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Sorghum [Sorghum bicolor (L.) Moench] is a potential crop for organic production that could help meet the demand increase in organic food products and feed grains, but no efforts have been made to improve sorghum breeding tools, techniques, and methods for this cropping system. Based on revelations in other crops, focal traits and their prioritization to optimize sorghum for organic use likely differs from conventional sorghum breeding targets. This study evaluated yield performance, agronomic characteristics, and biotic stress resistance under certified organic practices in a range of grain sorghum genotypes that included 70 hybrids, 72 advanced breeding lines, and 43 diverse accessions, as well as 10 sweet sorghum cultivars and four commercial maize hybrids. Multiyear, multilocation trial data demonstrated that sorghum can be effectively produced using sustainable and organic inputs, but hybrid or cultivar selection is extremely important for success as entry means for grain yield ranged from 26 to 5,970 kg ha−1. Yields of top sorghum entries rivaled commercially available maize (Zea mays) hybrids. Overall, hybrids significantly outperformed inbred lines as heterosis proved beneficial for influential agronomic traits, although a Clemson F6 advanced breeding line, PV20_0426, ranked second in yield. Sugarcane aphid tolerance, increased canopy closure, and grain mold resistance were positively correlated with grain yield and should be considered target traits for breeding sorghum hybrids and cultivars for organic use. Depending on possible seed production constraints, developing pure line cultivars with the proper trait package may be effective to diminish this potential obstacle for the organic sorghum market. Core Ideas: Sorghum can be effectively produced using sustainable and organic inputs.Sorghum hybrid or cultivar selection is extremely important for success.Yields of top grain sorghum entries rivaled commercially available organic maize hybrids.Hybrids significantly outperformed inbred lines as heterosis was evident for multiple traits.Increased canopy closure along with sugarcane aphid and grain mold resistance serve as target traits. [ABSTRACT FROM AUTHOR]

ABSTRACT Phenotypic plasticity is the property of a genotype to produce different phenotypes under different environmental conditions. Understanding genetic and environmental factors behind phenotypic plasticity helps answer some longstanding biology questions and improve phenotype prediction. In this study, we investigated the phenotypic plasticity of flowering time and plant height with a set of diverse sorghum lines evaluated across 14 natural field environments. An environmental index was identified to quantitatively connect the environments. Reaction norms were then obtained with the identified indices for genetic dissection of phenotypic plasticity and performance prediction. Genome‐wide association studies (GWAS) detected different sets of loci for reaction‐norm parameters (intercept and slope), including 10 new genomic regions in addition to known maturity (Ma1) and dwarfing genes (Dw1, Dw2, Dw3, Dw4 and qHT7.1). Cross‐validations under multiple scenarios showed promising results in predicting diverse germplasm in dynamic environments. Additional experiments conducted at four new environments, including one from a site outside of the geographical region of the initial environments, further validated the predictions. Our findings indicate that identifying the environmental index enriches our understanding of gene‐environmental interplay underlying phenotypic plasticity, and that genomic prediction with the environmental dimension facilitates prediction‐guided breeding for future environments. [ABSTRACT FROM AUTHOR]

Multiparent advanced eneration inter-cross (MAGIC) populations improve the precision of quantitative trait loci (QTL) mapping over biparental populations by incorporating increased diversity and opportunities to reduce linkage disequilibrium among variants. Here, we describe the development of a MAGIC B-Line (MBL) population from an inter-cross among 4 diverse founders of grain sorghum [Sorghum bicolor (L.) Moench] across different races (kafir, guinea, durra, and caudatum). These founders were selected based on genetic uniqueness and several distinct qualitative features including panicle architecture, plant color, seed color, endosperm texture, and awns. A whole set of MBL (708 F6) recombinant inbred lines along with their founders were genotyped using Diversity Arrays Technology (DArTseq) and 5,683 single-nucleotide polymorphisms (SNPs) were generated. A genetic linkage map was constructed using a set of polymorphic, quality-filtered markers (2,728 SNPs) for QTL interval-mapping. For population validation, 3 traits (seed color, plant color, and awns) were used for QTL mapping and genome-wide association study (GWAS). QTL mapping and GWAS identified 4 major genomic regions located across 3 chromosomes (Chr1, Chr3, and Chr6) that correspond to known genetic loci for the targeted traits. Founders of this population consist of the fertility maintainer (A/B line) gene pool and derived MBL lines could serve as female/seed parents in the cytoplasmic male sterility breeding system. The MBL population will serve as a unique genetic and genomic resource to better characterize the genetics of complex traits and potentially identify superior alleles for crop improvement efforts to enrich the seed parent gene pool. [ABSTRACT FROM AUTHOR]

Hybrid breeding in sorghum [Sorghum bicolor (L.) Moench] utilizes the cytoplasmic-nuclear male sterility (CMS) system for seed production and subsequently harnesses heterosis. Since the cost of developing and evaluating inbred and hybrid lines in the CMS system is costly and time-consuming, genomic prediction of parental lines and hybrids is based on genetic data genotype. We generated 602 hybrids by crossing two female (A) lines with 301 diverse and elite male (R) lines from the sorghum association panel and collected phenotypic data for agronomic traits over two years. We genotyped the inbred parents using whole genome resequencing and used 2,687,342 high quality (minor allele frequency > 2%) single nucleotide polymorphisms for genomic prediction. For grain yield, the experimental hybrids exhibited an average mid-parent heterosis of 40%. Genomic best linear unbiased prediction (GBLUP) for hybrid performance yielded an average prediction accuracy of 0.76-0.93 under the prediction scenario where both parental lines in validation sets were included in the training sets (T2). However, when only female tester was shared between training and validation sets (T1F), prediction accuracies declined by 12-90%, with plant height showing the greatest decline. Mean accuracies for predicting the general combining ability of male parents ranged from 0.33 to 0.62 for all traits. Our results showed hybrid performance for agronomic traits can be predicted with high accuracy, and optimizing genomic relationship is essential for optimal training population design for genomic selection in sorghum breeding. [ABSTRACT FROM AUTHOR]