Phenotypic advantages and improved genomic stability following selection in advanced selfing-generations of <i>Brassica</i> allohexaploids

Yan Niu; Rui Yang; Zelong Li; Zhengxuan Huo; Shihao Chang; Entang Tian; Han Qin; Wallace A. Cowling; Kadambot H. M. Siddique; Annaliese S. Mason; Sheng Chen; Jun Zou

doi:10.1016/j.jgg.2025.03.004

Volume 52 Issue 6

Jun. 2025

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Phenotypic advantages and improved genomic stability following selection in advanced selfing-generations of Brassica allohexaploids

doi: 10.1016/j.jgg.2025.03.004

a. National Key Laboratory of Crop Genetic Improvement, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, Hubei 430070, China;
b. Department of Agronomy, College of Agriculture, Guizhou University, Guiyang, Guizhou 550025, China;
c. The UWA Institute of Agriculture, The University of Western Australia, Perth, WA 6009, Australia;
d. Plant Breeding Department, University of Bonn, Bonn 53115, Germany

Funds:

This work was supported by the Sino-German Research Project (GZ 1362), Grains Research and Development Corporation International Visiting Fellowship (UWA2406-010BGX), the National Natural Science Foundation of China (32171982), and the Fundamental Research Funds for the Central Universities of the Chinese Government (2662023PY004).

Received Date: 2024-11-12
Accepted Date: 2025-03-05
Rev Recd Date: 2025-03-05

Available Online: 2025-07-11

Publish Date: 2025-03-14

Abstract

Abstract

Allopolyploids often exhibit advantages in vigor and adaptability compared to diploids. A long-term goal in the economically important Brassica genus has been to develop a new allohexaploid crop type (AABBCC) by combining different diploid and allotetraploid crop species. However, early-generation allohexaploids often face challenges like unstable meiosis and low fertility, and the phenotypic performance of these synthetic lines has rarely been assessed. This study analyzes agronomic traits, fertility, and genome stability in A^rA^rB^cB^cC^cC^c lines derived from four crosses between B. carinata and B. rapa after 9–11 selfing generations. Our results demonstrate polyploid advantage in vigor and seed traits, considerable phenotypic variation, and high fertility and genome stability. Meanwhile, parental genotypes significantly influence outcomes in advanced allohexaploids. Structural variants, largely resulting from A–C homoeologous exchanges, contribute to genomic variation and influence hexaploid genome stability, with the A sub-genome showing the highest variability. Both positive and negative impacts of SVs on fertility and seed weight are observed. Pseudo-euploids, frequently appearing, do not significantly affect fertility or other agronomic traits compared to euploids, indicating a potential pathway toward a stable allohexaploid species. These findings provide insights into the challenge and potential for developing an adaptable and stable Brassica hexaploid through selection.
- Brassica species,
- Synthetic allohexaploid,
- Homoeologous exchange,
- Genome stability,
- Polyploid advantage,
- Structural variants

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