Triticeae Genomics and Genetics, 2025, Vol.16, No.6, 254-261 http://cropscipublisher.com/index.php/tgg 255 2 Biological Basis of Lodging Resistance in Rye 2.1 Types of lodging and influencing factors (stem strength, root development, plant height) The most common types of rye lodging in the field can actually be divided into two categories: some have broken stems, and some have loose root systems that cause the entire plant to lean over. Both situations will affect the output, but the factors causing lodging are not exactly the same. For instance, whether the stem can hold up mainly depends on the anatomical structure - whether the number of vascular bundles is sufficient, whether the thick-walled tissue is well-developed, and whether the cell wall is thick enough. The root lodging is more related to whether the root system is deeply rooted and how strong its ability to grip the ground is. Plant height is often regarded as a risk indicator. Tall plants are indeed prone to toppling, but this is not absolute. Some rye varieties, although not short, have a higher content of lignin, cellulose, and hemicellulose in their stems and a harder structure, and thus are less likely to toppling (Niu et al., 2022). 2.2 Morphological and physiological indicators related to lodging resistance Morphologically speaking, the length of the stem, the weight of the internodes and the wall thickness are often closely related to lodging, but the three do not change in the same direction. If the internodes are too heavy or the stems are too long, the risk of lodging will increase instead. A thicker stem wall can significantly enhance stability. Physiologically, wheat with a high density of vascular bundles and sufficient overall biomass is generally more robust. In addition to the deposition of lignin or silicon, after the hardness of the stem is increased, even if the plant height remains unchanged, the lodging resistance can be significantly improved (Muszynska et al., 2021; Li et al., 2022; Nabatova et al., 2022). 2.3 Genetic variation and heritability analysis of lodging traits There are already many genetic differences related to lodging resistance in rye materials, and these abnormalities are associated with the tissue structure or chemical composition of the stem. Dwarfing genes like Ddw1, Ddw3 and the more recently reported Ddw4 are typical favorable alleles that can reduce plant height without affecting yield. Heritability analysis also shows that the effects of these genes are stable enough to be selected in breeding programs by relying on the markers associated with them. It is precisely because of such genetic diversity in germplasm resources that molecular marker-assisted selection is feasible in rye lodging resistance breeding (Kantarek et al., 2018; Jarosh and Relina, 2022). 3 Overview of Marker-Assisted Selection (MAS) in Resistance Breeding 3.1 Basic principles and breeding workflow of MAS In actual breeding, waiting until the crops grow up to see if they have resistance is too costly and too slow. Thus, the approach of MAS becomes attractive. It doesn't start from scratch but combines molecular markers with traditional breeding - it can identify which plants carry "good genes" at an early seedling stage. In this process, the first step is to identify the QTL or gene related to the target trait, and then develop closely linked DNA markers accordingly. The subsequent stages of genotyping, hybridization, backcrossing or pedigree selection are like "precise navigation", helping breeders more efficiently screen out the desired combination of traits. Especially when integrating multiple complex traits, this approach can save a lot of effort in phenotypic identification in the field (Boopathi, 2020; Misra and Singh, 2025). 3.2 Types of molecular markers (SSR, SNP, AFLP) and their characteristics Not all molecular markers are the same. Codominant types like SSR, although they have strong polymorphism and are suitable for analyzing genetic diversity or making linkage maps, have a slightly more complex operation process and are also relatively time-consuming. SNPS are different. They have many points, are stable, and are suitable for high throughput. They are especially suitable for large-scale projects and are currently the most widely used type of marker. Although AFLP can achieve whole-genome scanning without genomic information, it is a dominant marker with slightly weaker repeatability. It is suitable for initial screening but not very suitable for later detailed analysis. As for which marker to choose, it is not set in stone. It depends on the project goals, financial situation, and whether high throughput or higher resolution is required (Henkrar, 2020; Misra and Singh, 2025).
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