Plant hormone profiling of scion and rootstock incision sites and intra- and inter-family graft junctions in Nicotiana benthamiana

ABSTRACT

Many previous studies have suggested that various plant hormones play essential roles in the grafting process. In this study, to understand the plant hormones that accumulate in the graft junctions, whether these are supplied from the scion or rootstock, and how these hormones play a role in the grafting process, we performed a hormonome analysis that accumulated in the incision site of the upper plants from the incision as “ungrafted scion” and lower plants from the incision as “ungrafted rootstock” in Nicotiana benthamiana. The results revealed that indole-3-acetic acid (IAA) and gibberellic acid (GA), which regulate cell division; abscisic acid (ABA) and jasmonic acid (JA), which regulate xylem formation; cytokinin (CK), which regulates callus formation, show different accumulation patterns in the incision sites of the ungrafted scion and rootstock. In addition, to try discussing the differences in the degree and speed of each event during the grafting process between intra- and inter-family grafting by determining the concentration and accumulation timing of plant hormones in the graft junctions, we performed hormonome analysis of graft junctions of intra-family grafted plants with N. benthamiana as scion and Solanum lycopersicum as rootstock (Nb/Sl) and inter-family grafted plants with N. benthamiana as scion and Arabidopsis thaliana as rootstock (Nb/At), using the ability of Nicotiana species to graft with many plant species. The results revealed that ABA and CK showed different accumulation timings; IAA, JA, and salicylic acid (SA) showed similar accumulation timings, while different accumulated concentrations in the graft junctions of Nb/Sl and Nb/At. This information is important for understanding the molecular mechanisms of plant hormones in the grafting process and the differences in molecular mechanisms between intra- and inter-family grafting.

KEYWORDS:

• Nicotiana benthamiana
• intrafamily grafting
• interfamily grafting
• hormonome analysis
• auxin
• cytokinin
• gibberellic acid

Acknowledgments

We thank Aiko Ishiwata for technical assistance. We also would like to thank Editage (www.editage.jp) for English language editing.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

All data are fully available without restriction.

Additional information

Funding

This research was supported by the research program on the development of innovative technology grants (28001A, 28001AB) from the Project of the Bio-oriented Technology Research Advancement Institution (BRAIN), Grants-in-Aid for Scientific Research (KAKENHI 18H03950, 20K20372, 21K19111, 21H02184) from the Japan Society for the Promotion of Science (JSPS) to Katsuhiro Shiratake and Michitaka Notaguchi, Grant-in-Aid for JSPS Fellows (20J13580) from the JSPS and Graduate Program of Transformative Chem-Bio Research (GTR) in Nagoya University supported by MEXT (WISE Program) to Kawaguchi Kohei.The funders played no role in the study design, data collection and analysis, publication decisions, or manuscript preparation.