Molecular Entomology 2024, Vol.15, No.1, 32-42 http://emtoscipublisher.com/index.php/me 33 marker-assisted selection. Evaluate the effectiveness of resistant varieties is assessing the performance of newly developed resistant rice lines in terms of pest resistance and agronomic traits. By synthesizing findings from recent research, this study aims to highlight the progress made in breeding insect-resistant rice and identify future directions for enhancing resistance through genetic and breeding innovations. 1 Genetic Foundations of Resistance in Rice 1.1 Resistance to various insect pests in rice Genetic traits that confer resistance to various insect pests in rice are diverse and have been identified through extensive research. For instance, the novel resistance gene Bph, derived from the wild rice species Oryza rufipogon Griff., has been shown to provide high resistance to both brown planthopper (BPH) and white-backed planthopper (WBPH) (Figure 1) (Yang et al., 2020). Similarly, the gene Bph (Radchenko et al., 2022), identified through genome-wide association studies, confers resistance to multiple BPH biotypes and is associated with high nucleotide diversity, indicating its evolutionary significance (Zhou et al., 2021). Additionally, the deficiency of the mitochondrial outer membrane protein 64 (OM64) gene in rice has been linked to increased resistance to both piercing-sucking insects like BPH and chewing insects such as the striped stem borer (SSB) (Guo et al., 2020). The findings of Zhou et al., (2021) indicate significant variations in plant responses and pest infestation levels. The visual data demonstrate differences in plant health and growth under varying conditions, as well as the distribution of certain traits or measurements among different groups. Statistical analyses highlight distinct patterns and significant differences among the biotypes studied, reflecting variations in resistance and susceptibility. This comprehensive visual representation underscores the complexity of plant-pest interactions and the importance of understanding biotype-specific responses for effective management strategies. 1.2 Molecular genetics The molecular genetics underlying resistance in rice involves various genes and their interactions with pest populations. For example, many insect resistance genes have been identified, and 14 such genes have been cloned via a map-based cloning approach. These genes activate defense pathways, including the expression of defense-related genes such as mitogen-activated protein kinase, plant hormone, and transcription factors (Du et al., 2020). The Bph14 and OsLecRK1 genes, when stacked together, have been shown to provide resistance to BPH, demonstrating the potential of combining multiple resistance genes for enhanced protection. Furthermore, the molecular mechanisms of BPH resistance involve the deposition of callose and cell wall thickening, which inhibit BPH feeding and damage. 1.3 Breeding Strategies Breeding strategies for incorporating resistance traits into rice varieties have evolved significantly, encompassing both traditional and modern techniques. Traditional breeding approaches have successfully incorporated resistance to insect pests through the selection and crossing of resistant varieties. However, the continuous evolution of virulent pest biotypes necessitates the use of advanced molecular approaches. Marker-assisted selection (MAS) and transgene stacking systems have been employed to combine multiple resistance genes from diverse sources into a single genetic background, resulting in rice varieties with durable resistance (Li et al., 2020). Additionally, the identification of quantitative trait loci (QTLs) such as BPH41 and BPH42 has facilitated the development of BPH-resistant rice varieties through fine mapping and the use of recombinant lines (Tan et al., 2021). In summary, the genetic foundations of resistance in rice involve a complex interplay of genetic traits, molecular mechanisms, and innovative breeding strategies. The integration of traditional and modern approaches has led to the development of rice varieties with enhanced resistance to various insect pests, contributing to sustainable rice production and pest management.
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