Diverse phytoplasmas associated with maize bushy stunt disease in Peru

Delia Gamarra Gamarra,Assunta Bertaccini,Charo Milagros Villar,Walter Darlyn Ingaruca Esteban,Nicoletta Contaldo,Emerson Clovis Carrasco Lozano,Gilberto Torres Suarez

doi:10.1007/s10658-022-02470-5

Delia Gamarra Gamarra, Assunta Bertaccini + Show 5 more

Open Access

https://doi.org/10.1007/s10658-022-02470-5

Copy DOI

Abstract

Corn plants showing symptoms of midribs chlorosis, and leaf reddening, short internodes, ear proliferation, and plant growth reduction were collected in Peru from fields in nine localities in the provinces of Huancayo, Chupaca, and Jauja in the Junín region, and tested to verify phytoplasma presence and identity. Primers amplifying the phytoplasma ribosomal 16S and ribosomal protein genes were used. The phytoplasma presence was detected in symptomatic samples from all the surveyed areas. The sequencing of the obtained amplicons indicated the presence of ‘Candidatus Phytoplasma asteris’ and ‘Ca. P. pruni’-related strains. A BLASTn search of sequenced genes showed that the two ‘Candidatus Phytoplasma’ strains identified in corn shares 100% and 99.82% identity with the ‘Ca. P. asteris’ strains from maize and 99.92% and 99.55% with ‘Ca. P. pruni’-related strains, respectively. The RFLP analyses allowed to enclose these phytoplasma strains in the 16SrI-B and 16SrIII-J subgroups; however, the two phytoplasmas were, in some cases, present in mixed infection. The 16SrIII-J phytoplasma is for the first time reported associated with the maize bushy stunt disease and this represent a relevant information for the disease epidemiology towards its appropriate management in the affected area.

Highlights

Corn is one of the main species cultivated worldwide (FAO, 2020)
The restriction fragment length polymorphism (RFLP) and virtual RFLP analyses of these samples with appropriate restriction enzymes (MseI = Tru1I, and HhaI) on the amplicons and the sequences obtained with the phytoplasma primer pairs R16F2n/R2 and 3fwr/3rev, respectively, showed the presence of two profiles and allowed enclosing the detected phytoplasmas in subgroups 16SrI-B and 16SrIII-J (Figs. 4 and 5)
The BLASTn analysis showed that these sequences, except the one submitted to GenBank under the accession number MW578363, had a 100% identity to those of Maize bushy stunt (MBS) phytoplasma strains from Colombia, Brazil, and Mexico (GenBank accession numbers HQ530152, CP015149, and AY265208 respectively) and to several other ‘Ca. P. asteris’-related strains

Summary

Introduction

Corn is one of the main species cultivated worldwide (FAO, 2020). In Peru, both hard yellow and starchy corns are grown for human consumption as dry or wet grain (Huamanchumo de la Cuba, 2013). The MBS infected corn plants shows symptoms of midribs chlorosis, and leaf reddening, short internodes, ear proliferation, and plant growth reduction (Bedendo et al, 1997). This disease was reported associated with the presence of ‘Candidatus Phytoplasma asteris’ (16SrI-B subgroup) (Lee et al, 2004) and known to be transmitted by Dalbulus maidis (Hemiptera: Cicadellidae) (Nault & Delong, 1980). Phytoplasmas are pleomorphic bacteria with size ranging from 200 to 800 nm They multiply and survive in isotonic environments including plant phloem and hemolymph of insect vectors (Bertaccini et al, 2014) and are classified using molecular tools such as nested polymerase chain reaction (PCR) on the 16S ribosomal gene followed by sequencing or restriction fragment length polymorphism (RFLP) analyses. The two methods are defining ‘Candidatus Phytoplasma’ species and 16S ribosomal groups, respectively (Bertaccini & Lee, 2018; IRPCM, 2004)

Methods

Results

Conclusion