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Summary: Salt stress is a major challenge that has a negative impact on soybean growth and productivity. Therefore, it is important to understand the regulatory mechanism of salt response to ensure soybean yield under such conditions.In this study, we identified and characterized a miR160a–GmARF16–GmMYC2 module and its regulation during the salt–stress response in soybean.miR160a promotes salt tolerance by cleaving GmARF16 transcripts, members of the Auxin Response Factor (ARF) family, which negatively regulates salt tolerance. In turn, GmARF16 activates GmMYC2, encoding a bHLH transcription factor that reduces salinity tolerance by down‐regulating proline biosynthesis. Genomic analysis among wild and cultivated soybean accessions identified four distinct GmARF16 haplotypes. Among them, the GmARF16H3 haplotype is preferentially enriched in localities with relatively saline soils, suggesting GmARF16H3 was artificially selected to improve salt tolerance.Our findings therefore provide insights into the molecular mechanisms underlying salt response in soybean and provide valuable genetic targets for the molecular breeding of salt tolerance. [ABSTRACT FROM AUTHOR]

Summary: Large structural variations frequently occur in higher plants; however, the impact of such variations on plant diversification, adaptation and domestication remains elusive.Here, we mapped and characterised a reciprocal chromosomal translocation in soybeans and assessed its effects on diversification and adaptation of wild (Glycine soja) and semiwild (Glycine gracilis) soybeans, and domestication of cultivated soybean (Glycine max), by tracing the distribution of the translocation in the USDA Soybean Germplasm Collection and population genetics analysis.We demonstrate that the translocation occurred through CACTA transposon‐mediated chromosomal breakage in wild soybean c. 0.34 Ma and is responsible for semisterility in translocation heterozygotes and reduces their reproductive fitness. The translocation has differentiated Continental (i.e. China and Russia) populations from Maritime (i.e. Korea and Japan) populations of G. soja and predominately adapted to cold and dry climates. Further analysis revealed that the divergence of G. max from G. soja predates the translocation event and that G. gracilis is an evolutionary intermediate between G. soja and G. max.Our results highlight the effects of a chromosome rearrangement on the processes leading to plant divergence and adaptation, and provides evidence that suggests G. gracilis, rather than G. soja, as the ancestor of cultivated soybean. [ABSTRACT FROM AUTHOR]

Brassinosteroids (BRs) regulate many physiological processes during plant development, including flowering. However, little is known about the components of BR signaling that mediate flowering. Here, we report that BRASSINAZOLE-RESISTANT1 (BZR1), the conformation of which is altered by a cyclophilin (CYP20-2), binds cis -elements in the FLOWERING LOCUS D (FLD) promoter to regulate flowering. Both bzr1-1D and fld-4 showed delayed flowering. Electrophoretic mobility shift assay and chromatin immunoprecipitation revealed that BZR1 bound to a putative BR response cis -element and suppressed the expression of FLD. Overexpression of FLD partially rescued the late flowering of pBZR1 : mBZR1Pro234-Leu-CFP (mx3). Yeast two-hybrid and pull-down assays demonstrated that BZR1 interacts with CYP20-2. Arabidopsis thaliana CYP20-2 had greater peptidyl-prolyl cis-trans isomerase activity than did wheat (Triticum aestivum) CYP20-2. Fourier transform infrared spectroscopy revealed conformation changes in BZR1, dependent on interaction with CYP20-2. Due to differences in activity and substrate preference between CYP20-2 proteins from wheat and Arabidopsis , At -CYP20-2 –overexpressing lines showed earlier flowering, whereas Ta CYP20-2 lines flowered later. Immunoblot and chromatin immunoprecipitation assays showed that histone H3 trimethyl Lys4 and H3 acetylation levels were negatively correlated with the transcription of FLD (a putative histone demethylase) in various lines. Therefore, a conformational change of BZR1 mediated by CYP20-2 causes altered flowering through modulation of FLD expression. [ABSTRACT FROM AUTHOR]

WUSCHEL (WUS) is essential for preventing stem cell differentiation in Arabidopsis. Here we report that in addition to its functions in meristematic stem cell maintenance, WUS is involved in the regulation of cell division. The WUS gain-of-function mutant, stem ectopic flowers (sef), displayed elongated hypocotyls, whereas the loss-of-function wus-1 mutant had shortened hypocotyls. The long hypocotyl in sef was due to the presence of more cells, rather than increased cell elongation. Microscopic observation, flow cytometry assays, quantitative RT-PCR (qRT-PCR), and histochemical staining of CycB1;1::GUS supported the hypothesis that ectopic cell division occurred in the sef hypocotyls after germination. Both immunoblot and qRT-PCR results showed that WUS was ectopically expressed in sef hypocotyls. Luciferase activity, chromatin immunoprecipitation (ChIP) and electrophoretic mobility shift assay (EMSA) showed that GLUTAMINE-RICH PROTEIN 23 (GRP23) expression can be activated by WUS and that GRP23 is a direct target gene of WUS. The phenotypes of 35S::GRP23 plants and GRP23 knockdown lines supported the notion that GRP23 mediates the effects of WUS on hypocotyl length. Together, our data suggest that ectopic expression of WUS in hypocotyl controls cell division through its target gene GRP23. [ABSTRACT FROM AUTHOR]

WUSCHEL (WUS) is essential for preventing stem cell differentiation in Arabidopsis. Here we report that in addition to its functions in meristematic stem cell maintenance, WUS is involved in the regulation of cell division. The WUS gain-of-function mutant, stem ectopic flowers (sef), displayed elongated hypocotyls, whereas the loss-of-function wus-1 mutant had shortened hypocotyls. The long hypocotyl in sef was due to the presence of more cells, rather than increased cell elongation. Microscopic observation, flow cytometry assays, quantitative RT-PCR (qRT-PCR), and histochemical staining of CycB1;1::GUS supported the hypothesis that ectopic cell division occurred in the sef hypocotyls after germination. Both immunoblot and qRT-PCR results showed that WUS was ectopically expressed in sef hypocotyls. Luciferase activity, chromatin immunoprecipitation (ChIP) and electrophoretic mobility shift assay (EMSA) showed that GLUTAMINE-RICH PROTEIN 23 (GRP23) expression can be activated by WUS and that GRP23 is a direct target gene of WUS. The phenotypes of 35S::GRP23 plants and GRP23 knockdown lines supported the notion that GRP23 mediates the effects of WUS on hypocotyl length. Together, our data suggest that ectopic expression of WUS in hypocotyl controls cell division through its target gene GRP23. [ABSTRACT FROM AUTHOR]