Plant Gene and Trait 2024, Vol.15, No.6, 285-294 http://genbreedpublisher.com/index.php/pgt 290 2022). The development of sex-specific molecular markers, such as the AFLP and SCAR markers identified in recent studies, provides a reliable and early method for sex determination, which is essential for the strategic planning of breeding programs (Wang et al., 2011; Wang et al., 2020). 5.2 Methodology for applying markers in breeding programs The application of sex-specific markers in breeding programs involves several key steps. Initially, molecular markers such as AFLP and ddRAD markers are identified through comprehensive screening and bioinformatics analysis. For instance, the AFLP marker E-ACA/M-CTT and the ddRAD marker MSL4 have been successfully developed for E. ulmoides (Wang et al., 2011; Wang et al., 2020). These markers are then validated through PCR amplification and sequencing to ensure their reliability and reproducibility. Once validated, these markers can be used to screen seedlings at an early stage, allowing breeders to select the desired sex for further cultivation and breeding. This process not only accelerates the breeding cycle but also enhances the precision of breeding programs by ensuring the correct sex ratio in breeding populations. 5.3 Analysis of a case study: benefits and challenges The integration of sex-specific markers in the breeding program of E. ulmoides has demonstrated several benefits. The primary advantage is the ability to identify the sex of plants at the seedling stage, which significantly reduces the time and resources required for breeding. For example, the SCAR marker developed from the AFLP marker allows for early sexual identification, facilitating more efficient breeding programs (Wang et al., 2011). Similarly, the ddRAD marker MSL4 provides a consistent and reproducible method for sex determination, which is valuable for rapid breeding and commercial production (Wang et al., 2020; Ohbayashi, 2021). However, challenges remain, such as the need for extensive initial screening and validation of markers, as well as the potential for genetic variability that may affect marker reliability. Addressing these challenges requires ongoing research and refinement of marker-assisted techniques. 5.4 Future directions for marker-assisted selection Future directions for marker-assisted selection in E. ulmoides breeding programs include the development of more comprehensive marker panels that can identify both male and female plants with high accuracy. Additionally, integrating these markers with other genomic tools and technologies, such as genome-wide association studies (GWAS) and CRISPR-based gene editing, could further enhance the precision and efficiency of breeding programs. Continued research into the genetic basis of sex determination in E. ulmoides will also be crucial for developing more robust and versatile markers. Ultimately, the goal is to create a streamlined and effective breeding process that maximizes the economic and ecological benefits of E. ulmoides cultivation (Jin et al., 2020). 6 Key Findings in Marker Polymorphism and Their Implications 6.1 Analysis of marker polymorphism and sex segregation In the study of Eucommia ulmoides, several types of markers were analyzed for their polymorphism and ability to segregate by sex. The use of Amplified Fragment Length Polymorphism (AFLP) markers revealed a 350 bp male-specific marker, which was subsequently converted into a 247 bp Sequence Characterized Amplified Region (SCAR) marker. This SCAR marker demonstrated a clear ability to distinguish male plants from female ones, facilitating early sex identification (Wang et al., 2011). Additionally, Random Amplified Polymorphic DNA (RAPD) markers identified a 569 bp marker exclusive to pistillate (female) plants, which was also converted into a SCAR marker for practical use in sex determination (Xu et al., 2004). 6.2 Efficacy of developed markers The developed markers showed high efficacy in identifying the sex of Eucommia ulmoides plants. The 247 bp SCAR marker derived from the AFLP marker was effective in early sexual identification, which is crucial for breeding programs that aim to optimize the economic value of the species (Wang et al., 2011). Similarly, the 569 bp SCAR marker derived from the RAPD marker was confirmed to be exclusive to pistillate plants, ensuring reliable sex determination even before the plants reach reproductive maturity (Xu et al., 2004).
RkJQdWJsaXNoZXIy MjQ4ODYzMg==