nsity. Thus, the greater relative abundance of Methylobacterium bacteria inside the SM5 stand (Figure 3B) is valuable for sapling resistance to oxidative stress. Members of the genus Pseudomonas are usually applied as biocontrol agents (De Vrieze et al., 2019; Palyzovet al., 2019; Liang et al., 2020), and these bacteria could influence leaf surface permeability and cuticle development (Xiao et al., 2004; Schreiber et al., 2005). Some members from the genus Sphingomonas are facultative phototrophs (Yabuuchi and Kosako, 2015) and are capable of suppressing infection by pathogenic bacteria (Innerebner et al., 2011). The aforementioned benefits suggest that the phyllosphere bacterial community may possibly supply a defensive barrier to guard Chinese fir from pathogens and oxidative strain triggered by higher light intensity.Metabolic Profile of Chinese Fir in Distinctive Development StagesChinese fir trees develop swiftly from the sapling for the juvenile stages. Fifty metabolites differed among the sapling and juvenile stands, whereas 26 metabolites differed involving every single stand age just after the juvenile stage (Supplementary Figure six). These outcomes recommend that the modify in nutrient requirements and the nutrient distribution approach might be reflected in the metabolite profiles (Zhou et al., 2016a). This age-relatedFrontiers in Plant Science | frontiersin.orgSeptember 2021 | Volume 12 | ArticleSun et al.Phyllosphere Bacterial Communities and Metabolomesvariation has been documented in Anatolian black pine (Pinus nigra subsp pallasiana) and Norway spruce [Picea abiess (L.) Karst.] (K tner et al., 2002; Turfan et al., 2018). The weakening with the strong relationship involving stand age and lots of metabolites in the overmature stage suggested that metabolic activities changed just after the tree attained maturity, even though nutrients for example nitrogen and phosphorus continue to accumulate in newly created needles (Zhou et al., 2016b). Quantities of benzenoids, which includes benzaldehyde, phenylacetaldehyde, and salicylic acid, have been substantially larger in the sapling stand (Supplementary Table two). These compounds show antimicrobial activity, which suggests that saplings biosynthesize a higher CYP1 Inhibitor supplier quantity of defense molecules in response to bacterial colonization (Whipps et al., 2008; Chaturvedi et al., 2012). Phenylalanine is the precursor of lignin and acts as a channel for carbon sequestered by photosynthesis (Pascual et al., 2016). The higher phenylalanine concentration in mature and overmature stands indicated that the needles contained a greater content material of lignin (Figure 7C). The content of Trigonelline also improved with stand age. Trigonelline could act as a nutrient supply, cell-cycle regulator, compatible solute, a bioactive substance for nyctinastic leaf movement, and also a signal transducer, and may play a CB1 Inhibitor drug function in detoxification of nicotinate and nicotinamide (Ashihara et al., 2015). Trigonelline accumulates in the course of leaf and fruit maturation in Coffea arabica Linn. (Zheng et al., 2004). For that reason, trigonelline or its correlated OTUs (e.g., the genera Pantoea, Cedecea SS01, Massilia, and Pseudomonas) may perhaps be valuable to estimate the degree of tree development in Chinese fir. Flavonoids, which function as antioxidants, may possibly guard leaves from ultraviolet irradiation damage. Such protection is vital for saplings since the individual leaves of saplings may be exposed to higher incident light intensity than the leaves of older trees (Ma et al., 2014). We observed that bacterial flavonoids synth
