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Seed calcium content is an important quality attribute of specialty soybean [Glycine max (L.) Merr.] for soyfoods. However, analyzing seed for calcium content is time consuming and labor intensive. Knowing quantitative trait loci (QTL) for seed calcium will facilitate the development of elite cultivars with proper calcium content through marker-assisted selection (MAS). The objective of his study was to identify major QTL associated with calcium content in soybean seed. Calcium content was tested in 17 F2.3 and 157 F2.4 lines derived from the cross of SS-516 (low calcium) x Camp (high calcium). The F2.3 lines were genotyped with 148 simple sequence repeat markers in a previous study on seed hardness, and the genotypic data were used in the QTL analysis of the current study. Four QTL designated as Ca1, Ca2, Ca3, and Ca4 orp linkage groups (LGs) A2, 1, and M were identified by both single- marker analysis and composite-interval mapping, and the QTL accounted for 10.7%, I 6.3%, 14.9%, and 9.7% of calcium content variation, respectively. In addition, multiple- interval mapping analysis revealed a significant dominant-by- dominant interaction effect between Cal and Ca3, which accounted for 4.3% calcium content variation. These QTL will facilitate the implementation of MAS for calcium content in soybean-breeding programs. [ABSTRACT FROM AUTHOR]

J05 soybean was previously identified to carry 2 independent genes, Rsv1 and Rsv3, for "soybean mosaic virus" (SMV) resistance by inheritance and allelism studies. The objective of this research was to confirm the 2 genes in J05 using molecular markers so that a marker-assisted selection can be implemented. The segregation of F2 plants from J05 x Essex exhibited a good fit to a 3:1 ratio when inoculated with SMV Gi. Three simple sequence repeat (SSR) markers near Rsv1, Satt114, Satt510, and Saṯ 154, amplified polymorphic DNA fragments between J05 and Essex and were closely linked to the gene on soybean molecular linkage group (MLG) F, thus verifying the presence of Rsv1 in J05 for resistance to SMV G1. The presence of Rsv1 in J05 was confirmed by 2 closely linked SSR markers on MLG B2, Satt726 and Saṯ424, in F2:3 lines that were derived from the SMV GI-susceptible F2 plants and segregated in a 1:2:1 ratio for reaction to SMV G7. Two closely linked markers for Rsv4, Satt296 and Satt542, segregated independently of SMV resistance, indicating the absence of Rsv4 inJO5. These SSR markers for Rsvl and Rsv3 can serve as a useful molecular tool for selection and pyramiding of genes in J05 for SMV resistance. [ABSTRACT FROM AUTHOR]

Synthesis and accumulation of seed storage proteins (SSPs) is an important aspect of the seed maturation program. Genes encoding SSPs are specifically and highly expressed in the seed during maturation. However, the mechanisms that repress the expression of these genes in leaf tissue are not well understood. To gain insight into the repression mechanisms, we performed a genetic screen for mutants that express SSPs in leaves. Here, we show that mutations affecting BRAHMA (BRM), a SNF2 chromatin-remodeling ATPase, cause ectopic expression of a subset of SSPs and other embryogenesis-related genes in leaf tissue. Consistent with the notion that such SNF2-like ATPases form protein complexes in vivo, we observed similar phenotypes for mutations of AtSWI3C, a BRM-interacting partner, and BSH, a SNF5 homolog and essential SWI/SNF subunit. Chromatin immunoprecipitation experiments show that BRM is recruited to the promoters of a number of embryogenesis genes in wild-type leaves, including the 2S genes, expressed in brm leaves. Consistent with its role in nucleosome remodeling, BRM appears to affect the chromatin structure of the At2S2 promoter. Thus, the BRM-containing chromatin-remodeling ATPase complex involved in many aspects of plant development mediates the repression of SSPs in leaf tissue. [ABSTRACT FROM AUTHOR]