Assessing the Effect of Silicon Supply on Root Sulfur Uptake in S-Fed and S-Deprived Brassica napus L.

Abstract

Silicon (Si) is known to alleviate many nutritional stresses. However, in Brassica napus, which is a highly S-demanding species, the Si effect on S deficiency remains undocumented. The aim of this study was to assess whether Si alleviates the negative effects of S deficiency on Brassica napus and modulates root sulfate uptake capacity and S accumulation. For this, Brassica napus plants were cultivated with or without S and supplied or not supplied with Si. The effects of Si on S content, growth, expression of sulfate transporter genes (BnaSultr1.1; BnaSultr1.2) and sulfate transporters activity in roots were monitored. Si supply did not mitigate growth or S status alterations due to S deprivation but moderated the expression of BnaSultr1.1 in S-deprived plants without affecting the activity of root sulfate transporters. The effects of Si on the amount of S taken-up and on S transporter gene expression were also evaluated after 72 h of S resupply. In S-deprived plants, S re-feeding led to a strong decrease in the expression of both S transporter genes as expected, except in Si-treated plants where BnaSultr1.1 expression was maintained over time. This result is discussed in relation to the similar amount of S accumulated regardless of the Si treatment.

Silicon Supply Improves Nodulation and Dinitrogen Fixation and Promotes Growth in Trifolium incarnatum Subjected to a Long-Term Sulfur Deprivation

“…This study demonstrated that the growth of Trifolium incarnatum was not affected by S deficiency during the 21 first days of treatment ( Figure 1 ). This result agrees with previous work performed in Brassica napus cultivated in hydroponic conditions and subjected to the same duration of S-deprivation [ 28 ]. In contrast, when the S-deprivation was prolonged (D63), this study showed that a strong decrease in both shoot and total biomasses occurred in -S-Si plants compared to +S-Si plants ( Figure 1 ).…”

“…Silicon is largely known to alleviate negative effects of abiotic stress in plants [ 26 , 28 , 35 , 36 ] and to improve plant health [ 30 ]. However, the effect of Si supply on S-deprived plants is currently poorly documented, as reported by [ 27 , 37 ].…”

“…In the same way, a Si supply enables better tolerance to salt stress by sustaining various biological process such as photosynthesis or by stimulating detoxification of reactive oxygen species (ROS) [ 25 ]. Moreover, it has been shown that Si supplementation is beneficial in plants subjected to nutrient deficiency, such as deficits in N, P and K, and to a lesser extent S [ 26 , 27 , 28 ]. In legumes, the beneficial effects of silicon have also been demonstrated in plants subject to a large panel of abiotic stresses.…”

“…Although Si has several beneficial effects under a variety of adverse conditions, there are currently no studies that have focused on the effects of Si application to legumes subjected to S-deficiency. Indeed, currently only three studies demonstrate beneficial effects of Si application in barley [ 31 ], rice [ 32 ] and rapeseed [ 28 ] subjected to S-deficiency. In this study, we focused on Trifolium incarnatum because previous studies have shown that this legume species is of agroecological interest especially when it cultivated in mixed crops.…”

Silicon Enhances Brassica napus Tolerance to Boron Deficiency by the Remobilisation of Boron and by Changing the Expression of Boron Transporters

“…For example, in rapeseed, Si has been shown to alleviate the effect of nitrogen deficiency by delaying leaf senescence and promoting the expression of N transporters [38]. Nevertheless, in a recent study, no clear positive influence of Si could be observed in rapeseed plants under S deficiency: Si supply did not increase the biomass or S content in these conditions [39]. Regarding B and Si interaction, most of the work has been focused on the effect of Si in alleviating B toxicity [40][41][42][43][44][45].…”