoms on tobacco. According to phylogenetic study and virtual-RFLP analysis using AluI and MseI endonuclease enzymes, the six Turkish tobacco phytoplasma strains all belong to group 16SrXII and have more than 99% nucleotide sequence identity with some members of ‘Candidatus Phytoplasma solani’ of the taxonomic subgroup ‘stolbur’ (16SrXII-A). Genetic distances analysis indicated that group 16SrI was more closely related to 16SrXII than 16SrVI, in agreement with the groups clustering in the phylogenetic tree. Neutrality tests found that 16SrI and 16SrXII groups are experiencing expanding or bottleneck selections, probably due to new mutations in the 16S rRNA gene fragment. Meanwhile, 16SrVI populations are shown to be undergoing balancing selections, indicating that its isolates have evolved for a long time.