Impact of cadmium and zinc on proteins and cell wall-related gene expression in young stems of hemp (Cannabis sativa L.) and influence of exogenous silicon

Abstract The study aims to determine the impact of Cd (20 μM) and Zn (100 μM) in the presence or absence of Si (2 mM) on plant development and fibre differentiation in young stem of hemp (Cannabis sativa L.). Gene expression and proteome involved in fibre development were analyzed. Both elements reduced the diameter of primary bast fibres. Cadmium negatively affected cellulose and lignin biosynthesis and decreased substitution of xylan in fibres, while Zn had an opposite impact on cellulose metabolism. Only a minor proportion of proteins were affected by both Cd and Zn, suggesting that the two heavy metals have a quite different impact on protein regulation in C. sativa. Si had a specific impact on some proteins observed in CdSi treatment comparatively to plants exposed to Cd in the absence of Si: 55 % of those proteins (10 among 18) were specifically regulated by this treatment and remained unaffected by Cd or Si applied alone. Six proteins were significantly regulated in ZnSi-exposed plants comparatively to Zn-treated ones and none of them was specifically regulated by Si in the absence of Zn. Diameter of bast fibre increased in response to Si in Cd-treated plants. This confirms that the presence of protecting Si confers a specific physiological status in relation to cell wall differentiation to heavy metal-treated plants.