Maize Genomics and Genetics 2024, Vol.15, No.3, 111-122 http://cropscipublisher.com/index.php/mgg 115 4 Applications and Case Studies 4.1 Drought and heat tolerance Drought and heat stress are significant challenges in maize production, particularly in tropical and subtropical regions. Genomics-assisted breeding has been pivotal in developing drought-tolerant maize varieties. Techniques such as rapid DNA and RNA sequencing, high-throughput SNP genotyping, and genomic selection have accelerated the breeding cycle and improved the genetic gain under stress conditions (Nepolean et al., 2018; Yuan et al., 2019; Liu and Qin, 2021) (Figure 2). For instance, a study involving genome-wide association mapping and genomic prediction analyses identified key genomic regions associated with grain yield and flowering time under drought stress, providing valuable insights for breeding stress-tolerant maize germplasm. Additionally, QTL analysis across multiple environments has revealed promising chromosome regions associated with yield-related traits under drought conditions, supporting marker-assisted breeding efforts. Figure 2 The results of gene ontology (GO)-based functional enrichment analysis (A) and the expression profiling analysis (B) (Adopted from Yuan et al., 2019) Image caption: The GO terms in brown, yellow, and green colored boxes are cellular component, molecular function, and biological process categories, respectively. AC7643 and RIL208 are drought tolerance maize inbred lines, AC7729/TZSRW and RIL64 are drought sensitive maize inbred lines, and RIL 208 and RIL64 are derived from the cross of AC7643 and AC7729/TZSRW (Adopted from Yuan et al., 2019) Yuan et al. (2019) focuses on identifying and analyzing candidate genes in maize that contribute to drought stress tolerance. Through gene ontology (GO) functional enrichment analysis, it highlights significant enrichment of genes involved in metabolic processes, cellular components, and transcription regulation. The expression profiling under drought conditions revealed 46 differentially expressed genes (DEGs) with notable changes in expression levels, correlating with drought tolerance across different maize lines. These findings emphasize the crucial role of specific genes, particularly transcription factors, in responding to drought stress. The research provides essential insights into the genetic basis of drought tolerance, which can inform breeding programs aimed at enhancing crop resilience. 4.2 Disease resistance Genomics-assisted breeding has also been instrumental in enhancing disease resistance in maize. By leveraging genomic data, researchers can accelerate the resistance breeding process through family or population mapping and genomic selection (Miedaner et al., 2020). For example, significant progress has been made in breeding maize resistant to diseases such as Gibberella ear rot, Fusarium ear rot, and Northern corn leaf blight. These diseases are controlled by numerous QTL scattered across the genome, often located in hotspots (Miedaner et al., 2020).
RkJQdWJsaXNoZXIy MjQ4ODYzNQ==