Sugarcane Grassy Shoot (SCGS) disease is known to be related to Rice Yellow Dwarf (RYD) phytoplasmas (16SrXI-B group) which are found predominantly in sugarcane growing areas of the Indian subcontinent and South-East Asia. The 16S rRNA gene sequences of SCGS phytoplasma strains belonging to the 16SrXI-B group share 98.07 % similarity with ‘Ca. Phytoplasma cynodontis’ strain BGWL-C1 followed by 97.65 % similarity with ‘Ca. P. oryzae’ strain RYD-J. Being placed distinctly away from both the phylogenetically related species, the taxonomic identity of SCGS phytoplasma is unclear and confusing. We attempted to resolve the phylogenetic positions of SCGS phytoplasma based on the phylogenetic analysis of 16S rRNA gene (>1500 bp), nine housekeeping genes (>3500 aa), core genome phylogeny (>10 000 aa) and OGRI values. The draft genome sequences of SCGS phytoplasma (strain SCGS) and Bermuda Grass White leaf (BGWL) phytoplasma (strain LW01), closely related to ‘Ca. P. cynodontis’, were obtained. The SCGS genome was comprised of 29 scaffolds corresponding to 505 173 bp while LW01 assembly contained 21 scaffolds corresponding to 483 935 bp with the fold coverages over 330× and completeness over 90 % for both the genomes. The G+C content of SCGS was 19.86 % while that of LW01 was 20.46 %. The orthoANI values for the strain SCGS against strains LW01 was 79.42 %, and dDDH values were 22. Overall analysis reveals that SCGS phytoplasma forms a distant clade in RYD group of phytoplasmas. Based on phylogenetic analyses and OGRI values obtained from the genome sequences, a novel taxon ‘Candidatus Phytoplasma sacchari’ is proposed.

A novel e-waste-degrading strain, PE08T, was isolated from contaminated soil collected from a paper mill yard in Lalkuan, Uttarakhand, India. Strain PE08T was Gram-stain-negative, rod-shaped, aerobic, oxidase-positive and catalase-positive. Optimum growth was observed at 30 °C (range, 5–40 °C), with 1–2 % NaCl (range, 0–3 %) and at pH 7 (range 6–11). The phylogeny based on 16S rRNA gene sequences delineated strain PE08T to the genus Pseudomonas and showed highest sequence similarity to Pseudomonas furukawaii KF707T (98.70 %), followed by Pseudomonas aeruginosa DSM 50071T (98.62 %) and Pseudomonas resinovorans DSM 21078T (97.93 %). The genome of strain PE08T was sequenced and had one scaffold of 6056953 bp, 99.84 % completeness and 182× coverage were obtained. The G+C content in the genome was 64.24 mol%. The DNA–DNA hybridization and average nucleotide identity values between strain PE08T and its closely related type strain, P. resinovorans DSM 21078T were below 34.8 % and 87.96 %, respectively. The phylogenetic analysis based on whole-genome sequence and concatenated GyrB and RpoB proteins revealed that strain PE08T forms a district clade in the family Pseudomonadaceae . The predominant fatty acids were summed feature 8 (C18 :  1ω7c and/or C18 :1 ω6c), summed feature 3 (C16 :  1ω7c and/or C16 :  1ω6c), C16 : 0 and C12 : 0. The major polar lipids were diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine. The phenotypic, chemotaxonomic and genetic analysis, including overall genome relatedness index values, indicated that strain PE08T represents a novel species of the genus Pseudomonas , for which the name Pseudomonas lalkuanensis sp. nov. is proposed. The type strain is PE08T (=MCC 3792=KCTC 72454=CCUG 73691).

We performed whole-genome sequencing of two phytoplasmas associated with sugarcane grassy shoot (SCGS) and Bermuda grass white leaf diseases. These are the first draft genomes of SCGS phytoplasma (strain SCGS) and ‘Candidatus Phytoplasma cynodontis’ (strain LW01) and may help to delineate these phytoplasmas at a finer taxonomic level.

Phytoplasma taxonomy has been a topic of discussion for the last two and half decades. Since the Japanese scientists discovered the phytoplasma bodies in 1967, the phytoplasma taxonomy was limited to disease symptomology for a long time. The advances in DNA-based markers and sequencing improved phytoplasma classification. In 2004, the International Research Programme on Comparative Mycoplasmology (IRPCM)- Phytoplasma/Spiroplasma Working Team – Phytoplasma taxonomy group provided the description of the provisional genus ‘Candidatus Phytoplasma’ with guidelines to describe the new provisional phytoplasma species. The unintentional consequences of these guidelines led to the description of many phytoplasma species where species characterization was restricted to a partial sequence of the 16S rRNA gene alone. Additionally, the lack of a complete set of housekeeping gene sequences or genome sequences, as well as the heterogeneity among closely related phytoplasmas limited the development of a comprehensive Multi-Locus Sequence Typing (MLST) system. To address these issues, researchers tried deducing the definition of phytoplasma species using phytoplasmas genome sequences and the average nucleotide identity (ANI). In another attempts, a new phytoplasma species were described based on the Overall Genome relatedness Values (OGRI) values fetched from the genome sequences. These studies align with the attempts to standardize the classification and nomenclature of ‘Candidatus’ bacteria. With a brief historical account of phytoplasma taxonomy and recent developments, this review highlights the current issues and provides recommendations for a comprehensive system for phytoplasma taxonomy until phytoplasma retains ‘Candidatus’ status.

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