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Main conclusion: A conserved cysteine residue (C266)-mediated homo-dimerization of SIE3 is required for the ubiquitination and degradation of SIP1 transcription factor in Lotus japonicas CTLH/CRA/RING-containing proteins have been shown to possess E3-ligase activities and are crucial for the regulation of numerous cellular signaling pathways. In our previous studies, SIE3 (SymRK-Interacting E3 ubiquitin ligase), a CTLH/CRA/RING-containing protein from Lotus japonicus, has been shown to associate with both Symbiosis Receptor Kinase (SymRK) and SIP1 (SymRK interacting protein 1) transcription factor, and ubiquitinate SymRK (Yuan et al. Plant Physiol 160 (1):106–117, 2012; Feng et al. Front Plant Sci 11: 795, 2020). Besides, we previously also demonstrated that the residue, cysteine-266 in the CRA (CT11-RanBPM) domain is required for homodimerization of SIE3 and cysteine-266 residue-mediated homodimerization is important for the symbiosic function of SIE3 (Feng et al. 2020). In this report, SIE3 was shown to induce the ubiquitination and degradation of SIP1. The cysteine-266 residue is essential for the E3-ligase activity and is highly conserved in the SIE3-like proteins. Our works refined the working model that homodimerization of SIE3 is required for ubiquitin-related degradation of SIP1 and found a conserved cysteine residue plays a key role in the activity of a plant dimeric E3 ligase. [ABSTRACT FROM AUTHOR]

Cystathionine-β-synthase (CBS) domain-containing proteins (CDCPs) constitute a large family in plants, and members of this family have been implicated in a variety of biological processes. However, the precise functions and the underlying mechanisms of most members of this family in plants remain to be elucidated. CBSDUF proteins belong to the CDCP superfamily, which contains one domain of unknown function (DUF21) and an N terminus that is adjacent to two intracellular CBS domains. In this study, a comprehensive genome database analysis of soybean was performed to investigate the role(s) of these CBSDUFs and to explore their nomenclature, classification, chromosomal distribution, exon–intron organization, protein structure, and phylogenetic relationships; the analysis identified a total of 18 putative CBSDUF genes. Using specific protein domains and phylogenetic analysis, the CBSDUF gene family was subdivided into eight groups. The soybean CBSDUF genes showed an uneven distribution on 12 chromosomes of Glycine max. RNA-seq transcriptome data from different tissues in public databases revealed tissue-specific and differential expression profiles of the GmCBSDUFs, and qPCR analysis revealed that certain groups of soybean CBSDUFs are likely involved in specific stress responses. In addition, GmCBSDUF3 transgenic Arabidopsis was subjected to phenotypic analysis under NaCl, PEG, and ABA stress treatments. The overexpression of GmCBSDUF3 could enhance tolerance to drought and salt stress in Arabidopsis. This study presents a first comprehensive look at soybean CBSDUF proteins and provides valuable resources for functionally elucidating this protein subgroup within the CBS domain-containing protein family. [ABSTRACT FROM AUTHOR]

Key message: Drought tolerance level of 136 soybean genotypes, the correlations among traits were evaluated, and several important drought-tolerant genotypes, traits, SNPs and genes were possibly useful for soybean genetic breeding. Drought is an adverse environmental factor affecting crops growth, development, and yield. Promising genotypes and genes with improved tolerance to drought are probably effective ways to alleviate the situation. In this study, our main task was to determine drought tolerance level of 136 soybean genotypes, the correlations among physiological and agronomic traits under drought, and drought-tolerant single nucleotide polymorphism (SNPs) and genes. In this study, twenty-six varieties were identified as excellent tolerant genotypes to stress among which S14, S93 and S135 with high drought-tolerant index (DTI > 1.3) and yield (Y > 300 kg). Fourteen varieties were identified as drought-sensitive genotypes, such as S25, S45 and S58, with low drought-tolerant index (DTI < 0.5). 422 SNPs and 302 genes correlated with seed number per plant (SNPP), maturity (M), number of seeds per pod (NSPP), node number of main stem (NNMS), Stem diameter (SD) and pull stem (PS) were detected under well-watered and drought conditions by genome-wide association study (GWAS). Among them, we found SNPs (Chr 3:1758920-1958934) between drought-tolerant and sensitive genotypes. 13 genes (Glyma.03G017800, Glyma.03G018000, Glyma.03G018200, Glyma.03G018400, Glyma.03G018500, Glyma.03G018600, Glyma.03G018700, Glyma.03G018800, Glyma.03G018900, Glyma.03G019000, Glyma.03G019100, Glyma.03G019200, Glyma.03G019300) correlated with NNMS were detected. By qRT-PCR, the expression level of Glyma.03G018000 and Glyma.03G018900 in drought-tolerant varieties was significantly increased, but low or no expression in sensitive varieties under drought stress. This study provides important drought-tolerant genotypes, traits, SNPs and potential genes, possibly useful for soybean genetic breeding. [ABSTRACT FROM AUTHOR]

Lodging is one of the major influencing factors of yield and quality in soybean [ Glycine max (L.) Merr.] and other crops. To dissect the genetic basis of lodging in soybean, a recombinant inbred line population consisting of 165 lines was used to evaluate lodging percentage and eight related traits (branch number, internode length, number of nodes, plant height, stem diameter, stem strength, root length, and root weight) in three environments. Regression analysis indicated that plant height and root weight, which explain more than 55% of the variation in lodging percentage, might be the key factors influencing lodging in soybean. Nine consensus quantitative trait locus (QTLs) of lodging percentage were detected in one to three environments. Of which, eight consensus QTLs were colocated with 16 consensus QTLs of lodging-related traits by meta-analysis. In addition, seven candidate genes with the biological functions of shoot branching, root development, internode elongation, and lignin biosynthesis were identified on four pleiotropic QTL regions ( oq.13-1, oq.13-2, oq.19-2, and oq.19-3) for lodging percentage and related traits. These findings showed that the consensus QTLs of lodging percentage might result from the pleiotropic QTLs affecting the lodging-related traits. Soybean lodging is determined by the cumulative effect of many traits/processes of growth and development. The combination of MAS, statistical model, and phenotypic selection will provide a powerful breeding strategy for lodging resistance in soybean. [ABSTRACT FROM AUTHOR]

Key message: In this study, Rpp6907, a novel resistance gene/allele to Phakopsora pachyrhizi in soybean, was mapped in a 111.9- kb region, including three NBS-LRR type predicted genes, on chromosome 18. Abstract: Soybean rust caused by Phakopsora pachyrhizi Sydow has been reported in numerous soybean-growing regions worldwide. The development of rust-resistant varieties is the most economical and environmentally safe method to control the disease. The Chinese soybean germplasm SX6907 is resistant to P. pachyrhizi and exhibits immune reaction compared with the known Rpp genes. These characteristics suggest that SX6907 may carry at least one novel Rpp gene/allele. Three F populations from the crosses of SX6907 (resistant) and Tianlong 1, Zhongdou40, and Pudou11 (susceptible) were used to map the Rpp gene. Three resistance responses (immune, red-brown, and tan-colored lesion) were observed from the F individuals. The segregation follows a ratio of 1(resistance):2(heterozygous):1(susceptible), indicating that the resistance in SX6907 is controlled by a single incomplete dominant gene (designated as Rpp6907). Results showed that Rpp6907 was mapped on soybean chromosome 18 (molecular linkage group G, MLG G) flanked by simple sequence repeat (SSR) markers SSR24 and SSR40 at a distance of 111.9 kb. Among the ten genes marked within this 111.9-kb region between the two markers, three genes ( Glyma18g51930, Glyma18g51950, and Glyma18g51960) are nucleotide-binding site and leucine-rich repeat-type genes. These genes may be involved in recognizing the presence of pathogens and ultimately conferring resistance. Based on resistance spectrum analysis and mapping results, we inferred that Rpp6907 is a novel gene different from Rpp1 in PI 200492, PI 561356, PI 587880A, PI 587886, and PI 594538A, or a new Rpp1- b allele. [ABSTRACT FROM AUTHOR]