Modulation of evening complex activity enables north-to-south adaptation of soybean

Soybean,a typical short-day crop,is sensitive to photoperiod,which is a major limiting factor defining its north-to-south cultivation range.The long-juvenile(LJ)trait is controlled primarily by the J locus which has been used for decades by soybean breeders to delay flowering and improve grain yield in tropical regions.The J gene encodes an ortholog of the Arabidopsis Evening Complex(EC)component EARLY FLOWERING 3(ELF3).To identify modifiers of J,we conducted a forward genetic screen and isolated a mutant(eoj57)that in combination with j has longer flowering delay compared with j single mutant plants.Map-based cloning and genome re-sequencing identified eoj57(designated as GmLUX2)as an ortholog of the Arabidopsis EC component LUX ARRHYTHMO(LUX).To validate that GmLUX2 is a modifier of J,we used trans-complementation and identified a natural variant allele with a similar phenotype.We also show that GmLUX2 physically interacts with GmELF3a/b and binds DNA,whereas the mutant and natural variant are attenuated in both activities.Transcriptome analysis shows that the GmLUX2-GmELF3a complex co-regulates the expression of several circadian clock-associated genes and directly represses E1 expression.These results provide mechanistic insight into how GmLUX2-GmELF3 controls flowering time via synergistic regulation of gene expression.These novel insights expand our understanding of the regulation of the EC complex,and facilitate the development of soybean varieties adapted for growth at lower latitudes.

Whole-genome resequencing of the wheat A subgenome progenitor Triticum urartu provides insights into its demographic history and geographic adaptation

Triticum urartu is the progenitor of the A subgenome in tetraploid and hexaploid wheat.Uncovering the landscape of genetic variations in T.urartu will help us understand the evolutionary and polyploid characteristics of wheat.Here,we investigated the population genomics of T.urartu by genome-wide sequencing of 59 representative accessions collected around the world.A total of 42.2 million highquality single-nucleotide polymorphisms and 3 million insertions and deletions were obtained by mapping reads to the reference genome.The ancient T.urartu population experienced a significant reduction in effective population size(Ne)from3000000 to140000 and subsequently split into eastern Mediterranean coastal and Mesopotamian-Transcaucasian populations during the Younger Dryas period.A map of allelic drift paths displayed splits and mixtures between different geographic groups,and a strong genetic drift towards hexaploid wheat was also observed,indicating that the direct donor of the A subgenome originated from northwestern Syria.Genetic changes were revealed between the eastern Mediterranean coastal and Mesopotamian-Transcaucasian populations in genes orthologous to those regulating plant development and stress responses.A genome-wide association study identified two single-nucleotide polymorphisms in the exonic regions of the SEMI-DWARF 37 ortholog that corresponded to the different T.urartu ecotype groups.Our study provides novel insights into the origin and genetic legacy of the A subgenome in polyploid wheat and contributes a gene repertoire for genomicsenabled improvements in wheat breeding.

The ties of brotherhood between japonica and indica rice for regional adaptation

Selection of beneficial genomic variants was crucial for regional adaptation of crops during domestication,but the underlying genomic basis remains largely unexplored.Here we report a genome-wide selective-sweep analysis of 655 japonica and 1,205 indica accessions selected from 2,673 landraces through principal component analysis to identify 5,636 non-synonymous single nucleotide polymorphisms(SNPs)fixed in at least one subspecies.We classified these SNPs into three groups,jiS(japonica-and indica-selected),jS(japonica-selected only),and iS(indica-selected only),and documented evidence for selection acting on these groups,their relation to yield-related traits,such as heading date,and their practical value in cropping area prediction.We also demonstrated the role of a jiS-SNP-containing gene in temperature adaptability.Our study informs genes underpinning adaptation that may shape Green Super Rice and proposes a time-saving,cost-reducing selection strategy of genomic breeding,sweep-SNP-guided selection,for developing regionally-adapted heterosis.