The Seed Composition of Arabidopsis Mutants for the Group 3 Sulfate Transporters Indicates a Role in Sulfate Translocation within Developing Seeds      

Abstract

Sulfate is required for the synthesis of sulfur-containing amino acids and numerous other compounds essential for the plant life cycle. The delivery of sulfate to seeds and its translocation between seed tissues is likely to require specific transporters. In Arabidopsis (Arabidopsis thaliana), the group 3 plasmalemma-predicted sulfate transporters (SULTR3) comprise five genes, all expressed in developing seeds, especially in the tissues surrounding the embryo. Here, we show that sulfur supply to seeds is unaffected by T-DNA insertions in the SULTR3 genes. However, remarkably, an increased accumulation of sulfate was found in mature seeds of four mutants out of five. In these mutant seeds, the ratio of sulfur in sulfate form versus total sulfur was significantly increased, accompanied by a reduction in free cysteine content, which varied depending on the gene inactivated. These results demonstrate a reduced capacity of the mutant seeds to metabolize sulfate and suggest that these transporters may be involved in sulfate translocation between seed compartments. This was further supported by sulfate measurements of the envelopes separated from the embryo of the sultr3;2 mutant seeds, which showed differences in sulfate partitioning compared with the wild type. A dissection of the seed proteome of the sultr3 mutants revealed protein changes characteristic of a sulfur-stress response, supporting a role for these transporters in providing sulfate to the embryo. The mutants were affected in 12S globulin accumulation, demonstrating the importance of intraseed sulfate transport for the synthesis and maturation of embryo proteins. Metabolic adjustments were also revealed, some of which could release sulfur from glucosinolates.

CURLY LEAF Regulates Gene Sets Coordinating Seed Size and Lipid Biosynthesis

“…S9). By analysis of public microarray datasets derived from tissue/cell types samples of embryos (Le et al, 2010;Zuber et al, 2010;Belmonte et al, 2013), we found these five organ-size genes were preferentially expressed at the mature-green, bentcotyledon, and/or the linear-cotyledon stages (Supplemental Fig. S11).…”

“…Blue line shows average relative expression levels. F, Relative expression levels of CRGs in 42 embryonic compartments at six stages of seed development (Zuber et al, 2010). Samples were as described in Supplemental Data Set 1.…”

“…To extend our analysis to the tissue-/cell-type level, we compared our results with 87 published microarray datasets profiling 42 tissues and/or cell types isolated by laser capture microdissection at six different stages of embryo development (Le et al, 2010;Zuber et al, 2010;Belmonte et al, 2013) and reanalyzed the datasets according to the Arabidopsis TAIR10 annotation. CRGs were preferentially expressed at the late stages of embryo development, especially in several tissue/ cell types at the mature-green stage, such as embryo proper, peripheral endosperm, chalazal endosperm, chalazal seed coat, and seed coat, followed by the bending-cotyledon and the linear-cotyledon stages ( Fig.…”

Identification of new QTLs for seed mineral, cysteine, and methionine concentrations in soybean [Glycine max (L.) Merr.]

“…An S transporter gene, SULTR3;3, was detected in the QTL interval for N:S ratio on chromosome 20. Group 3 sulfate transporters are predicted to be located on the plasma membrane (Kataoka et al 2004;Zuber et al 2010), and could be involved in sulfate translocation between seed compartments (Zuber et al 2010). Selenate uptake in plants is mediated by sulfate transporters because of chemical similarities between S and Se (Anderson 1993).…”

A Guideline to Family-Wide Comparative State-of-the-Art Quantitative RT-PCR Analysis Exemplified with a Brassicaceae Cross-Species Seed Germination Case Study

“…A list of all analyzed microarray experiments can be found in Supplemental Data Set 2 online. The complete microarray data set (Seed Total, 101 experiments) was partitioned in different subseries: Germination Total (67 experiments focusing on seed germination, based on different sources), Development Total (34 experiments focusing on seed development, based on the Goldberg-Harada data set; http://seedgenenetwork.net/; Le et al, 2010;Zuber et al, 2010) (also available via GEO, http://www.ncbi.nlm.nih.gov/ geo, accession number GSE12404), and Development Endosperm (24 experiments, a subseries of the Development Total data set focusing only on endosperm-derived data). Based on embryo development, the Arabidopsis endosperm data set contains preglobular, globular, heart, linear cotyledon, and mature green stages.…”