Comparative transcriptome and proteome analysis to reveal the biosynthesis of gold nanoparticles in Arabidopsis.

A large number of plants have been tested and exploited in search of a green chemistry approach for the fabrication of gold or other precious metal nanomaterials. Despite the potential of plant based methods, very little is known about the underlying biochemical reactions and genes involved in the biotransformation mechanism of AuCl4 into gold nanoparticles (AuNPs). In this research, we thus focused on studying the effect of Au on growth and nanoparticles formation by analyses of transcriptome, proteome and ionome shift in Arabidopsis. Au exposure favored the growth of Arabidopsis seedling and induced formation of nanoparticles in root and shoot, as indicated by optical and hyperspectral imaging. Root transcriptome analysis demonstrated the differential expression of the members of WRKY, MYB and BHLH gene families, which are involved in the Fe and other essential metals homeostasis. The proteome analysis revealed that Glutathione S-transferases were induced in the shoot and suggested its potential role in the biosynthesis AuNPs. This study also demonstrated the role of plant hormone auxin in determining the Au induced root system architecture. This is the first study using an integrated approach to understand the in planta biotransformation of KAuCl4 into AuNPs.