Plant Gene and Trait 2024, Vol.15, No.5, 230-242 http://genbreedpublisher.com/index.php/pgt 237 Figure 3 Grain length and width of the eight founders and JAM lines (Adopted from Ogawa et al., 2018) Image caption: (A) Alignments of 50 grains of each of the four japonica cultivars (Akidawara [AK], Bekogonomi [BE], Tachiaoba [TC], and Mizuhochikara [MI]) and four indica cultivars (Suweon 258 [SU], Takanari [TK], Hokuriku 193 [HO], and Ruriaoba [RU]) used as founders. Pictures of the grain of each founder were taken individually and then merged. (B) Violin plots of the grain length and width of the founders. They include information on kernel density estimation, quantiles (black boxes), and median values (white circles). Different letters indicate significant differences (Tukey method, P < 0.05). (C) Alignments of 50 grains each of four JAM lines showing characteristic features. (D) Scatter plot of average grain length and width for each JAM line and the eight founders. White bars indicate 1 cm (Adopted from Ogawa et al., 2018) 8 Implications for Rice Breeding and Cultivar Development 8.1 Utilizing genetic information in breeding programs The identification of numerous QTLs and candidate genes associated with rice grain shape and palatability provides a valuable resource for rice breeding programs. The findings of Huang et al. (2013) identify the protein products of 13 genes and the chromosomal locations of 15 fine-mapped QTLs, highlighting the complex potential of genetic information in breeding programs. GWAS have further identified significant QTLs and candidate genes, such as GS3, GW5, and OsDER1, which can be utilized to enhance grain shape and quality (Meng et al., 2022). Additionally, the identification of novel QTLs and candidate genes, such as qGL-7a, qGL-8, and qGL-11a, provides new targets for genetic improvement (Kang et al., 2021). The combination of these genetic insights into breeding strategies not only accelerates the development of rice cultivars with desirable traits but also enables the fine-tuning of specific attributes like grain length, width, and texture. By applying molecular tools such as MAS and GS, breeders can efficiently target these QTLs to produce rice varieties with improved yield, grain shape, and palatability, meeting both agronomic and consumer demands. 8.2 Challenges in breeding for grain shape and palatability Despite significant advancements in identifying genetic determinants of grain shape and palatability, several challenges remain in breeding programs. One major challenge is the functional characterization of identified genes at the biochemical level, which is essential for understanding their roles in grain development and quality (Huang et al., 2013). While genomic studies have identified numerous genes associated with these traits, translating this information into practical breeding applications requires detailed functional insights. Additionally, the complex genetic architecture of traits such as grain shape and palatability, which are influenced by multiple genes and environmental factors, complicates the breeding process (Wang et al., 2023). The need for high-resolution mapping and validation of QTLs in diverse genetic backgrounds further adds to the complexity (Shang et al., 2020). Moreover, the trade-offs between different agronomic traits, such as yield and quality, present a significant
RkJQdWJsaXNoZXIy MjQ4ODYzMg==