Abstract
Silicon (Si) is the second most abundant element in soil and has several beneficial effects, especially in plants subjected to stress conditions. However, the effect of Si in preventing nitrogen (N) starvation in plants is poorly documented. The aim of this work was to study the effect of a short Si supply duration (7 days) on growth, N uptake, photosynthetic activity, and leaf senescence progression in rapeseed subjected (or not) to N starvation. Our results showed that after 1 week of Si supply, Si improves biomass and increases N uptake and root expression of a nitrate transporter gene. After 12 days of N starvation, compared to -Si plants, mature leaf from +Si plants showed a high chlorophyll content, a maintain of net photosynthetic activity, a decrease of oxidative stress markers [hydrogen peroxide (H2O2) and malondialdehyde (MDA)] and a significant delay in senescence. When N-deprived plants were resupplied with N, a greening again associated with an increase of photosynthetic activity was observed in mature leaves of plants pretreated with Si. Moreover, during the duration of N resupply, an increase of N uptake and nitrate transporter gene expression were observed in plants pretreated with Si. In conclusion, this study has shown a beneficial role of Si to alleviate damage associated with N starvation and more especially its role in delaying of leaf senescence.
Highlights
In the lithosphere, silicon (Si) is the second most abundant element after oxygen both in terms of weight and number of atoms (Epstein, 1994)
Except a decrease of root trans-zeatin (t-Z) content observed in plant treated with Si, all other cytokinin contents at Day 0 (D0) (and especially N6Isopentenyladenine (IP) considered as one of the main active forms) studied in roots and shoots remained the same level in −Si and +Si plants (Figure 3 and Supplementary Table S1)
Our study showed that Brassica napus, which is considered a non-Si accumulator species (
Summary
Silicon (Si) is the second most abundant element after oxygen both in terms of weight and number of atoms (Epstein, 1994). Despite this high abundance in soil, Si is never found in a free form but usually combined with other elements to form oxides compounds or silicates, which are not available for plant nutrition. Only a low proportion of Si is taken up by roots in the form of uncharged silicic acid [Si(OH)4], which is present in the soil solution at concentrations ranging from 0.1 to 0.6 mM (Epstein, 1994). Si is polymerized and accumulated in amorphous forms in plant tissues (SiO2-nH20)
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