2026-05-12 東京大学
花蜜微生物は蜜を酸性化することで花粉管を破裂させ栄養源を得る
＜関連情報＞
- https://www.a.u-tokyo.ac.jp/topics/topics_20260512-1.html
- https://www.nature.com/articles/s41467-026-72617-z
蜜に生息する細菌によるグルコース依存性酸性化戦略が花粉管の破裂を媒介する Glucose-dependent acidification strategy by nectar-dwelling bacteria mediates pollen tube burst
Yoshinobu Kato,Hiroki Miura,Seiji Takayama & Sota Fujii
Nature Communications Published:07 May 2026
DOI:https://doi.org/10.1038/s41467-026-72617-z
Abstract
Floral nectary gland serves as an ecological hub, including a habitat for microorganisms introduced by pollinators. Although nectar supplies abundant carbon sources, it is limited in nitrogen sources. To address this unbalanced nutritional condition, it is considered that some nectar-dwelling bacteria including those belong to genus Acinetobacter obtain nutrients from pollen protoplasm by inducing pollen tube burst. Here, using gas chromatography-mass spectrometry, we identify gluconic acid in A. nectaris and A. pollinis as the substance responsible for triggering pollen tube burst via acidification of the surrounding environments. Through whole-genome sequencing and functional analysis, we identify a membrane-bound pyrroloquinoline quinone (PQQ)-dependent glucose dehydrogenase which produces gluconic acid. Notably, nectar-dwelling Acinetobacter species consistently retain PQQ biosynthetic genes, and expression of the PQQ precursor peptide gene are upregulated in the presence of glucose, suggesting that these bacteria can synthesize PQQ and gluconic acid immediately upon entering the nectary gland. Taken together with previous findings, this glucose-dependent acidification is beneficial for both efficient carbon source utilization and nutrient landscape modification, a bacterial adaptive strategy well-suited to the competitive nectar environment.
