Sorghum Improvement Research Articles

The Genetic Diversity of 69 Widely Used Chinese Sorghum Hybrids Released between the 1970s and 2010s

Sorghum has a long history of cultivation in China. In this study, we aimed to clarify the genetic relationships and genetic variation trends in widely used Chinese sorghum hybrids which were released from the 1970s to 2010s and attempted to analyze the changes in sorghum breeding. A total of 257 alleles were detected by 51 polymorphic SSR markers among 69 widely used hybrids; an average of 5.04 alleles were detected by each marker. The average Shannon’s index and polymorphism information content (PIC) of markers were 1.39 and 0.70, respectively. Nei’s genetic diversity index continuously increased in four different breeding development stages (1973–1982, 1983–1992, 1993–2002, and 2003–2014). Genetic diversity gradually increased among the sorghum hybrids. Genetic similarity coefficients in the four breeding development stages first showed an increasing trend, and then a decreasing trend, finally stabilizing with an average value of 0.65. The genetic similarity changes in hybrids in early and late maturing areas were consistent at different breeding development stages. The genetic similarity coefficients in late maturing areas were constantly higher than those in the early maturing areas. This is related to China’s creative utilization of A2 cytoplasmic male sterile materials in the 1990s. A cluster analysis determined that 69 hybrids were divided into two groups, A and B. Group A could be further subdivided into four subgroups. These findings could provide a reference for parental selection and hybrid breeding in sorghum improvement programs.

Identification of superior genotypes for leaf architecture traits in Sorghum bicolor through GGE biplot analysis

Context Well-organised leaf architecture produces compact canopies and allows for greater sunlight penetration, higher photosynthetic rates, and thus greater yields. Breeding for enhanced leaf architecture of sorghum (Sorghum bicolor L.), a key food source in semi-arid regions, benefits its overall production. Aims The study focuses on selecting useful genotypes with excellent leaf architecture for grain sorghum improvement. Methods In total, 185 sorghum genotypes were subjected to multi-environment trials. Leaf flagging-point length, leaf length, leaf width, leaf angle and leaf orientation value (LOV) were characterised under field conditions. Genotype + genotype × environment interaction (GGE) biplot analysis was used to identify the most stable genotypes with the highest LOV. Key results Statistical analysis showed significant effects of genotype × environment interaction (P < 0.001), and high broad-sense heritability for the traits. Correlation analysis demonstrated negative correlations (P < 0.001) between LOV and its components. Singular value decomposition of LOVs in the first two principal components explained 89.19% of the total variation. GGE biplot analysis identified G55 as the ideotype with the highest and most stable LOV. Conclusions Leaf architecture optimisation should be given greater attention. This study has identified a genotype with optimal and stable leaf architecture, laying the foundation for improvement in breeding to increase overall yields of sorghum. Implications Genotype G55 can be utilised as a parent with other parents that display economically important characteristics in breeding programs to produce offspring that can be planted densely to increase population yields. Genotypes identified with loose leaf architecture are useful in dissecting genes controlling leaf architecture by crossing with G55 to construct genetic mapping populations.

Complete telomere-to-telomere assemblies of two sorghum genomes to guide biological discovery.

The assembly of two sorghum T2T genomes corrected the assembly errors in the current reference, uncovered centromere variation, boosted functional genomics research, and accelerated sorghum improvement.

Functional insight into multi-omics-based interventions for climatic resilience in sorghum (Sorghum bicolor): a nutritionally rich cereal crop.

Thearticle highlights omics-based interventions in sorghum to combat food and nutritional scarcity in the future. Sorghum with its unique ability to thrive in adverse conditions, has become a tremendous highly nutritive, and multipurpose cereal crop. It is resistant to various types of climatic stressors which will pave its way to a future food crop. Multi-omics refers to the comprehensive study of an organism at multiple molecular levels, including genomics, transcriptomics, proteomics, and metabolomics. Genomic studies have provided insights into the genetic diversity of sorghum and led to the development of genetically improved sorghum. Transcriptomics involves analysing the gene expression patterns in sorghum under various conditions. This knowledge is vital for developing crop varieties with enhanced stress tolerance. Proteomics enables the identification and quantification of the proteins present in sorghum. This approach helps in understanding the functional roles of specific proteins in response to stress and provides insights into metabolic pathways that contribute to resilience and grain production. Metabolomics studies the small molecules, or metabolites, produced by sorghum, provides information about the metabolic pathways that are activated or modified in response to environmental stress. This knowledge can be used to engineer sorghum varieties with improved metabolic efficiency, ultimately leading to better crop yields. In this review, we have focused on various multi-omics approaches, gene expression analysis, and different pathways for the improvement of Sorghum. Applying omics approaches to sorghum research allows for a holistic understanding of its genome function. This knowledge is invaluable for addressing challenges such as climate change, resource limitations, and the need for sustainable agriculture.

Characterization of Coloured Sorghum Genotypes for Qualitative and Quantitative Characters

The experiment was conducted at College of Agriculture, Raichur, University of Agricultural Sciences, Raichur, Karnataka, India during October 2021–Februrary 2022 to characterize the 100-coloured sorghum genotypes along with four checks viz., M 35-1, AKJ 1, Paiyur 2 and GS-23 for eight qualitative characters and 10 quantitative characters in an augmented block design. The results revealed that, majority of the genotypes exhibited the pigmented stem (93%) and leaves almost green (61%) at harvest, horizontal flag leaf orientation (100%), loose erect primary branches of panicle (38%), black glumes (58%), red grain colour (36%), circular grain shape (75%) and freely threshable (93%) characters. For all the quantitative characters studied, a wide range of variation was observed. For stay green character, genotype IS 21868 showed completely green leaves. Similarly, for other characters also superior genotypes were identified in this study. Such genotypes can be used further in improvement of sorghum for its grain yield. For grain yield, 14 genotypes exhibited higher yields when compared to the best check GS-23, viz., IS 29032 (120.0 g), IS 6508 (119.18 g), IS 16006 (113.80 g), IS 28065 (102.88 g), IS 23890 (94.88 g), IS 28049 (94.28 g), IS 23865 (89.48 g), IS 29031 (87.98), IS 28202 (87.88), IS 31706 (86.48), IS 2582 (85.88 g), IS 28200 (83.58), IS 16398 (81.08 g) and IS 23955 (80.0 g). Eight genotypes were on par with GS-23. These genotypes can be further evaluated for its yield stability within and across locations.

Bulk Segregant Analysis for the Identification of Shoot Fly Resistance Linked Molecular Marker in Sorghum [Sorghum bicolor (L.) Moench

Sorghum (Sorghum bicolor (L.) Moench) is one of the most important crops in the semi-arid regions of the world. One of the important biotic constraints to sorghum production in India is the shoot fly which attacks sorghum at the seedling stage. The study was undertaken during 2021–22 at the Centre for Millets Research, Sardarkrushinagar Dantiwada Agricultural University, Deesa, Gujarat, India to assess linked molecular markers for sorghum shoot fly resistance using the bulk segregant analysis (BSA) method with simple sequence repeat (SSR) marker from developed F2 mapping population with two genetically diverse parental lines, SWARNA (susceptible to shoot fly) and IS 18551 (resistant to shoot fly). Sixty-five SSRs primers pair were used for the parental polymorphism survey using two contrasting parents to detect the primers exhibiting polymorphism. Eight out of sixty-five primers showed polymorphism (12.30%) between two contrasting parental lines in sorghum. Two out of eight polymorphic SSRs primer pairs i.e., Xtxp 67 and Xgap 88 were found polymorphic between resistance and susceptibility in parents and bulks and thus reported to be putatively linked with shoot fly. Bulk segregant analysis (BSA) was extended to identify the traits controlled by minor genes with additive effects, which increased the power and efficiency of this molecular technique to construct genetic map in the sorghum crop improvement program. The identified SSRs markers i.e., Xtxp 67 and Xgap 88 might be useful to screen resistance for shoot fly infestation in future sorghum improvement program.

Genetic diversity, population structure and anthracnose resistance response in a novel sweet sorghum diversity panel.

Sweet sorghum is an attractive feedstock for the production of renewable chemicals and fuels due to the readily available fermentable sugars that can be extracted from the juice, and the additional stream of fermentable sugars that can be obtained from the cell wall polysaccharides in the bagasse. An important selection criterion for new sweet sorghum germplasm is resistance to anthracnose, a disease caused by the fungal pathogen Colletotrichum sublineolum. The identification of novel anthracnose-resistance sources present in sweet sorghum germplasm offers a fast track towards the development of new resistant sweet sorghum germplasm. We established a sweet sorghum diversity panel (SWDP) of 272 accessions from the USDA-ARS National Plant Germplasm (NPGS) collection that includes landraces from 22 countries and advanced breeding material, and that represents ~15% of the NPGS sweet sorghum collection. Genomic characterization of the SWDP identified 171,954 single nucleotide polymorphisms (SNPs) with an average of one SNP per 4,071 kb. Population structure analysis revealed that the SWDP could be stratified into four populations and one admixed group, and that this population structure could be aligned to sorghum's racial classification. Results from a two-year replicated trial of the SWDP for anthracnose resistance response in Texas, Georgia, Florida, and Puerto Rico showed 27 accessions to be resistant across locations, while 145 accessions showed variable resistance response against local pathotypes. A genome-wide association study identified 16 novel genomic regions associated with anthracnose resistance. Four resistance loci on chromosomes 3, 6, 8 and 9 were identified against pathotypes from Puerto Rico, and two resistance loci on chromosomes 3 and 8 against pathotypes from Texas. In Georgia and Florida, three resistance loci were detected on chromosomes 4, 5, 6 and four on chromosomes 4, 5 (two loci) and 7, respectively. One resistance locus on chromosome 2 was effective against pathotypes from Texas and Puerto Rico and a genomic region of 41.6 kb at the tip of chromosome 8 was associated with resistance response observed in Georgia, Texas, and Puerto Rico. This publicly available SWDP and the extensive evaluation of anthracnose resistance represent a valuable genomic resource for the improvement of sorghum.

Discovering useful genetic variation in the seed parent gene pool for sorghum improvement.

Multi-parent populations contain valuable genetic material for dissecting complex, quantitative traits and provide a unique opportunity to capture multi-allelic variation compared to the biparental populations. A multi-parent advanced generation inter-cross (MAGIC) B-line (MBL) population composed of 708 F6 recombinant inbred lines (RILs), was recently developed from four diverse founders. These selected founders strategically represented the four most prevalent botanical races (kafir, guinea, durra, and caudatum) to capture a significant source of genetic variation to study the quantitative traits in grain sorghum [Sorghum bicolor (L.) Moench]. MBL was phenotyped at two field locations for seven yield-influencing traits: panicle type (PT), days to anthesis (DTA), plant height (PH), grain yield (GY), 1000-grain weight (TGW), tiller number per meter (TN) and yield per panicle (YPP). High phenotypic variation was observed for all the quantitative traits, with broad-sense heritabilities ranging from 0.34 (TN) to 0.84 (PH). The entire population was genotyped using Diversity Arrays Technology (DArTseq), and 8,800 single nucleotide polymorphisms (SNPs) were generated. A set of polymorphic, quality-filtered markers (3,751 SNPs) and phenotypic data were used for genome-wide association studies (GWAS). We identified 52 marker-trait associations (MTAs) for the seven traits using BLUPs generated from replicated plots in two locations. We also identified desirable allelic combinations based on the plant height loci (Dw1, Dw2, and Dw3), which influences yield related traits. Additionally, two novel MTAs were identified each on Chr1 and Chr7 for yield traits independent of dwarfing genes. We further performed a multi-variate adaptive shrinkage analysis and 15 MTAs with pleiotropic effect were identified. The five best performing MBL progenies were selected carrying desirable allelic combinations. Since the MBL population was designed to capture significant diversity for maintainer line (B-line) accessions, these progenies can serve as valuable resources to develop superior sorghum hybrids after validation of their general combining abilities via crossing with elite pollinators. Further, newly identified desirable allelic combinations can be used to enrich the maintainer germplasm lines through marker-assisted backcross breeding.

Impact of in‐season split application of nitrogen on intra‐panicle grain dynamics, grain quality, and vegetative indices that govern nitrogen use efficiency in sorghum

AbstractBackgroundThe correct rate and timing of nitrogen (N) has the potential to improve sorghum productivity through modified grain yield components and quality. The impacts of in‐season split application of N have little documentation.AimAn experiment was conducted to determine the optimum rate and timing of N to relate vegetative indices that govern nitrogen use efficiency and to maximize grain yield and quality under different soil types.MethodsPioneer 86P20 was grown in three environments on two different soil types following a completely randomized block design with nine N application treatments. Treatments included differing N rates applied at critical developmental stages of sorghum (planting, panicle initiation, and booting), accompanied with high temporal aerial phenotyping.ResultsOpportunities to increase grain protein content while using split N applications were observed, with panicle initiation identified as a critical developmental stage. In‐season split application of N enhances grain yield under low soil mineral N. Split application of 31 kg N ha−1 each at the time of planting, panicle initiation, and booting emerged as optimum N treatment to increase protein content in sorghum. Vegetative indices, that is, normalized difference vegetation index and normalized difference red edge index are capable of predicting grain yield and protein content, respectively. Intra‐panicle grain numbers and weights were altered significantly at different portions within panicles, with an opportunity to enhance yield potential at the bottom portion. The strong stay‐green trait in this hybrid locked a large proportion of nitrogen in the leaves, which warrants the need for balancing stay‐green and senescence in sorghum improvement programs.ConclusionsFindings highlight that in grain sorghum remobilization of residual leaf N into grain is a target to increase yield and grain quality. An optimized stay‐green trait balanced with senescence is recommended for enhancing sorghum yield potential.

Inventory of on-farm sorghum landrace diversity and climate adaptation in Tigray, Northern Ethiopia: implications for sorghum breeding and conservation

The study was conducted with the aim of inventorying and assessing the level of sorghum landraces richness, estimating the extent and patterns of phenotypic diversity, identifying race type, and predicting suitable areas of production using future climate scenarios in Tigray, Northern Ethiopia. Overall, 358 landraces from 125 independent farmers’ fields in 20 districts belonging to four zones of Tigray were surveyed. Landraces richness, frequency of character states, and diversity levels were estimated via Margalef’s, Menhinick’s and Shannon–Weaver (H′) indices for each zone and altitude classes. Suitable areas for sorghum cultivation in the future were predicted using DIVA-GIS. Altogether, 140 distinctly named landraces were identified and collected. Southern zone has the highest richness (DMg = 10.74, DMn = 5.0) followed by central (DMg = 8.54, DMn = 3.80). The estimated H′ for the phenotypic character states ranged from 0.24 (seed form) to 0.95 (rachis branch length). Highest diversity estimate was found in northwest (H′ = 0.71) followed by central zone (H′ = 0.64). Respectively, H′ was 0.70, 0.68, and 0.61 in lowland, intermediate, and highland elevations. In general, lowlands of northwest, central, and southern zones are identified as potential sites for germplasm conservation and utilization. The races durra, bicolor, caudatum, and durra-bicolor were found with durra as the dominant race (79%). All the currently surveyed areas and many other sites in Tigray are predicted to be suitable for future sorghum production under the changing climate scenario. Copies of all the 358 sorghum landraces are deposited in the national gene bank for use in future sorghum breeding work. The wealth of sorghum landraces diversity could be used in sorghum improvement programs.

Biochemical and Morphological Assessment of Rabi Sorghum Genotypes for Shootfly Resistance

The present investigation was conducted at Sorghum Improvement Project and Department of Biochemistry, Mahatma Phule Krishi Vidyapeeth, Rahuri, Maharashtra, India during rabi 2019–20 for assessment of rabi sorghum genotypes for shootfly through biochemical perspective. Sorghum is an important food and fodder crop of dry land agriculture. The experimental material consisted of 11 sorghum genotypes viz; RSV 1628, RSV 1023, RSV 1910, RSV 2371, RSV 1945, RSV 1838, RSV 2025, RSV 1918, RSV 1988, RSV 2391, RSV 1941, three varieties viz., Phule Vasudha, Phule Revati, M-35-1, three shootfly resistant checks viz., RSV 1188, IS 18551, RSE 3 and a susceptible check i.e. DJ 6514. The experiments were conducted under pot culture and field conditions at different stages. Resistance against shootfly in sorghum was governed by the physical and chemical genes. The morphological characters like trichome density, oviposition and dead heart percentage and biochemical attributes like polyphenol oxidase, peroxidise and chlorophyll content can be used as marker traits in shootfly resistance breeding programme to broaden the genetic base and increase the levels of resistance to sorghum. The sorghum genotype RSE 3, RSV 1945, RSV 1941, RSV 1188, and RSV 2371 recorded higher polyphenol oxidase activity at 28 DAE as compared to other genotypes. So, these sorghum genotypes are good source for shootfly resistance breeding. The genotype RSE 03, RSV 1941 and RSV 1188 exhibited positive results for shootfly resistance and can be used as donor for shootfly breeding programme.

Effect of nitrogen fertilizer on nitrogen use efficiency and yield of selected sorghum genotypes in semi-arid regions of Kenya

Sorghum production in semi-arid lands is constrained by inadequate soil moisture and low nitrogen. Research was carried out between 2018-2020 to determine the effect of nitrogen fertilizer on nitrogen use efficiency, yield on selected sorghum genotypes and genotypes suitable for low soil fertility in semi-arid lands. The experiment was a randomized complete block design in a split-plot arrangement with 11 sorghum genotypes in the main plot and nitrogen (0, 6.5 and 32.5 kgha-1) as the sub-plots in three replicates. Nitrogen use efficiency (NUE) and its indices agronomic efficiency (AE), nitrogen internal utilization (IE), physiological efficiency (PE), nitrogen recovery efficiency, nitrogen harvest index (NHI) and partial factor productivity (PFP) were obtained from sorghum yield data and nitrogen uptake. The results showed that nitrogen application at 6.5 kgha-1 and 32.5 kgha-1 significantly increased grain yield, stover weight and total dry matter (TDM) by 43% and 116%, 39% and 85% and 42% and 57% respectively. Sorghum genotypes TTKKIAMA6, KTIRASTAMMA4, SNYAKTOSA5, and MKNKKIRWMA2 had significantly higher grain yield and low N uptake implying they are N-efficient. NUE of sorghum decreased with increasing N application. Nitrogen internal utilization efficiency (IE) was significantly higher at zero N application rate implying better N assimilation by sorghum genotypes at low N. AE, PE, RE and PFP were all significantly higher at 6.5 kg N ha-1. All tested genotypes had significantly high NUE (90 to 1148 kgkg-1, RE (27 to 94 kgkg-1), AE (41 to 139 kgkg-1), PE (27 to 84 kgkg-1) and IE (41 to 139 kgkg-1) than the check (Gadam). It was concluded that sorghum genotypes yield parameters were increased by nitrogen application, NUE was highest at low N levels and its indices were significantly higher at 6.5 kg Nha-1. Four genotypes were found to be highly N-efficient and are recommended for sorghum improvement.

Inbred phenotypic data and non‐additive effects can enhance genomic prediction models for hybrid grain sorghum

AbstractImplementation of genomic prediction can bolster rates of genetic gain in sorghum improvement and permit more efficient allocation of resources within hybrid breeding programs. In the present study, alternative genomic prediction models were compared to assess the potential benefits of including inbred phenotypic records, dominance effects, and genotype‐by‐environment (G×E) interactions in predicting hybrid grain sorghum performance. Comparisons were made in a set of 395 hybrid combinations derived from 92 parental inbred lines tested in a sparse multi‐environment trial. Phenotypic data were collected on hybrids and inbreds for days to mid‐anthesis, grain yield, and plant height, and genomic data on parental inbreds were collected by genotyping × sequencing. A significant increase in prediction accuracy was observed when modeling G×E effects; however, dominance effects did not contribute to the overall predictive ability of models in this data set. Including phenotypic data from parental lines significantly improved the prediction of hybrid merit by as much as 17% for days to mid‐anthesis, 14% for grain yield, and 33% for plant height when there were no testcross records for a given parental line. Alternatively, similar improvements were not as consistent when the training set included lines already tested in hybrid combinations. Thus, hybrid crop breeders can further optimize genomic predictions for un‐testcrossed lines by including non‐additive effects and inbred data.

Genetic diversity, importance and prospects for varietal improvement of sweet grain sorghum in Burkina Faso

Sweet grain sorghum is a very important cereal for urban and especially rural communities in Burkina Faso. It is mainly grown by traditional farmers. Consumed fresh in a pasty state, the grains have a huge nutritional potential and could improve the quality of the consumers' diet. In addition, the marketing of panicles harvested at the doughy grain stage offers substantial income benefits to farmers and traders. The straw of this sorghum is also an excellent fodder for the integration of agriculture with breeding. Despite the many advantages of this crop, it has long remained under-exploited due to insufficient knowledge of its potential and little research attention. However, the conservation and improvement of the quality of sweet grain sorghum is an important issue for the various stakeholders in the crop chain. Thus, based on the various research studies conducted on the crop since 2008 in Burkina Faso, this literature review highlights the importance of sweet grain sorghum, its role in crop diversification, its nutritional properties, as well as the future possibilities for selection and genetic improvement of this species.

Genetic diversity and population structure of sorghum [Sorghum bicolor (L.) Moench] genotypes in Ethiopia as revealed by microsatellite markers

In the tropical and semi-arid regions of Africa, sorghum [Sorghum bicolor (L.) Moench] is mainly grown as a major food security crop. Understanding the extent and pattern of genetic variability is a prerequisite criterion for sorghum improvement and conservation. The genetic diversity and population structure of 100 genotypes of sorghum were profiled using 15 microsatellite loci. A total of 108 alleles, with an overall mean of 7.2 alleles per locus, were produced by all of the microsatellite loci used due to their high polymorphism. Polymorphic information content values ranging from 0.68 to 0.89 indicated that all of the loci are effective genetic tools for analysing the genetic structure of sorghum. Different diversity metrics were used to evaluate genetic diversity among populations, and Nei's gene diversity index ranged from 0.74 to 0.81 with an overall mean of 0.78. Poor genetic differentiation (FST: 0.02; p < 0.0001) was found, where 98% of entire variability was accounted by the within populations genetic variability, leaving only 2.32% among populations. The highest genetic differentiation and Nis's genetic distance were observed between the sorghum populations of the Southern Nation and Nationalities Peoples and Dire Dawa regions. Due to increased gene flow (Nm = 10.53), the clustering, principal coordinate analysis and STRUCTURE analysis failed to categorize the populations into genetically different groups corresponding to their geographic sampling areas. In general, it was found that the microsatellite loci were highly informative and therefore valuable genetic tools to unfold the genetic diversity and population structure of Ethiopian sorghum genotypes. Among the five populations studied, sorghum populations from Amhara and Oromia had the highest genetic variation, indicating that the regions could be perhaps hotspots for useful alleles for the development of better-performing genotypes, and also for designing appropriate germplasm management strategies.

India's rainfed sorghum improvement: Three decades of genetic gain assessment for yield, grain quality, grain mold and shoot fly resistance.

Sorghum is a climate-resilient cereal and staple food crop for more than 200 million people in arid and semi-arid countries of Asia and Africa. Despite the economic importance, the productivity of sorghum in India is constrained by biotic and abiotic stresses such as incidences of shoot fly, grain mold and drought. Indian sorghum breeding focused on dual-purpose (grain and fodder), short-duration varieties with multiple resistance/tolerance to pests and diseases and improved nutritional quality (high protein, iron and zinc and low fat). In this context, it is important to ascertain the genetic progress made over 30 years by assessing the efficiency of past achievements in genetic yield potential and to facilitate future genetic improvement. The current study determined the genetic gain in 24 sorghum varieties developed by the national and state level research systems during 1990-2020. The 24 varieties were evaluated for three years (2018-2020) at six locations in Telangana state for yield, nutritional characteristics and tolerance to shoot fly and grain mold. The absolute grain yield genetic gain from the base year 1990 is 44.93 kg/ha/yr over the first released variety CSV 15. The realized mean yield increased from 2658 kg/ha of the variety CSV 15 in 1990s to 4069 kg/ha of SPV 2579 developed in 2020s. The absolute genetic gain for grain mold resistance is -0.11 per year with an overall relative gain of 1.46% over CSV 15. The top varieties for grain yield (SPV 2579, SPV 2678 and SPV 2578), fodder yield (PYPS 2, SPV 2769 and SPV 2679), shoot fly tolerance (PYPS 8, PYPS 2 and SPV 2179), mold tolerance (PYPS 8, PYPS 2 and SPV 2579) and high protein (PYPS 8, PYPS 2 and SPV 2769) were identified for possible scale up and further use in breeding program diversification. The study revealed that sorghum varieties bred with diverse genetic backgrounds such as landraces and with tolerance to pests and diseases had stable yield performance. Application of genomics and other precision tools can double genetic gains for these traits to strengthen sorghum cultivation in rainfed areas serving food and nutrition security.

Heterosis Studies for Grain Yield and Yield Components in Rabi Sorghum [Sorghum bicolor (L.) Moench.

The present investigation was conducted to assess the magnitude of heterosis of rabi sorghum (Sorghum bicolor (L.) Moench) developed by crossing four lines and twelve testers (in a line × tester design) to produce 48 F1 cross combinations at the Sorghum Improvement Project, MPKV., Rahuri, Maharashtra. To identify the high-yielding Rabi sorghum hybrids, promising hybrids were sorted out based on positive significant standard heterosis for grain yield per plant. A total of twenty-one hybrids exhibited significant standard heterosis for grain yield per plant. The best cross combination was 104A x RSR 1012 (86.59%) for maximum standard heterosis, followed by the cross 104A X RSR 1019 (73.17%) and 104 A X RSR 1003 (70.73%) for grain yield per plant. Heterosis has been considered a well-proven method for increasing yield and improving traits in crops, and the exploitation of heterosis for the hybrid development programme is considered one of the greatest breakthroughs in plant breeding.

PERFORMANCE AND TRANSCRIPTOMIC ANALYSIS OF SORGHUM BICOLOR RESPONDING TO DROUGHT STRESS

Drought is a severe causal factor of reduced crop yields than other abiotic stresses. Therefore, four sorghum genotypes underwent evaluation for their drought tolerance under three irrigation levels (100%, 70%, and 40% from evapotranspiration) under three sowing dates at the Higher Institute for Agricultural Cooperation Farm, Regwa region, Alexandria Desert Road, Egypt, to study the mean performance of grain yield plant-1 and transcriptomic analysis. The performance results reported that Shandaweel-6 and Hybrid-306 revealed the highest drought-tolerant hybrids, while Dorado and Giza-113 cultivars showed the lowest. The transcriptomic profiling of sorghum under normal and drought stress used the RNA-Seq method. Two differentially-expressed genes (DEGs) in leaves respond to drought. In the DREB2 case, the greatest average fold change showed 10.7 and 9.3 for the tolerant hybrids, Hybrid-306 and Shandaweel-6, respectively. Both genotypes performed significantly higher than the average fold change calculated for the sensitive genotypes Dorado and Giza-113 cultivars. This study contributes to a better understanding of the molecular basis of drought tolerance of sorghum and promotes sorghum improvement.

BREEDING SORGHUM FOR GRAIN, FORAGE AND BIOENERGY IN BRAZIL

Sorghum is a versatile crop used for energy production, human and animal feedings, and raw material for industry. The grain sorghum is the fifth most important cereal worldwide, and Brazil is one of the top 10 sorghum producers. In the last 40 years, the sorghum grain yield in Brazil has increased to 32.70 kg ha-1 year -1. Although this clear evolution, much remains to be done, and sorghum breeders in Brazil still face several challenges. This review discusses the main characteristics of sorghum genetics and breeding, aiming for sorghum improvement for food, fodder, feed, and fuel uses. Herein will be highlighted essential topics related to the genetic control of the main interest traits; conventional sorghum breeding; the development of sorghum lines and hybrids; the use of male-sterility in sorghum breeding; the implication of genotypes-by-environments interaction in sorghum, the use of genome-wide association studies, and genomic prediction to maximize the efficiency of the sorghum breeding programs.

Genome-wide analyses using multi-locus models revealed marker-trait associations for major agronomic traits in Sorghum bicolor.

Globally, sorghum is the fifth most important cereal crop, and it is a major crop in Ethiopia, where it has a high genetic diversity. The country’s sorghum gene pool contributes significantly to sorghum improvement worldwide. This study aimed to identify genomic regions and candidate genes associated with major agronomic traits in sorghum by using its genetic resources in Ethiopia for a genome-wide association study (GWAS). Phenotypic data of days to flowering (DTF), plant height (PH), panicle length (PALH), panicle width (PAWD), panicle weight (PAWT), and grain yield (GY) were collected from a GWAS panel comprising 324 sorghum accessions grown in three environments. SeqSNP, a targeted genotyping method, was used to genotype the panel using 5,000 gene-based single nucleotide polymorphism (SNP) markers. For marker-trait association (MTA) analyses, fixed and random model circulating probability unification (FarmCPU), and Bayesian-information and linkage-disequilibrium iteratively nested keyway (BLINK) models were used. In all traits, high phenotypic variation was observed, with broad-sense heritability ranging from 0.32 (for GY) to 0.90 (for PALH). A population structure, principal component analysis, and kinship analysis revealed that the accessions could be divided into two groups. In total, 54 MTAs were identified, 11 of which were detected by both BLINK and farmCPU. MTAs identified for each trait ranged from five (PAWT and GY) to fourteen (PH) representing both novel and previously identified quantitative trait loci (QTLs). Three SNPs were associated with more than one trait, including a SNP within the Sobic.004G189200 gene that was associated with PH and PAWT. Major effect SNP loci, Sbi2393610 (PVE = 23.3%), Sbi10438246 (PVE = 35.2%), Sbi17789352 (PVE = 11.9%) and Sbi30169733 (PVE = 18.9%) on chromosomes 1, 3, 5 and 9 that showed strong association signals for PAWD, DTF, GY and PALH, respectively, were major findings of this study. The SNP markers and candidate genes identified in this study provide insights into the genetic control of grain yield and related agronomic traits, and once validated, the markers could be used in genomics-led breeding.