Root Silicon Treatment Modulates the Shoot Transcriptome in Brassica napus L. and in Particular Upregulates Genes Related to Ribosomes and Photosynthesis

Abstract

While the benefit of silicon (Si) is often reported in cultivated plants, and particularly in those experiencing stress conditions, the underlying mechanisms are poorly described and controversial [1]. For a long time the mechanical role of Si in the cell wall has been considered as the main explanation for its beneficial effects in alleviating plant stresses. Another assumption is that a low proportion (around 1%) of the Si taken up by plants might modulate some metabolic pathways. Investigating this concept, Haddad et al. [2] demonstrated that in roots of Brassica napus plants, the modulation of a large range of genes by Si could explain an increased resistance to nitrogen (N) deficiency. However, since the Si benefit is mainly associated with maintaining photosynthetic activity and a delay in leaf senescence in the mature leaves of plants cultivated under N- deficiency [3], the aim of the present study was to identify (using a RNA sequencing approach) the transcriptomic modifications in the shoot compartment of +Si plants. Our results showed that there were 296 genes differentially expressed genes (DEGs)) in shoots of Brassica napus treated with Si (root supply 1.7 mM for 7 days). Among these genes, 19 and 31 upregulated genes were related to ribosomes and photosynthetic pathways, respectively. From these results, the assumption that a Si supply can facilitate efficient metabolic reinforcement and alleviate the biotic and abiotic stresses experienced by plants is discussed.