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The NRT 2.5 and NRT 2.6 genes are involved in growth promotion of Arabidopsis by the plant growth‐promoting rhizobacterium ( PGPR ) strain Phyllobacterium brassicacearum STM 196
Author(s) -
Kechid Maya,
Desbrosses Guilhem,
Rokhsi Wafaa,
Varoquaux Fabrice,
Djekoun Abdelhamid,
Touraine Bruno
Publication year - 2013
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.12158
Subject(s) - arabidopsis , nitrate reductase , nitrate , arabidopsis thaliana , mutant , biology , botany , microbiology and biotechnology , gene , chemistry , biochemistry , ecology
Summary The Phyllobacterium brassicacearum STM 196 strain stimulates Arabidopsis thaliana growth and antagonizes high nitrate inhibition of lateral root development. A previous study identified two STM 196‐responsive genes, NRT 2.5 and NRT 2.6 (Mantelin et al ., 2006, Planta 223: 591–603). We investigated the role of NRT 2.5 and NRT 2.6 in the plant response to STM 196 using single and double Arabidopsis mutants. The single mutants were also crossed with an nrt2.1 mutant, lacking the major nitrate root transporter, to distinguish the effects of NRT 2.5 and NRT 2.6 from potential indirect effects of nitrate pools. The nrt2.5 and nrt2.6 mutations abolished the plant growth and root system architecture responses to STM 196. The determination of nitrate content revealed that NRT 2.5 and NRT 2.6 do not play an important role in nitrate distribution between plant organs. Conversely, NRT 2.5 and NRT 2.6 appeared to play a role in the plant response independent of nitrate uptake. Using a nitrate reductase mutant, it was confirmed that the NRT 2.5/ NRT 2.6‐dependent plant signalling pathway is independent of nitrate‐dependent regulation of root development. Our findings demonstrate that NRT 2.5 and NRT 2.6, which are preferentially expressed in leaves, play an essential role in plant growth promotion by the rhizospheric bacterium STM 196.