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Nitric oxide is required for an optimal establishment of the Medicago truncatula–Sinorhizobium meliloti symbiosis
Author(s) -
del Giudice Jennifer,
Cam Yvan,
Damiani Isabelle,
FungChat Franck,
Meilhoc Eliane,
Bruand Claude,
Brouquisse Renaud,
Puppo Alain,
Boscari Alexandre
Publication year - 2011
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/j.1469-8137.2011.03693.x
Subject(s) - medicago truncatula , sinorhizobium meliloti , biology , nitric oxide , rhizobia , symbiosis , mutant , root nodule , rhizobium , microbiology and biotechnology , rhizobiaceae , botany , medicago , gene , biochemistry , bacteria , genetics , endocrinology
Summary• Nitric oxide (NO) is a gaseous molecule that participates in numerous plant signalling pathways. It is involved in plant responses to pathogens and development processes such as seed germination, flowering and stomatal closure. • Using a permeable NO‐specific fluorescent probe and a bacterial reporter strain expressing the lacZ gene under the control of a NO‐responsive promoter, we detected NO production in the first steps, during infection threads growth, of the Medicago truncatula – Sinorhizobium meliloti symbiotic interaction. Nitric oxide was also detected, by confocal microscopy, in nodule primordia. • Depletion of NO caused by cPTIO (2‐(4‐carboxyphenyl)‐4,4,5,5‐tetramethyl imidazoline‐1‐oxyl‐3‐oxide), an NO scavenger, resulted in a significant delay in nodule appearance. The overexpression of a bacterial hmp gene, encoding a flavohaemoglobin able to scavenge NO, under the control of a nodule‐specific promoter (pENOD20) in transgenic roots, led to the same phenotype. The NO scavenging resulting from these approaches provoked the downregulation of plant genes involved in nodule development, such as MtCRE1 and MtCCS52A . Furthermore, an Hmp‐overexpressing S. meliloti mutant strain was found to be less competitive than the wild type in the nodulation process. • Taken together, these results indicate that NO is required for an optimal establishment of the M. truncatula–S. meliloti symbiotic interaction.