Characterization of the inaA gene and expression of ice nucleation phenotype in Pantoea ananatis isolates from Maize White Spot disease

Abstract

ABSTRACT. Maize White Spot (MWS), a foliar disease caused by Pantoea ananatis, could cause up to 60% yield loss. Some strains of P. ananatis harboring the ice nucleation gene inaA catalyze the formation of ice nuclei, causing tissue damage at temperatures slightly below freezing. Little is known about the relationship between the presence of the ina gene in this maize pathogen and its expression during the phenomenon of ice nucleus formation. Here, we attempted to verify the presence of the inaA gene and the expression of phenotype in vitro. The identity of the isolates and the presence of the inaA gene were determined by P. ananatis speciesspecific primers. The expression of the inaA gene was assessed in vitro by the visualization of ice-crystal formation in water at subzero temperatures. A total of ninety P. ananatis isolates from MWS lesions were characterized. The presence of the inaA gene was confirmed by gel electrophoresis of the 350-400-bp PCR products. The inaA primers did not lead to DNA fragment amplification in three isolates. The ice nucleation phenotype was expressed in 83.34% of the isolates carrying the inaA gene. Our study showed that the ice nucleation in P. ananatis isolated from MWS lesions was dependent on the presence of a functional ina gene in the genome. We also found evidence indicating that some P. ananatis strains have a mutated form of the inaA gene, producing a non-functional ice nucleation protein. This is the first report on inaA gene characterization in P. ananatis isolates from Maize White Spot.

Pantoea ananatis: genomic insights into a versatile pathogen

“…However, orthologues of other predicted pathogenicity determinants (Fig. ), such as flagella and fimbriae biosynthetic proteins, non‐fimbrial adhesins, amylovoran/stewartan‐like exopolysaccharide and potential cell wall‐degrading enzymes (CWDEs), are encoded on the genomes of many P. ananatis strains (De Maayer et al ., ; Ma et al ., ; Miller et al ., ). Recent genetic and mutagenic analyses have also contributed to our understanding of the mechanisms underlying P. ananatis phytopathogenesis.…”

Update of the list of QPS‐recommended biological agents intentionally added to food or feed as notified to EFSA 11: suitability of taxonomic units notified to EFSA until September 2019

“…P. ananatis is a phytopathogen that infects a wide range of crop and forest plants such as maize (Miller et al, 2016), rice (Watanabe et al, 1996), onion (Gitaitis et al, 2002;Weller-Stuart et al, 2014), eucalyptus (Coutinho et al, 2002;De Maayer et al, 2010) and it has occasionally been reported as a clinical isolate infecting workers with plant material or from immunocompromised individuals in hospital settings. The number of reports linking the TU with human disease is scarce (De Baere et al, 2004;De Maayer et al, 2012;Manoharan et al, 2012).…”

Functional display of ice nucleation protein InaZ on the surface of bacterial ghosts

“…7,8 Generally, ina C bacteria are Gram-negative, epiphytic and pathogenic as Pseudomonas syringae, Pseudomonas putidia, Erwinia herbicola, Erwinia ananas, Xanthomonas campestris, or Pantoea ananatis among others. [7][8][9][10][11][12][13][14][15][16][17] The well characterized plant pathogen Pseudomonas syringae represents one of the most efficient INA bacterial ice nucleus known, initiating plant damaging ice formation at temperatures of ¡2 C. 11,18 Aside from the habitat of an epiphytic plant pathogen, Pseudomonas syringae, as well as other INA bacteria were found in clouds, rain, snow and streams indicating that they are disseminated with the earth hydrological cycle. [19][20][21][22] Airborne ice-active bacteria are involved in cloud condensation -acting as cloud condensation nuclei (CCN) -and precipitation.…”