Rapeseed is a cornerstone of global vegetable oil production, accounting for 13%–16% of the world's supply. However, the widespread adoption of high-density direct seeding, while boosting yield potential, has dramatically increased lodging risk–where stems bend or break, causing harvest losses of 20%–46%. While lignin and cellulose have long been the focus of stem strength research, a key component in the cell wall has been overlooked: pectin.
Pectin is a complex carbohydrate whose structure can be modified by calcium ions. Calcium helps cross-link pectin chains, forming a reinforcing "egg-box" structure within the cell wall that enhances mechanical strength. Yet, the precise mechanism by which calcium coordinates pectin metabolism to synergistically improve both lodging resistance and yield has remained unclear.
To that end, researchers from the Rapeseed Cultivation and Physiology Team at Huazhong Agricultural University systematically revealed the dual role of calcium and offered a new strategy for rapeseed breeding and cultivation.
The study delineates the complete pathway of calcium action: from macroscopically improving stem structure, to microscopically remodeling cell wall components, and to molecularly regulating gene networks—ultimately strengthening the stem from the inside out to achieve superior traits.
“We've found that calcium is more than just a nutrient; it's a master regulator,” explains corresponding author Jing Wang. “It acts both as a building material to construct a stronger stem framework and as a signaling molecule to finely tune the cell wall assembly process.”
Through multi-environment field trials, the researchers demonstrated that calcium application significantly enhanced stem strength while increasing the average number of siliques per plant by nearly 30%, successfully breaking the traditional trade-off between high yield and lodging resistance.
“We found that the effectiveness of calcium fertilization is significantly influenced by environmental and agronomic conditions,” adds Wang. “In dryland soils, the benefits of stem strengthening, root neck thickening and yield increase are most comprehensive under conventional high-density planting conditions. This provides crucial guidance for precision calcium management based on soil type and planting density.”
At the molecular level, the team found that calcium treatment increases the content of specific pectins primed for cross-linking and reduces their degree of methylation, making them more receptive to forming the rigid "egg-box" structure. Genetically, calcium upregulates key enzyme genes responsible for initiating pectin cross-linking while downregulating their inhibitors and degrading enzymes. To confirm this pathway, the researchers used CRISPR/Cas9 to knock out a key pectin-modifying gene ( BnaPME35 ).
“The mutant plants exhibited significantly weaker stems,” says Wang. “Calcium treatment was able to partially restore proper pectin modification and stem strength in these plants.”
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Author contact:
Jing Wang, wangjing@mail.hzau.edu.cn.
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The Crop Journal
Experimental study
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Calcium application synergizes lodging resistance and yield potential in rapeseed by cell wall strengthening and photosynthesis
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.