Unlocking the secrets of bolting resistance in Chinese cabbage
image: Flowering time of 'BR2OE' plants under different vernalization and photoperiod treatments.
Credit: Horticulture Research
In a groundbreaking discovery, researchers have identified a novel orphan gene, BOLTING RESISTANCE 2 (BR2), in Chinese cabbage, which plays a pivotal role in delaying bolting by regulating flowering time through the vernalization pathway. This breakthrough is set to transform breeding strategies for one of China’s most widely cultivated leafy vegetables, addressing a major agricultural challenge that compromises yield and quality in high-latitude and high-altitude regions. By unraveling the genetic mechanisms behind bolting resistance, this study paves the way for the development of more resilient Chinese cabbage varieties, ensuring improved crop performance and food security.
Chinese cabbage (Brassica rapa ssp. pekinensis) is a staple vegetable in China, prized for its high yield and nutritional value. However, premature bolting—where the plant transitions to flowering too early—remains a persistent issue, particularly in northern and high-altitude regions during spring. This early flowering disrupts head formation, leading to significant yield losses and economic setbacks for farmers. Bolting is controlled by complex genetic networks, including the vernalization pathway, which requires prolonged cold exposure to regulate flowering. Understanding the genetic basis of bolting resistance has, therefore, been a key focus for researchers seeking to enhance crop resilience.
A research team from Shenyang Agricultural University has now pinpointed BOLTING RESISTANCE 2 (BR2) as a crucial regulator of bolting resistance. Their study (DOI: 10.1093/hr/uhae216), published in Horticulture Research on July 30, 2024, provides compelling evidence that BR2 functions within the vernalization pathway, unlocking new genetic tools for breeding bolting-resistant Chinese cabbage varieties.
The study revealed that BR2 is an intronless orphan gene unique to Brassica rapa, encoding a cell membrane-localized protein. Researchers found that its expression is developmentally regulated and significantly elevated in bolting-resistant varieties while being downregulated in non-resistant ones. Functional analysis demonstrated that overexpression of BR2 in both Arabidopsis and Chinese cabbage led to a substantial delay in flowering, accompanied by increased expression of the flowering repressor gene FLC and decreased levels of key flowering integrators such as FT and SOC1. Further experiments showed that in vernalized Chinese cabbage, BR2 overexpression suppressed BrVIN3.b and BrFRI, while strongly upregulating BrFLC5, reinforcing its role in delaying floral transition. Transcriptomic analysis confirmed that BR2 primarily modulates the vernalization pathway, inhibiting key floral genes to extend the vegetative growth phase. These findings position BR2 as a promising genetic resource for breeding bolting-resistant Chinese cabbage, offering new avenues for crop improvement.
Dr. Xiaonan Li, a leading researcher on the project, emphasized the study’s significance: "The identification of BR2 as a bolting resistance regulator is a major step forward in our understanding of flowering control. This orphan gene’s function in the vernalization pathway provides a powerful tool for breeding more resilient Chinese cabbage varieties."
The implications of this discovery extend beyond scientific research. With bolting posing a significant challenge for farmers in temperate and high-altitude regions, incorporating BR2 into breeding programs could lead to varieties that maintain high yields and superior quality, even under challenging environmental conditions. This research not only deepens our knowledge of orphan genes but also delivers practical solutions for sustainable agriculture, ensuring a stable and productive future for Chinese cabbage cultivation.
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References
DOI
Original Source URL
https://doi.org/10.1093/hr/uhae216
Funding information
This work was supported by the National Natural Science Foundation of China (32302568), the China Agriculture Research System of MOF and MARA (CARS-12), and the National Natural Science Foundation of China (32272715).
About Horticulture Research
Horticulture Research is an open access journal of Nanjing Agricultural University and ranked number one in the Horticulture category of the Journal Citation Reports ™ from Clarivate, 2022. The journal is committed to publishing original research articles, reviews, perspectives, comments, correspondence articles and letters to the editor related to all major horticultural plants and disciplines, including biotechnology, breeding, cellular and molecular biology, evolution, genetics, inter-species interactions, physiology, and the origination and domestication of crops.