Hormonal and transcriptomic signatures of scion-associated early growth suppression in Camellia oleifera

A multi-stage study of graft healing found that ‘Changlin 53’ scions of Camellia oleifera had delayed callus organization and vascular reconnection than fast-growing ‘Changlin 18’ scions placed on the same rootstock background. The suppressed seedlings also showed less shoot growth, greater root-to-shoot ratios and shorter but thicker roots. Hormone measurements and transcriptome sequencing linked this phenotype to stage-specific changes in plant signals, stress responses, metabolism and gene activity, suggesting that delayed transition from wound response to regenerative growth may contribute to reduced first-year vigor under the tested conditions.

The experiment compared ‘Changlin 53’ scions with ‘Changlin 18’ scions grafted onto a common ‘Changlin 18’ half-sib rootstock. Investigators examined graft healing through histology, hormone profiling and transcriptome sequencing at five post-grafting stages. The design allowed them to compare structural recovery with changes in auxin, cytokinin, jasmonate, salicylic acid and abscisic acid, as well as with broader transcriptional activity. Although the slow-growth phenotype had previously been reported, the processes at the graft interface remained poorly understood. The researchers also compared seedling growth, biomass allocation and root morphology between the two graft combinations.

‘Changlin 18’ rootstocks carrying ‘Changlin 53’ scions produced seedlings with significantly lower height, shoot fresh weight and shoot dry weight than the ‘Changlin 18’/‘Changlin 18’ combination. Their fresh and dry root-to-shoot ratios were significantly higher. Ground diameter, root fresh weight and root dry weight did not differ significantly between the groups. The suppressed seedlings also had a significantly shorter total root length but a significantly larger average root diameter, while root surface area and root volume did not differ significantly. These measurements indicate a shift in biomass allocation and altered root architecture associated with the slow-growing scion, although they do not establish what caused that shift.

The transcriptomic comparison indicated that the two scion genotypes differed not only in which genes responded but also in how those responses were organized over time. ‘Changlin 53’ displayed more stage-specific and less temporally coordinated differential expression than ‘Changlin 18’. Cell-cycle-related genes were suppressed early in healing. Intermediate stages showed metabolic and defense imbalance, while the middle-to-late period brought increased expression of ERF stress-responsive genes alongside reduced expression of Hsp70, Hsp90, small heat-shock protein and protein quality-control genes. At later stages, phenylpropanoid metabolism and DOF transcription factors were upregulated, as were specific BBX genes. This sequence is consistent with a prolonged wound-responsive state and a delayed shift toward regenerative growth, but the analysis does not prove that any one gene or pathway causes the observed suppression.

Hormone profiling revealed genotype-dependent differences in the timing of auxin, cytokinin, jasmonate, salicylic acid and abscisic acid dynamics during graft healing. The two scion genotypes therefore did not follow the same hormonal sequence at the interface. The researchers identified CYP86A22 and cell-wall-remodeling genes, including PME12, PME20 and PME41, as candidates linking hormonal signals with delayed interface remodeling. They proposed a working model in which prolonged wound responsiveness and delayed graft-interface reconstruction contribute to reduced early vigor in ‘Changlin 53’ scions. The findings are associated with the tested rootstock background and cultivar pairing; they do not demonstrate that delayed healing is the sole cause of slow growth in C. oleifera across grafting environments.

Subject of Research: Hormonal and transcriptomic signatures associated with scion-dependent early growth suppression in grafted Camellia oleifera

Article Title: Hormonal and transcriptomic signatures of scion-associated early growth suppression in Camellia oleifera

Article References: Long, W., Wang, K., Lyu, L., & Xiong, Y. (2026). Hormonal and transcriptomic signatures of scion-associated early growth suppression in Camellia oleifera. BMC Plant Biology. https://doi.org/10.1186/s12870-026-10191-8

Image Credits: AI Generated

DOI: 10.1186/s12870-026-10191-8

Keywords: Camellia oleifera, graft healing, growth suppression, plant hormones, transcriptomics, vascular reconnection, wound response, cell-wall remodeling, Hormonal, transcriptomic, signatures, scion-associated