## 3 Results
### Effects of BF06 VOCs on Se Accumulation in Plants  
Previous studies have indicated that Se can be transported into root cells via some sulfate transporter genes [62]. Activating sulfate transporter is conducive to promoting Se uptake and translocation from roots to shoots in plants [51; 52; 53; 54]. In this study, the data of RNA-Seq revealed that the release of VOCs released by BF06 induced the expression of sulfate transporter genes including _SULRT1;1, SULRT1;2, SULTR2;1, SULTR3;5_, indicating that BF06 VOCs was likely involved in the regulation of Se uptake in _Arabidopsis_. Furthermore, analyses of qRT-PCR revealed that the transcription levels of these sulfate transporter genes were markedly upregulated in _Arabidopsis_ after exposure to BF06 VOCs (Figure 11A).  
To further determine the endogenous content of Se in wild-type (WT) plants, seven-day-old seedlings were firstly grown on a 1/2 MS medium, then transferred to a 1/2 MS medium containing 10 or 30 \(\upmu\)M Se and grown for 10 days with or without exposure to BF06 VOCs. Our data showed that the content of Se in the VOCs-exposed WT shoots was increased by about 23% compared with that in non VOCs-exposed (control) plants, and the roots of VOCs-exposed plants displayed higher Se accumulation than the controls (Figure 11B). However, the content of Se was significantly higher in  
Figure 9: Phenotype of the BF06 VOCs-exposed _Arabidopsis_ plants after treatment with L-NAME or c-PTIO. _Arabidopsis_ plants were grown on an alkaline MS medium (pH = 7.6) for seven days, then transferred to 1/2 MS medium containing different Fe levels (0, 5, 20, or 50 \(\upmu\)M Fe(III)-EDTA) with exposure to BF06 VOCs for 10 days. However, treatment with L-NAME or c-PTIO diminished the positive effects of BF06 VOCs on alleviating plant Fe deficiency.  
shoots of VOCs-exposed WT plants than the VOCs-exposed WT roots. Moreover, the effects of BF06 VOCs on the Se accumulation in _sultr1;2_ mutants were analyzed. As shown in Figure 11B, the shoots of _sultr1;2_ mutants accumulated less Se than WT plants after two weeks of exposure to BF06 VOCs. Similar results were observed for the roots. These results indicated that the VOCs-induced expression of sulfate transporter genes was responsible for improving Se accumulation in plants.  
Figure 11: Effects of BF06 VOCs on the expression of some sulfate transporter genes, and Se accumulation in _Arabidopsis_ plants. Seven-day-old seedlings were treated with or without exposure to BF06 VOCs for 10 days, then these plants were sampled to analyze the expression of sulfate transporter genes including _SULRT1;1, SULRT1;2, SULRT2;1, SULRT2;2_, and SULRT3;5_ (**A**); Furthermore, the content of Se was examined in shoots and roots of both the WT and _sultr1;2_ mutants after 10 days of exposure to BF06 VOCs, respectively (**B**). Different letters represent the significant difference of the comparisons at \(p\) < 0.05.  
Figure 10: Treatment with L-NAME or c-PTIO reduced the content of chlorophyll and Fe in _Arabidopsis_ plants after exposure to BF06 VOCs. _Arabidopsis_ plants were grown on an alkaline MS medium (pH = 7.6) for seven days, then transferred to a 1/2 MS medium containing different Fe concentrations (0, 5, 20, or 50 uM Fe(III)-EDTA) with exposure to BF06 VOCs for 10 days. Subsequently, these plants were sampled to measure the content of chlorophyll (**A**), total Fe (**B**), shoot (**C**) and root (**D**) soluble Fe, and root cell wall Fe (**E**). Different letters represent a significant difference between the control and VOCs-exposed plants at \(p\) < 0.05.