Investigation of selenium tolerance mechanisms in Arabidopsis thaliana

Abstract

To investigate selenium tolerance mechanisms in Arabidopsis thaliana, genetic and physiologic studies were performed in the three Arabidopsis accessions Landsberg erecta (Ler), Columbia (Col) and Wassilewskija (Ws). Accession Ler was significantly less tolerant to selenate than Ws and Col, whereas Ws was less tolerant to selenite than the others. Analysis of selenium tolerance in F 1 and F 2 plants obtained from crosses between these accessions suggest that multiple genes are involved in selenate tolerance and a single major gene controls selenite tolerance in these populations. Bulked segregant analysis in two F 2 populations indicated that molecular marker ciw7 on chromosome 4 is linked to selenite tolerance, and three molecular markers on chromosomes 1, 3 and 5 (nga111, ciw4 and ciw8, respectively) are linked to selenate tolerance. The ecotypic variation in selenite tolerance appeared to be correlated with root levels of non-protein thiols. Also, the shoot tissue levels of selenocysteine (SeCys) and selenocystine were correlated with tolerance to both selenate and selenite. Judging from RT-PCR results, several sulfate transporters and S assimilatory enzymes appear to be upregulated by selenate and selenite at the transcriptional level. A potential SeCys methyltransferase was expressed at lower levels in selenite-sensitive Ws than in the other two, when grown on selenite. Together, these studies show that there is substantial intraspecific variation in tolerance to selenate and selenite in Arabidopsis, and provide insights into the genetic and biochemical mechanisms underlying the observed ecotypic differences.

Cooperative Ethylene and Jasmonic Acid Signaling Regulates Selenite Resistance in Arabidopsis

“…Thus, Ws-2 is more susceptible to selenite than Col-0. These results confirm the report by Zhang et al (2006a) that an Arabidopsis Col accession was more resistant to selenite than Ws. The difference in tolerance index was most pronounced (2-fold) when plants were grown on medium containing 15 or 20 mM selenite, and 15 mM was chosen for all subsequent experiments.…”

“…The cellular mechanisms regulating ROS production in response to Se in plants are not clear at this point and will require further study. In this context, it is interesting to note that Zhang et al (2006a) showed that a molecular marker on chromosome 4 (ciw7) appeared to be linked to selenite resistance in Col. Although no ethylene-or JA-related gene is found around the marker, a potential defense-related gene, LSD1-like 2 (LOL2; At4g21610), is located close to the marker.…”

“…In a previous study, Zhang et al (2006a) showed Ws was sensitive to selenite while Col was resistant. Here, the molecular mechanisms behind this physiological difference were further investigated.…”

Characterization of a Selenate-Resistant Arabidopsis Mutant. Root Growth as a Potential Target for Selenate Toxicity

“…2A). It is possible that other classes of selenate-resistant mutants could still be found, as indicated by the quantitative trait loci (QTL) study that identified QTLs for selenate resistance that were independent of any sulfate transporter (Zhang et al, 2006a(Zhang et al, , 2006b). The fact that in these last studies no identified QTL actually included sultr1;2 does not in any way cast doubt on our results; it merely confirms the fact that different selection criteria (or different definitions of selenate resistance) may lead to the identification of different classes of mutants and genes.…”

Effects of selenium hyperaccumulation on plant–plant interactions: evidence for elemental allelopathy?

“…The element selenium (Se) is an essential micronutrient for many organisms, including mammals. In these organisms Se is incorporated into essential selenoproteins, some of which have antioxidant functions and may help prevent a variety of cancers (Burke, 2002; Zhang et al. , 2006c).…”