Sorghum is feed/industrial crop in the developed countries and a staple food in the rest of the world. In this study, we evaluated the sorghum mini core (MC) collection for days to 50% flowering (DF), biomass (BM), plant height (PH), soluble solid content (SSC) and juice weight (JW) and the sorghum reference set (RS) for DF and PH in 7-12 testing environments and performed association mapping with 6,094,317 SNP markers in the MC and 265,500 SNPs for the RS. We identified in the MC panel three QTLs for DF, one for PH, one for BM, and two for JW. In the RS panel we identified another PH QTL on chromosome 6 also associated with DF, BM, JW, and SSC in the MC panel. Transgenic studies of three genes selected from the locus revealed that Sobic.006G061100 (SbSNF4-2) increased BM, SSC, JW, and PH when overexpressed in both sorghum and sugarcane and delayed flowering in transgenic sorghum. SbSNF4-2 encodes a γ subunit of the evolutionarily conserved AMPK/SNF1/SnRK1 heterotrimeric complexes and overexpression of human or mouse γ2 in heart or the whole body also increases heart or body biomass. SbSNF4-2 and its orthologs will be valuable in genetic enhancement of biomass and sugar yield in plants.

Significant progress has been made on sorghum transformation in the last decades; however, the transformation process has been constrained by the availability of immature embryos because most of the researchers have utilized immature embryos as favorable explants. Although immature embryos have been proven to be optimal for tissue culture and transformation, isolation of immature embryos is time-consuming, labor-intensive, and limited by warm weather. In this study, we developed an efficient genetic transformation system using mature seeds as explants. The nptII and gus gene, used as the selective marker and report gene respectively, have been co-transformed by particle bombardment. After optimization of tissue culture, the G418 concentration, and transgenic, the average transformation frequency at 13.33% was achieved routinely. The transgenic events and transgene copy numbers were determined by PCR and RT-PCR, respectively. The geneticin selection and GUS staining on T1 seedlings confirmed that the transgenic plants were heritable. Our results demonstrated that the efficient sorghum transformation system has been established using mature seeds as explants. This transformation system will promote sorghum research on genetic engineering and genome editing without seasonal weather conditions restriction and explant resources restriction.

Sorghum-sudanense is a hybrid of sorghum and Sudanese grass and is widely used in animal husbandry and aquaculture because of its high yield, excellent quality and wide adaptability. Using high-throughput sequencing, we constructed a high-density genetic map of sorghum Tx623A Â sudangrass S722 with 103 recombinant inbred lines (RILs) in this study and mapped quantitative trait loci (QTLs) for plant height (PH), stem diameter (SD), tiller number (TN), fresh weight (FW) and dry weight per plant (DW). The map included 1610 markers with a total length of 2329 cM and QTL mapping identified 19 QTLs, including two for PH, three for SD, four for TN, four for FW and five for DW. We detected two QTL clusters containing overlapping QTLs for PH, FW and DW. Orthologs of three SD candidate genes from maize were found within two SD QTLs. The identification of these QTLs will be useful for cloning the corresponding genes for these traits and developing marker-assisted selection (MAS) in future sorghum breeding programs.

Melilotus officinalis is an important legume crop with forage and Chinese medicinal value. The unknown genome of M. officinalis restricted the domestication and utilization of the species and its germplasm resource diversity. A chromosome‐scale assembly of the M. officinalis genome was assembled and analysed. The 976.27 Mb of genome was divided into eight chromosomes covering 99.16% of the whole genome. A total of 50022 genes were predicted in the genome. M. officinalis and Melilotus albus shared a common ancestor 0.5–5.65 million years ago (MYA). A genome‐wide doubling event occurred 68.93 MYA according to the synonymous nucleotide‐substitution values. A total of 552102 tandem repeats were predicted, and 46004 SSR primers of TRs with 10 or more base pairs were developed and designed. The elucidation of the M. officinalis genome provides a compelling model system for studying the genetic, evolutionary and biosynthesis of this legume.