Beijing Key Laboratory of Maize DNA Fingerprinting and Molecular Breeding, Maize Research Center, Beijing Academy of Agriculture & Forestry Sciences (BAAFS), Shuguang Garden Middle Road No. 9, Haidian District, Beijing, 100097, China.
Beijing Key Lab of Digital Plant, Beijing Research Center for Information Technology in Agriculture, Beijing Academy of Agriculture and Forestry Sciences (BAAFS), Shuguang Garden Middle Road No. 11, Haidian District, Beijing, 100097, China.
BMC Plant Biol. 2020 Nov 11;20(1):515. doi: 10.1186/s12870-020-02728-2.
Stalk fracture caused by strong wind can severely reduce yields in maize. Stalks with higher stiffness and flexibility will exhibit stronger lodging resistance. However, stalk flexibility is rarely studied in maize. Stalk fracture of the internode above the ear before tasseling will result in the lack of tassel and pollen, which is devastating for pollination in seed production. In this study, we focused on stalk lodging before tasseling in two maize inbred lines, JING724 and its improved line JING724A1 and their F population.
JING724A1 showed a larger stalk fracture angle than JING724, indicating higher flexibility. In addition, compared to JING724, JING724A1 also had longer and thicker stalks, with a conical, frustum-shaped internode above the ear. Microscopy and X-ray microcomputed tomography of the internal stalk architecture revealed that JING724A1 had more vascular bundles and thicker sclerenchyma tissue. Furthermore, total soluble sugar content of JING724A1, especially the glucose component, was substantially higher than in JING724. Using an F population derived from a JING724 and JING724A1 cross, we performed bulk segregant analysis for stalk fracture angle and detected one QTL located on Chr3: 14.00-19.28 Mb. Through transcriptome data analysis and ∆ (SNP-index), we identified two candidate genes significantly associated with high stalk fracture angle, which encode a RING/U-box superfamily protein (Zm00001d039769) and a MADS-box transcription factor 54 (Zm00001d039913), respectively. Two KASP markers designed from these two candidate genes also showed significant correlations with stalk fracture angle.
The internode shape and glucose content are possibly correlated with stalk flexibility in maize. Two genes in the detected QTL are potentially associated with stalk fracture angle. These novel phenotypes and associated loci will provide a theoretical foundation for understanding the genetic mechanisms of lodging, and facilitate the selection of maize varieties with improved flexibility and robust lodging resistance.
强风导致的玉米茎秆折断会严重降低玉米产量。具有更高刚性和柔韧性的茎秆将表现出更强的抗倒伏能力。然而，玉米茎秆柔韧性很少被研究。抽雄前穗位以上节间的茎秆折断会导致穗缺失和花粉缺乏，这对制种授粉是毁灭性的。在这项研究中，我们专注于两个玉米自交系 JING724 及其改良系 JING724A1 及其 F 群体在抽雄前的茎秆倒伏。
JING724A1 的茎秆折断角大于 JING724，表明柔韧性更高。此外，与 JING724 相比，JING724A1 还具有更长、更粗的茎秆，穗位以上的节间呈圆锥形、截头圆锥形。茎秆内部结构的显微镜和 X 射线微计算机断层扫描显示，JING724A1 具有更多的维管束和更厚的厚壁组织。此外，JING724A1 的总可溶性糖含量，特别是葡萄糖成分，显著高于 JING724。利用 JING724 和 JING724A1 杂交得到的 F 群体，我们对茎秆折断角进行了 bulk segregant 分析，检测到一个位于 Chr3：14.00-19.28 Mb 的 QTL。通过转录组数据分析和 ∆（SNP-index），我们鉴定出与高茎秆折断角显著相关的两个候选基因，分别编码一个 RING/U-box 超级家族蛋白（Zm00001d039769）和一个 MADS 框转录因子 54（Zm00001d039913）。从这两个候选基因设计的两个 KASP 标记也与茎秆折断角呈显著相关。
玉米节间形状和葡萄糖含量可能与茎秆柔韧性相关。检测到的 QTL 中的两个基因可能与茎秆折断角相关。这些新的表型和相关位点将为理解倒伏的遗传机制提供理论基础，并有助于选择具有改善柔韧性和抗倒伏能力的玉米品种。
