Both epiphytic and endophytic strains of Rhodococcus fascians influence transporter gene expression and cytokinins in infected Pisum sativum L. seedlings

0489587 - ÚEB 2019 RIV NL eng J - Journal Article
Dhandapani, P. - Song, J. - Novák, Ondřej - Jameson, P. E.
Both epiphytic and endophytic strains of Rhodococcus fascians influence transporter gene expression and cytokinins in infected Pisum sativum L. seedlings.
Plant Growth Regulation. Roč. 85, č. 2 (2018), s. 231-242. ISSN 0167-6903. E-ISSN 1573-5087
R&D Projects: GA ČR(CZ) GA17-06613S
Institutional support: RVO:61389030
Keywords : Amino acid transporter * Cell wall invertase * Cytokinin * Pea * Rhodococcus fascians * Sucrose transporter * Sugar Will Eventually be Exported Transporter (SWEET)
OECD category: Plant sciences, botany
Impact factor: 2.473, year: 2018

Some strains of the soil bacterium Rhodococcus fascians maintain an epiphytic life style while others become endophytic. Virulent, endophytic strains cause multiple shoot growth and inhibit root growth of seed-inoculated Pisum sativum L. We were interested in assessing, at the molecular level, the impact of strains of contrasting niche on the emerging shoots and roots of inoculated seeds. The presence of R. fascians was monitored microscopically, endogenous cytokinin and chlorophyll levels were measured, and the expression of genes monitored by RT-qPCR. The expression of the pea sugar transporter genes (SWEET and SUT), amino acid (AAP) transporters and cell wall invertase gene family members, as well as expression of plant and bacterial cytokinin biosynthesis (IPT), activation (LOG) and degradation (CKX) genes were monitored. Both the virulent strain and the epiphytic strain affected the expression of the transporter genes, with less obvious differences between the strains on the shoot compared with the effect on the root. Strong expression of the R. fascians genes, RfIPT, RfLOG and RfCKX, in pea seedlings at 15 days post inoculation was mirrored by increased expression of transporter gene family members in the plant. However, the elevated levels of isopentenyl adenine-type and zeatin-type cytokinins were not consistently associated with the virulent strain. In conclusion, while both the virulent strain and the epiphytic strain impacted the expression of transporter genes in the shoots and roots, only the virulent strain affected morphology. The inhibited root growth, the greening of the roots, and the expressi on of the pea response regulators in the infected roots are indicative of a response to cytokinin, but a role for the ‘classical’ cytokinins as virulence determinants was not established.
Permanent Link: http://hdl.handle.net/11104/0283973