Soybean Seed Coat Peroxidase (A Comparison of High-Activity and Low-Activity Genotypes)

Abstract

; and Agriculture Canada, Research Station, Harrow, Ontario, Canada NOR 1 GO (R.I.B.)Peroxidase activity in the seed coats of soybean (Clycine max [LI Merr.) is controlled by the Ep locus. We compared peroxidase activity in cell-free extracts from seed coat, root, and leaf tissues of three EpEp cultivars (Harosoy 63, Harovinton, and Coles) to three epep cultivars (Steele, Marathon, and Raiden). Extracts from the seed coats of EpEp cultivars were 100-fold higher in specific activity than those from epep cultivars, but there was no difference in specific activity in crude root or leaf extracts. lsoelectric focusing of root tissue extracts and staining for peroxidase activity showed that EpEp cultivars had a root peroxidase of identical isoelectric point to the seed coat peroxidase, whereas roots of the epep types were lacking that peroxidase, indicating that the Ep locus may also affect expression in the root. In seed coat extracts, peroxidase was the most abundant soluble protein in €p€p cultivars, whereas this enzyme was present only in trace amounts in epep genotypes, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Histochemical localization of peroxidase activity in seed coats of EpEp cultivars shows that the enzyme occurs predominately in the cytoplasm of hourglass cells of the subepidermis. No obvious difference in the gross or microscopic structure of the seed coat was observed to be associated with the Ep locus. These results suggest that soybean seed coat peroxidase may be involved in processes other than seed coat biosynthesis.

SCB1 , a BURP-domain protein gene, from developing soybean seed coats

“…Maple Presto) seed coat cDNA library, prepared from seeds ranging in size from <50 mg to 250 mg fresh weight, was differentially screened for seed coat-specific genes. A number of genes were isolated including the peroxidase genes, Ep and Prx2 (Gijzen et al 1993(Gijzen et al , 1999aGijzen 1997), a seed coat subtilase gene, SCS1 (Batchelor et al 2000), and a cell wall proline-rich protein gene (unpublished). A variety of unidentified genes were also isolated, including SCB1, which showed preferential expression in the seed coat.…”

Hydrophobic Protein Synthesized in the Pod Endocarp Adheres to the Seed Surface1

“…This trait is in part determined by the I locus, a cluster of chalcone synthase genes that control anthocyanin biosynthesis in the seed coat (Todd and Vodkin, 1996). There is also variation in the composition of proteins from seed coats of different soybean varieties (Lindstrom and Vodkin, 1991;Gijzen et al, 1993), and corresponding genes encoding both structural and soluble seed coat proteins have been isolated (Schmidt et al, 1994;Gijzen, 1997). Despite these examples, there are no clear genetic or biochemical models to account for many of the observed phenotypes.…”

A deletion mutation at the ep locus causes low seed coat peroxidase activity in soybean

“…The seven potential glycosylation sites identified from the amino acid sequence would accommodate the five or six N-linked glycosylation sites proposed by Gray et al (1996). The molecular mass of the enzyme has been determined by denaturing gel electrophoresis to be 37 kDa (Gillikin and Graham, 1991;Sessa and Anderson, 1981)or 43 kDa (Gijzen et aL, 1993). Analysis by mass spectrometry indicated a mass of 40 622 Da for the apo-enzyme and 33 250 Da after deglycosylation (Gray etal., 1996).…”