RESUMEN
Increasing the production of plant oils such as soybean oil as a renewable resource for food and fuel is valuable. Successful breeding for higher oil levels in soybean, however, usually results in reduced protein, a second valuable seed component. This study shows that by manipulating a highly active acyl-CoA:diacylglycerol acyltransferase (DGAT) the hydrocarbon flux to oil in oilseeds can be increased without reducing the protein component. Compared to other plant DGATs, a DGAT from Vernonia galamensis (VgDGAT1A) produces much higher oil synthesis and accumulation activity in yeast, insect cells, and soybean. Soybean lines expressing VgDGAT1A show a 4% increase in oil content without reductions in seed protein contents or yield per unit land area. Incorporation of this trait into 50% of soybeans worldwide could result in an increase of 850 million kg oil/year without new land use or inputs and be worth â¼U.S.$1 billion/year at 2012 production and market prices.
Asunto(s)
Diacilglicerol O-Acetiltransferasa/metabolismo , Aceites de Plantas/análisis , Proteínas de Plantas/genética , Vernonia/enzimología , Clonación Molecular , Diacilglicerol O-Acetiltransferasa/genética , Ácidos Grasos/análisis , Regulación de la Expresión Génica de las Plantas , Genes de Plantas , Proteínas de Plantas/análisis , Plantas Modificadas Genéticamente/química , Plantas Modificadas Genéticamente/genética , Semillas/química , Semillas/genética , Glycine max/química , Glycine max/genética , Vernonia/genéticaRESUMEN
Infection of soybean [Glycine max (L.) Merr.] plants with Soybean mosaic virus (SMV) has been reported to enhance Phomopsis spp. infection, which reduces seed quality. The timing and incidence of SMV infection depends largely upon the level of primary inoculum and aphid-activity. Two field experiments were conducted in aphid-free environments, to examine the influence of (i) SMV-infection, and (ii) SMV-resistance alleles of the Rsv(1) gene, on the incidence of Phomopsis spp. seed infection. In the first experiment, mock inoculated (potassium phosphate buffer) SMV-susceptible cultivars (Clark and Williams), and their SMV-resistant isolines (L78-434 and L78-379, with dominant Rsv(1) allele conferring resistance to SMV strains G1-G6), showed low levels (<10%) of Phomopsis spp. seed infection. In contrast, susceptible cultivars mechanically inoculated with SMV (G2 strain, V8 stage) exhibited a 3- to 8-fold increase in the incidence Phomopsis spp. seed infection. In the second experiment, mock inoculation of the susceptible cultivar, Clark, and two SMV-resistant lines (10-rsv(1)(y) and 18-rsv(1)(y), with recessive rsv(1)(y) allele conferring resistance to SMV strains G1-G3), resulted in <20% Phomopsis spp. seed infection. In contrast, those plants mechanically inoculated with SMV (strain G6, V8 stage) had significantly higher levels of Phomopsis spp. seed infection (52 to 78%). It is concluded that the lower incidence of Phomopsis spp. seed infection in SMV-resistant plants was not due to the SMV resistance alleles of the Rsv(1) gene per se, but rather due to the absence of SMV infection. Thus, the use of SMV-resistant varieties prevented/reduced SMV and Phomopsis spp. seed infection.
RESUMEN
ABSTRACT Isolates of Bean pod mottle virus (BPMV), a member of the genus Comovirus, collected from soybean fields in Kentucky, Virginia, Arkansas, and Iowa were classified into two distinct subgroups, I and II, based on nucleic acid hybridization analysis using cloned cDNA probes to RNA-1 from BPMV strains K-G7 and K-Ha1. Slot blot hybridization analysis using cloned cDNA probes to RNA-2 from the same two strains (K-G7 and K-Ha1), however, revealed that some of the isolates, initially classified as belonging to subgroup I after analysis with RNA-1 probes, are in fact natural reassortants between the two strain subgroups. This was corroborated by nucleotide sequence analysis of full-length cDNA clones of both RNA-1 and RNA-2 from a putative reassortant strain (K-Ho1). These results indicate that BPMV strain diversity is more complex than initially anticipated, and that the use of cloned probes to both genomic RNAs during nucleic acid hybridization analysis is required to unravel the extent of such diversity. In a field plot experiment, BPMV isolates that belong to distinct strain subgroups induced symptoms that varied in severity and in the level of yield losses. In this regard, the reassortant strain K-Ho1 caused the most serious damage compared with four other BPMV isolates tested. Furthermore, the soybean alleles Rsv(1) and Rsv(4), known to confer resistance against Soybean mosaic virus, a member of the genus Potyvirus, did not provide any protection against BPMV. Additionally, we developed a reverse transcription-polymerase chain reaction procedure based on the sequence of a highly conserved region in the capsid polyprotein coding sequence that provides efficient and highly sensitive detection of all BPMV isolates tested, regardless of their strain classification.
