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Soil salinity significantly reduces soybean (Glycine max L.) production worldwide. Plants resistance to stress conditions is a complex characteristic regulated by multiple signaling pathways. The v-Myb avian myeloblastosis viral oncogene homolog (MYB) transcription factor (TF) plays a crucial role in plant development, secondary metabolism, and abiotic stress responses. GmMYB68-overexpression and RNA interference (RNAi) lines were established for examining the function of G. max GmMYB68 in plant responses to abiotic stresses. The predicted amino acid sequence of GmMYB68 was similar to that of R2R3-MYB proteins. Quantitative real-time PCR analysis revealed that GmMYB68 expression varied in response to abiotic stresses. GmMYB68-overexpression lines showed enhanced resistance to salt and alkali stresses and their osmotic adjustment and photosynthetic rates were also stronger than that of GmMYB68-RNAi and wild type plants. Although wild type and transgenic plants showed no significant differences in agronomic traits under normal conditions, the overexpression of GmMYB68 increased grain number and 100-grain weights under salt stress. Our study identified a valuable TF associated with stress response in soybean, as its overexpression might help improve salt and alkali tolerance in soybean and other crops. Key words: Glycine max, GmMYB68, MYB family, salt tolerance. La salinite des sols contribue a diminuer significativement la production du soya (Glycine max L.) a l'echelle mondiale. La resistance aux stress chez les plantes est un caractere complexe regule par de nombreuses voies de signalisation. Le facteur de transcription homologue a l'oncogene du virus de la myeloblastose aviaire (v-Myb) joue des roles importants dans le developpement de la plante, dans le metabolisme secondaire et les reponses aux stress abiotiques. Des lignees sur-exprimant ou sous-exprimant (via l'ARNi) le gene GmMYB68 ont ete produites afin d'etudier la fonction de ce gene chez le G. max en reponse aux stress abiotiques. La sequence peptidique predite de GmMYB68 etait semblable a celles des proteines R2R3-MYB. Des analyses PCR en temps reel ont revele que l'expression du gene GmMYB68 variait en reponse aux stress abiotiques. Les lignees sur-exprimant ce gene ont montre une resistance accrue a la salinite et a l'alcalinite et que leur ajustement osmotique ainsi que leur activite photosynthetique etaient plus eleves que chez les lignees GmMYB68-ARNi ou sauvages. Bien que les plantes de type sauvage et les plantes transgeniques ne presentaient aucune difference au plan agronomique en conditions normales, la surexpression de GmMYB68 a augmente le nombre de grains et le poids de 100 grains en conditions de stress salin. Cette etude a permis d'identifier un facteur de transcription important associe a la reponse aux stress chez le soya, et a montre que sa surexpression pourrait contribuer a ameliorer la tolerance a la salinite et a l'alcalinite chez le soya et d'autres cultures. [Traduit par la Redaction] Mots-cles : Glycine max, GmMYB68, famille MYB, tolerance a la salinite., Introduction Soil salinity is a major detrimental factor for crop productivity (Munns and Gilliham 2015). Previous research has demonstrated that salt and alkaline salt stresses are two distinct types of [...]

Soybean mosaic virus (SMV), a member of Potyvirus, is the most destructive and widespread viral disease in soybean production. Our earlier studies identified a soybean 40S ribosomal protein S8 (GmRPS8) using the 6K1 protein of SMV as the bait to screen a soybean cDNA library. The present study aims to identify the interactions between GmRPS8 and SMV and characterize the role of GmRPS8 in SMV infection in soybean. Expression analysis showed higher SMV-induced GmRPS8 expression levels in a susceptible soybean cultivar when compared with a resistant cultivar, suggesting that GmRPS8 was involved in the response to SMV in soybean. Subcellular localization showed that GmRPS8 was localized in the nucleus. Moreover, the yeast two-hybrid (Y2H) experiments showed that GmRPS8 only interacted with 6K1 among the eleven proteins encoded by SMV. The interaction between GmRPS8 and 6K1 was further verified by a bimolecular fluorescence complementation (BiFC) assay, and the interaction was localized in the nucleus. Furthermore, knockdown of GmRPS8 by a virus-induced gene silencing (VIGS) system retarded the growth and development of soybeans and inhibited the accumulation of SMV in soybeans. Together, these results showed that GmRPS8 interacts with 6K1 and contributes to soybean susceptibility to SMV. Our findings provide new insights for understanding the role of GmRPS8 in the SMV infection cycle, which could help reveal potyviral replication mechanisms. [ABSTRACT FROM AUTHOR]

Phytophthora root and stem rot (PRR) caused by an oomycete pathogen Phytophthora sojae is one of the most devastating and widespread diseases throughout soybean-producing regions worldwide. The diversity and variability of P. sojae races make effective control of the pathogen challenging. Here, we introduced an elicitor of plant defense response, the harpinXooc-encoding hrf2 gene from the rice bacterial pathogen Xanthomonas oryzae pv. oryzicola into soybean and evaluated resistance to P. sojae infection. Molecular analysis confirmed the integration and expression of hrf2 in the transgenic soybean. After inoculation with P. sojae, non-transformed control (NC) plants exhibited typical PRR symptoms, including necrotic and wilting leaves, and plant death, whereas most of the transgenic plants showed slightly chlorotic leaves and developed normally. Through T3 to T5 generations, the transgenic events displayed milder disease symptoms and had higher survival rates compared to NC plants, indicating enhanced and stable resistance to P. sojae infection, whereas without P. sojae inoculation, no significant differences in agronomic traits were observed between the transgenic and non-transformed plants. Moreover, after inoculation with P. sojae, significant upregulation of a set of plant defense-related genes, including salicylic acid- and jasmonic acid-dependent and hypersensitive response-related genes was observed in the transgenic plants. Our results indicate that hrf2 expression in transgenic soybean significantly enhanced resistance to P. sojae by eliciting multiple defense responses mediated by different signaling pathways. The potential functional role of the hrf2 gene in plant defense against P. sojae and other pathogens makes it a promising tool for broadening disease resistance in soybean. [ABSTRACT FROM AUTHOR]

Soybean oil contains approximately 20% oleic acid and 63% polyunsaturated fatty acids, which limits its uses in food products and industrial applications because of its poor oxidative stability. Increasing the oleic acid content in soybean seeds provides improved oxidative stability and is also beneficial to human health. Endoplasmic reticulum-associated delta-12 fatty acid desaturase 2 (FAD2) is the key enzyme responsible for converting oleic acid (18:1) precursors to linoleic acid (18:2) in the lipid biosynthetic pathway. In this study, a 390-bp conserved sequence of GmFAD2-1B was used to trigger a fragment of RNAi-mediated gene knockdown, and a seed-specific promoter of the β-conglycinin alpha subunit gene was employed to downregulate the expression of this gene in soybean seeds to increase the oleic acid content. PCR and Southern blot analysis showed that the T-DNA had inserted into the soybean genome and was stably inherited by the progeny. In addition, the expression analysis indicated that GmFAD2-1B was significantly downregulated in the seeds by RNAi-mediated post-transcription gene knockdown driven by the seed-specific promoter. The oleic acid content significantly increased from 20 to ~ 80% in the transgenic seeds, and the linoleic and linolenic acid content decreased concomitantly in the transgenic lines compared with that in the wild types. The fatty acid profiles also exhibited steady changes in three consecutive generations. However, the total protein and oil contents and agronomic traits of the transgenic lines did not show a significant difference compared with the wild types. [ABSTRACT FROM AUTHOR]

Key message: Robust RNAi-mediated resistance to multiple Potyvirus strains and isolates, but not to Secovirus BPMV, was conferred by expressing a short SMV P3 hairpin in soybean plants. Abstract: Engineering resistance to multiple Potyvirus strains is of great interest because of a wide variability of the virus strains, and mixed infections of multiple viruses or strains commonly associated with field grown soybean. In this study, RNAi-mediated silencing of the soybean mosaic virus (SMV) P3 cistron, which is reported to participate in virus movements and pathogenesis and to be the putative determinant of SMV virulence, was used to induce resistance to multiple Potyvirus strains and isolates in soybean. A 302 bp inverted repeat (IR) of the P3 cistron, isolated from the SMV strain SC3, was introduced into soybean. The transgenic lines exhibited stable and enhanced resistance to SMV SC3 under field conditions over 3 consecutive years. The transgenic lines also showed significantly enhanced resistance to four other SMV strains (SC7, SC15, SC18, and SMV-R, a novel recombinant found in China), the soybean-infecting bean common mosaic virus (BCMV) and watermelon mosaic virus (WMV). Nevertheless, no significant differences were found between transgenic plants and their non-transformed (NT) counterparts in terms of resistance to bean pod mottle virus (BPMV, Secoviridae). Consistent with the results of resistance evaluations, the expression of the respective viral CP cistrons and virus accumulation were significantly lower in seven Potyvirus strains and isolates than in the NT plants, but not in BCMV-inoculated transgenic lines. The results demonstrate the effectiveness of engineering resistance to multiple Potyvirus strains and isolates via RNAi-mediated SMV P3 cistron silencing, and thus provide an effective control strategy against Potyvirus infections in soybean and other crops. [ABSTRACT FROM AUTHOR]

Electron beam irradiation has been evaluated for the survival and reproduction of Liposcelis paeta Pearman (Psocoptera: Liposcelididae). All effects increased with increasing doses from 50 to 1000 Gy when the electron energy was 2 MeV. Eggs were unable to develop into adults following a dose of 100 Gy. Complete (100%) mortality was achieved about 5 weeks after adult emergence from nymphs irradiated at 300 Gy, whereas 100% mortality of adults was achieved 9 weeks after irradiation at 300 Gy. The fecundity was greatly reduced to 1.82% of that of control when L. paeta adults were irradiated at 250 Gy. A dose of 300 Gy caused complete reproductive sterility in adults. These results suggest that the most susceptible stage was the egg stage, then nymph and adult stages. A dose of 300 Gy is suggested for quarantine treatment of commodities infested by L. paeta. [ABSTRACT FROM AUTHOR]

Triacylglycerol (TAG), a main component of oil, is mainly biosynthesized by diacylglycerol acyltransferase (DGAT), which is critical for oil accumulation in plants. Intensive focus has been on DGAT2 functioning in unsaturated fatty acids biosynthesis. In this study, we analyzed the coding sequence (CDS) and amino acid sequence of GmDGAT2A and determined its key active sites through site-directed mutagenesis. As a consequence, H132, G201, and P152-X-I154-K155 were found to be essential active sites for GmDGAT2A. The spatial structure of the protein may bring the three active sites into close proximity, constituting an active domain. Additionally, N -terminus of GmDGAT2A was found to be an important regulator for the activity. Further, in vitro activity results uncovered GmDGAT2A was prone to utilize C18:2-CoA as the substrate. Consequently, overexpression of GmDGAT2A driven by a seed-specific promoter of Gmole1 in soybean significantly increased linoleic acid content specifically and total oil content, concomitant with accelerated elongation. ● An active center comprised of H132 and G201 as well as P152-X-I154-K155 was discovered in GmDGAT2A ● GmDGAT2A prefers to use C18:2-CoA as the substrate ● N -terminus auto inhibits GmDGAT2A activity ● Seed-specific over-expression of GmDGAT2A in soybean significantly elevated oil production and linoleic acid content [ABSTRACT FROM AUTHOR]

The leaves of soybean cultivar ZheA8901 show various symptoms (necrosis, mosaic, and symptomless) when infected with different strains of soybean mosaic virus (SMV). Based on a proteomic analysis performed with tandem mass tags (TMT), 736 proteins were differentially expressed from soybean samples that showed asymptomatic, mosaic, and necrosis symptoms induced by SMV strains SC3, SC7, and SC15, respectively. Among these, GmGSTU13 and ascorbate peroxidase (APX) were only upregulated in mosaic and symptomless leaves, respectively. The protein level of GmGSTU13 determined by western blot analysis was consistent with TMT analysis, and quantitative reverse transcriptase PCR analysis showed that GmGSTU13 mRNA levels in mosaic plants were 5.26- and 3.75-fold higher than those in necrotic and symptomless plants, respectively. Additionally, the expression of the viral coat protein ( CP ) gene was increased, and serious mosaic symptoms were observed in GmGSTU13 -overexpressing plants inoculated with all three SMV strains. These results showed that GmGSTU13 is associated with the development of SMV-induced mosaic symptoms in soybean and that APX is upregulated in symptomless leaves at both the transcriptional and protein levels. In APX gene-silenced soybean plants, the relative expression of the viral CP gene was 1.50, 7.59, and 1.30 times higher than in positive control plants inoculated with the three SMV strains, suggesting that the upregulation of APX may be associated with lack of symptoms in soybean infected with SMV. This work provides a useful dataset for identifying key proteins responsible for symptom development in soybean infected with different SMV strains.

Delta8 desaturase pathway, different from common delta6 desaturase pathway, is an alternate pathway of polyunsaturated fatty acids biosynthesis. Delta8-fatty acid desaturase is one of the key enzymes in delta8 desaturase pathway. Two specific fragments were separately cloned from genomic DNA and cDNA of Euglena gracilis by PCR with the primers designed according to the reported sequence. Comparison of the genomic and cDNA sequences revealed that there wasn't intron in this delta8-fatty acid desaturase gene. This gene has an open reading frame of 1 266 bp that encodes 421 amino acids. It is 6 bp longer than the reported gene sequence, and also showed certain difference from the reported sequence in the N-terminal. The recombinant expression plasmid pYEFD by subcloning delta8-fatty acid desaturase gene into the yeast-E. coli shuttle vector pYES2.0 was constructed and was transformed into the defective mutant INVSc1 of Saccharomyces cerevisiae by electrotransformation. The resulting strain YD8 harboring plasmid pYEFD was selected and was cultured in the induction medium with exogenous substrates omega6-eicosadienoic acid and omega3-eicosatrienoic acid for the expression of delta8-fatty acid desaturase gene. The results indicated that high level expressed As-fatty acid desaturase could convert omega6-eicosadienoic acid and omega3-eicosatrienoic acid to dihomo-gamma-linolenic acid and eicosatetraenoic acid with substrate conversion ratio 31.2% and 46.3%, respectively.