Maize Genomics and Genetics 2024, Vol.15, No.4, 171-181 http://cropscipublisher.com/index.php/mgg 175 Figure 3 Positional cloning of UPA2Adopted from (Adopted from Tian et al., 2019) Image caption: (A): QTL mapping for middle leaf angle in the maize–teosinte BC2S3 population. LOD, logarithm of odds. UPA2 and UPA1 are the largest- and second-largest leaf angle QTL, respectively. The dashed gray line at LOD of 5 indicates the threshold of claiming significant QTLs. (B) Gross morphologies of UPA2-NILW22 and UPA2-NIL8759. The white arrows indicate the lower, middle, and upper leaves in which leaf angle was scored. Scale bars, 20 cm. (C) Comparison of leaf angle in lower, middle, and upper leaves between UPA2-NILW22 and UPA2-NIL8759. (D) Scanning electron microscopy analysis of the ligular region of UPA2-NILW22 and UPA2-NIL8759. The ligular band and the mature auricle region are indicated by white dashed lines. Scale bars, 3 mm (top) and 500 mm (bottom). (E) Comparison of the width of the ligular band and auricle margin between UPA2-NILW22 and UPA2-NIL8759. (F) Cross-sections of the mature ligular region of UPA2-NILW22 and UPA2-NIL8759. Top shows the abaxial side and bottom shows the adaxial side. Scale bars, 100 mm; (G) Comparison of number of the abaxial sclerenchyma cell layers (left) and the adaxial sclerenchyma cell layers (right) between UPA2-NILW22 and UPA2-NIL8759. (H) Location of UPA2 on maize chromosome 2; CEN, centromere; (I) Fine mapping of UPA2 using an NIL population (n = 3180). The number of recombinants between adjacent markers is indicated below the linkage map. (J) Progeny testing of recombinants delimited UPA2 to a 240-bp noncoding region (red lines). The graphical genotypes of the five critical recombinants are shown on the left. White, black, and gray segments indicate regions homozygous for W22, regions homozygous for 8759, and heterozygous regions, respectively. The bar graphs on the right compare middle leaf angle between homozygous recombinants and homozygous nonrecombinants within each recombinant-derived F3 family. Black and white bars represent homozygous progenies that inherited the 8759 and W22 chromosome from the parental recombinant, respectively. The 240-bp region of UPA2 is located 9540 bp upstream of the start codon (ATG) of GRMZM2G102059 (ZmRAVL1). Pink and gray regions indicate the exon and untranslated regions (UTR), respectively. Values are means ± SD. **P<0.01 (Student’s t test). N.S., not significant (Adopted from Tian et al., 2019) In summary, the genetic contributions of teosinte to maize are profound, with key loci such as tb1 and UPA2 playing significant roles in domestication. Traits inherited from teosinte, including kernel composition and plant architecture, have been crucial for maize improvement. Modern genetic analysis techniques continue to uncover the complex genetic architecture of teosinte, providing valuable insights and resources for future maize breeding efforts. 5 Techniques for Utilizing Teosinte in Maize Breeding 5.1 Hybridization and Backcrossing Hybridization and backcrossing are traditional techniques used to introduce desirable traits from teosinte into maize. By crossing teosinte with elite maize lines, researchers can create hybrids that combine the beneficial traits
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