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Unraveling the effect of arsenic on the model M edicago– E nsifer interaction: a transcriptomic meta‐analysis
Author(s) -
Lafuente Alejandro,
PérezPalacios Patricia,
Doukkali Bouchra,
MolinaSánchez María D.,
JiménezZurdo José I.,
Caviedes Miguel A.,
RodríguezLlorente Ignacio D.,
Pajuelo Eloísa
Publication year - 2015
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.13009
Subject(s) - rhizobia , biology , symbiosis , root nodule , nitrogen fixation , microbiology and biotechnology , gene , botany , biochemistry , genetics , bacteria
Summary The genetic regulation underlying the effect of arsenic (As( III )) on the model symbiosis M edicago– E nsifer was investigated using a combination of physiological (split‐roots), microscopy and genetic (microarrays, q RT ‐ PCR and composite plants) tools. Nodulation was very sensitive to A s( III ) (median inhibitory dose ( ID 50) = 20 μM). The effect on root elongation and on nodulation was local (nonsystemic). A battery of stress (salt, drought, heat shock, metals, etc.)‐related genes were induced. Glutathione played a pivotal role in tolerance/detoxification, together with secondary metabolites ((iso)flavonoids and phenylpropanoids). However, antioxidant enzymes were not activated. Concerning the symbiotic interaction, molecular evidence suggesting that rhizobia alleviate A s stress is for the first time provided. Chalcone synthase (which is involved in the first step of the legume–rhizobia cross‐talk) was strongly enhanced, suggesting that the plants are biased to establish symbiotic interactions under As( III ) stress. In contrast, 13 subsequent nodulation genes (involved in nodulation factors (Nod factors) perception, infection, thread initiation and progression, and nodule morphogenesis) were repressed. Overexpression of the ethylene responsive factor ERN in composite plants reduced root stress and partially restored nodulation, whereas overexpression of the early nodulin ENOD 12 enhanced nodulation both in the presence and, particularly, in the absence of A s, without affecting root elongation. Several transcription factors were identified, which could be additional targets for genetic engineering aiming to improve nodulation and/or alleviate root stress induced by this toxic.