Sorghum is a feed/industrial crop in developed countries and a staple food elsewhere in the world. This study evaluated the sorghum mini core collection for days to 50% flowering (DF), biomass, plant height (PH), soluble solid content (SSC), and juice weight (JW), and the sorghum reference set for DF and PH, in 7–12 testing environments. We also performed genome-wide association mapping with 6 094 317 and 265 500 single nucleotide polymorphism markers in the mini core collection and the reference set, respectively. In the mini core panel we identified three quantitative trait loci for DF, two for JW, one for PH, and one for biomass. In the reference set panel we identified another quantitative trait locus for PH on chromosome 6 that was also associated with biomass, DF, JW, and SSC in the mini core panel. Transgenic studies of three genes selected from the locus revealed that Sobic.006G061100 (SbSNF4-2) increased biomass, 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. SbSNF4-2 and its orthologs will be valuable in genetic enhancement of biomass and sugar yield in plants.

Panicle morphology is an important trait in racial classification and can determine grain yield and other agronomic traits in sorghum. In this study, we performed association mapping of panicle length, panicle width, panicle compactness, and peduncle recurving in the sorghum mini core panel measured in multiple environments with 6,094,317 single nucleotide polymorphism (SNP) markers. We mapped one locus each on chromosomes 7 and 9 to recurving peduncles and eight loci for panicle length, panicle width, and panicle compactness. Because panicle length was positively correlated with panicle width, all loci for panicle length and width were colocalized. Among the eight loci, two each were on chromosomes 1, 2, and 6, and one each on chromosomes 8 and 10. The two loci on chromosome 2, i.e., Pm 2-1 and Pm 2-2, were detected in 7 and 5 out of 11 testing environments, respectively. Pm 2-2 colocalized with panicle compactness. Candidate genes were identified from both loci. The rice Erect Panicle2 (EP2) ortholog was among the candidate genes in Pm 2-2. EP2 regulates panicle erectness and panicle length in rice and encodes a novel plant-specific protein with unknown functions. The results of this study may facilitate the molecular identification of panicle morphology-related genes and the enhancement of yield and adaptation in sorghum.

Introduction: Sorghum plant color is the leaf sheath/leaf color and is associated with seed color, tannin and phenol content, head blight disease incidence, and phytoalexin production.Results: In this study, we evaluated plant color of the sorghum mini core collection by scoring leaf sheath/leaf color at maturity as tan, red, or purple across three testing environments and performed genome-wide association mapping (GWAS) with 6,094,317 SNPs markers.Results and Discussion: Eight loci, one each on chromosomes 1, 2, 4, and 6 and two on chromosomes 5 and 9, were mapped. All loci contained one to three candidate genes. In qPC5-1, Sobic.005G165632 and Sobic.005G165700 were located in the same linkage disequilibrium (LD) block. In qPC6, Sobic.006G149650 and Sobic.006G149700 were located in the different LD block. The single peak in qPC6 covered one gene, Sobic.006G149700, which was a senescence regulator. We found a loose correlation between the degree of linkage and tissue/organ expression of the underlying genes possibly related to the plant color phenotype. Allele analysis indicated that none of the linked SNPs can differentiate between red and purple accessions whereas all linked SNPs can differentiate tan from red/purple accessions. The candidate genes and SNP markers may facilitate the elucidation of plant color development as well as molecular plant breeding.

Landraces are ideal for identifying genes related to adaptation. The purpose of this study was to map and identify genes related to adaptation. We evaluated a mini core collection that broadly samples the global sorghum landrace gene pool for 11 traits in 4–12 environments. Association mapping with 6094 317 SNPs identified 70 loci for the 11 traits. The key findings include two panicle weight (PWt) and two grain yield (GY) loci overlapped, and two panicle length (PL) and two panicle width (PW) loci overlapped. Some loci for tiller number (TL), PL/PW, PWt, GY, and seed weight (SW) colocalized with previously mapped quantitative trait loci. We identified 33 candidate genes for TL, PL, PW, PWt, GY, SW, and MRC. The overlapping PWt and GY locus on chromosome 9 contained gibberellin receptor GID1 gene that regulates seed development. A TL locus on chromosome 1 that was consistently detected contained Sobic.001G152700 encoding a DUF1618 protein that was the sole horizontally transferred gene from sorghum to the parasitic Striga hermonthica, which was potentially related to environmental adaptation. These results are relevant for sorghum molecular breeding. Future studies are needed to functionally characterize the rich collection of novel candidate genes identified in this study. Key message We mapped 11 sorghum traits, identified 33 candidate genes, and found a grain yield gene ( GID1) that regulates seed development and a grass-specific tillering gene (DUF1618) transferred to Striga hermonthica.

Introduction: A whole plant can be regenerated through tissue culture from an embryogenic callus in a process referred to as plant regeneration. Regeneration ability of embryogenic callus is a quantitative trait and the main limiting factor for genetic studies in sorghum.Methods: We evaluated 236 sorghum mini core varieties for callus induction rate, embryogenic callus rate, callus browning rate and differentiation rate and performed a multi-locus genome-wide association study (GWAS) of the four traits with 6,094,317 SNPs.Results: We found five mini core varieties most amenable to tissue culture manipulations: IS5667, IS24503, IS8348, IS4698, and IS5295.Furthermore, we mapped 34 quantitative trait loci (QTLs) to the four traits and identified 47 candidate genes. Previous studies provided evidence for the orthologs of 14 of these genes for their role in cellular function and embryogenesis and that the ortholog of WIND1 (WOUND INDUCED DEDIFFERENTIATION 1) identified in this study promotes callus formation and increases de novo shoot regeneration.Conclusion: These candidate genes will help to further understand the genetic basis of plant embryonic callus regeneration.

Introduction: Water is essential for plant growth, and drought is one of the most predominant constraints on crop yield. Sorghum is a well-known drought-tolerant crop model, and sorghum landraces possess novel alleles for local adaptation.Methods: In this study, we evaluated a sorghum mini core panel of 239 landraces sampled globally for shoot and root growth under simulated drought conditions using 10% and 20% polyethylene glycol (PEG) in 2020 and 2024, and measured drought tolerance using the seedling tolerance coefficient (STC).Results and discussion: Phenotypic analysis showed that more accessions produced more roots than longer roots when exposed to 10% PEG; however, at 20% PEG, more accessions produced longer roots than more roots, reflecting the adaptability of some accessions to drought stress. However, PEG reduced shoot growth in all accessions in both years. A genome-wide association study (GWAS) on 32 growth and 19 STC traits identified 22 loci, 19 of which were mapped to the STC traits, and 17 of these 19 were associated with STC of shoot weight. Eleven of the 22 loci were collocated with 23 previously identified mapped drought-related quantitative trait loci (QTLs); 15 of these 23 QTLs were mapped to green leaf area, total number of green leaves, or chlorophyll content. We also found 19 candidate genes for 12 of the 22 loci. Five of those genes showed either preferential or specific expression in the roots according to GeneAtlas v2. One candidate gene from a locus colocated with a previously mapped chlorophyll fluorescence QTL has been shown to increase chlorophyll fluorescence in maize in another study. The results of this study lay the foundation for further characterizing the sorghum mini core panel for novel drought-tolerant genes.