Plant Gene and Trait 2024, Vol.15, No.6, 295-304 http://genbreedpublisher.com/index.php/pgt 296 and genomic characteristics of current sorghum germplasm, highlighting key findings and advancements, discussing the methods and technologies used in sorghum germplasm evaluation-including phenotyping platforms, genome sequencing, and genome-wide association studies (GWAS) and examining the practical applications of these resources in plant breeding and crop improvement, particularly in developing sorghum varieties with resistance and high yield, aiming to guide future research and breeding efforts to fully utilize the potential of sorghum germplasm resources. 2 Current Status of sorghum germplasm Collection 2.1 Current status of germplasm collections in the world and major sorghum growing regions Sorghum germplasm collections are extensive and globally distributed, with significant repositories in various regions. The International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) maintains a substantial collection exceeding 37 000 accessions, from which a core collection and a mini core collection have been developed to facilitate research and utilization (Upadhyaya et al., 2009). Similarly, the USDA National Plant germplasm System (NPGS) holds the largest sorghum germplasm collection worldwide, including 7 217 accessions from Ethiopia, a key center of sorghum diversity (Cuevas et al., 2016). These collections are crucial for preserving genetic diversity and supporting breeding programs aimed at improving sorghum's agronomic traits and stress resistance. 2.2 Important sources of sorghum germplasm Sorghum germplasm sources are diverse, encompassing both wild and cultivated species. The genus sorghum includes 24 species, with cultivated sorghum (sorghum bicolor) derived from the wild progenitor S. bicolor subsp. verticilliflorum, predominantly found in Africa (Ananda et al., 2020). Wild sorghum species, particularly those native to Australia and Africa, are valuable for their genetic traits, such as drought tolerance and disease resistance, which are crucial for crop improvement. The Ethiopian sorghum germplasm, characterized by high genetic and phenotypic diversity, represents a significant source of adaptive traits and rare alleles (Girma et al., 2020). Additionally, germplasm from West and Central Africa, including Senegal and Burkina Faso, has been identified as a rich source of resistance genes to fungal diseases like anthracnose and grain mold (Cuevas et al., 2016; Cuevas et al., 2018). 2.3 Current collection challenges and potential solutions The collection and utilization of sorghum germplasm face several challenges. One major issue is the underrepresentation of wild species in germplasm collections, which limits the genetic diversity available for breeding programs (Ananda et al., 2020). Additionally, the large size of some collections, such as the ICRISAT's core collection, can be cumbersome for researchers to manage and utilize effectively. To address these challenges, the development of mini core collections, which represent a smaller, more manageable subset of the larger collections, has been proposed and implemented successfully. Furthermore, extensive genomic characterization and phenotyping of germplasm, as demonstrated in the Ethiopian and Senegalese collections, can enhance the identification and utilization of valuable genetic traits (Cuevas et al., 2018). These efforts, combined with targeted conservation strategies and international collaboration, can improve the efficiency and effectiveness of sorghum germplasm collection and utilization. 3 Phenotypic and Genotypic Evaluation of Sorghum Germplasm Resources 3.1 Evaluation methods for phenotypic diversity of germplasm resources Phenotypic evaluation of sorghum germplasm resources involves assessing various traits such as morphology, stress resistance, and yield. For instance, the Ethiopian sorghum germplasm was phenotyped for different traits across multiple locations, revealing significant genetic diversity and rare natural variations (Girma et al., 2020). Similarly, the ICRISAT gene bank developed a mini core collection of sorghum, which was evaluated for 11 qualitative and 10 quantitative traits, including resistance to biotic and abiotic stresses (Upadhyaya et al., 2009). These evaluations often use hierarchical cluster analysis and other statistical methods to identify phenotypic diversity and correlations among traits (Enyew et al., 2021).
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