(Homo)glutathione depletion modulates host gene expression during the symbiotic interaction between Medicago truncatula and Sinorhizobium meliloti.

摘要

Under nitrogen-limiting conditions, legumes interact with symbiotic rhizobia to produce nitrogen-fixing root nodules.We have\udpreviously shown that glutathione and homoglutathione [(h)GSH] deficiencies impaired Medicago truncatula symbiosis\udefficiency, showing the importance of the low Mr thiols during the nodulation process in the model legume M. truncatula. In\udthis study, the plant transcriptomic response to Sinorhizobium meliloti infection under (h)GSH depletion was investigated using\udcDNA-amplified fragment length polymorphism analysis. Among 6,149 expression tags monitored, 181 genes displayed\udsignificant differential expression between inoculated control and inoculated (h)GSH depleted roots. Quantitative reverse\udtranscription polymerase chain reaction analysis confirmed the changes in mRNA levels. This transcriptomic analysis shows a\uddown-regulation of genes involved in meristem formation and a modulation of the expression of stress-related genes in\ud(h)GSH-depleted plants. Promoter-b-glucuronidase histochemical analysis showed that the putative MtPIP2 aquaporin might\udbe up-regulated during nodule meristem formation and that this up-regulation is inhibited under (h)GSH depletion. (h)GSH\uddepletion enhances the expression of salicylic acid (SA)-regulated genes after S. meliloti infection and the expression of SAregulated\udgenes after exogenous SA treatment. Modification of water transport and SA signaling pathway observed under\ud(h)GSH deficiency contribute to explain how (h)GSH depletion alters the proper development of the symbiotic interaction.