Epidermal (A) flavonol and (B) anthocyanin contents measured at the adaxial and abaxial sides of leaves of Vaccinium myrtillus, Soldanella carpatica (overwintered), and Homogyne alpina growing in the Tatra Mountains, at different sites: understorey (Jaworzynka valley, 1080 m asl, 1125 m asl), clearing (Jaworzynka Valley, 1080 m asl, 1125 m asl), subalpine (Hala Gasienicowa, 1615 m asl), and peak alpine (Liliowe Pass, 1970 m asl) sites. Leaves were measured with Dualex Scientific + (Force-A, Paris-Sud, France) for 20 plants of each species at a given site.

Change in transmittance in the PAR (400 - 700 nm) of leaves in response to 1 h illumination with high blue light (peak at ca. 450 nm, 100 umol/m^2/s). Experiments performed on dark adapted leaves of Vaccinium myrtillus, Homogyne alpina (new leaves) and Soldanella carpatica (overwintered leaves) collected at different sites in the Tatra Mountains:understorey (Jaworzynka Valley, 1080 m asl, 1125 m asl), clearing (Jaworzynka Valley, 1080 m asl, 1125 m asl), subalpine (Hala Gasienicowa, 1615 m asl), and peak alpine (Liliowe Pass, 1970 m asl) sites. Measurements of transmittance were recorded from the adaxial leaf side using a Jaz Spectro-Clip (Ocean Optics, Dunedin, USA). A xenon light source provided a pulse of light at a trigger rate of 10 ms.

Epidermal (A) flavonol and (B) anthocyanin contents measured at the adaxial and abaxial sides of leaves of Vaccinium myrtillus, Soldanella carpatica (overwintered), and Homogyne alpina growing in the Tatra Mountains, at different sites: understorey (Jaworzynka valley, 1080 m asl, 1125 m asl), clearing (Jaworzynka Valley, 1080 m asl, 1125 m asl), subalpine (Hala Gasienicowa, 1615 m asl), and peak alpine (Liliowe Pass, 1970 m asl) sites. Leaves were measured with Dualex Scientific + (Force-A, Paris-Sud, France) for 20 plants of each species at a given site.

Measurements recorded with the Leaf State Analyser (Waltz) device, used to estimate apparent content of flavonols and anthocyanins in adaxial epidermis and total leaf chlorophyll content measured in June or July for Vaccinium myrtillus, Soldanella carpatica, and Homogyne alpina. Measurements were formed at the understorey (Jaworzynka Valley, 1080 m asl, 1125 m asl), clearing (Jaworzynka Valley, 1080 m asl, 1125 m asl), subalpine (Hala Gasienicowa, 1615 m asl), and peak alpine sites (Liliowe Pass, (1970 m asl) in the Tatra Mountains, Poland.

Measurements recorded with the Leaf State Analyser (Waltz) device, used to estimate apparent content of flavonols and anthocyanins in adaxial epidermis and total leaf chlorophyll content measured in June or July for Vaccinium myrtillus, Soldanella carpatica, and Homogyne alpina. Measurements were formed at the understorey (Jaworzynka Valley, 1080 m asl, 1125 m asl), clearing (Jaworzynka Valley, 1080 m asl, 1125 m asl), subalpine (Hala Gasienicowa, 1615 m asl), and peak alpine sites (Liliowe Pass, (1970 m asl) in the Tatra Mountains, Poland.

Change in transmittance in the PAR (400 - 700 nm) of leaves in response to 1 h illumination with high blue light (peak at ca. 450 nm, 100 umol/m^2/s). Experiments performed on dark adapted leaves of Vaccinium myrtillus, Homogyne alpina (new leaves) and Soldanella carpatica (overwintered leaves) collected at different sites in the Tatra Mountains:understorey (Jaworzynka Valley, 1080 m asl, 1125 m asl), clearing (Jaworzynka Valley, 1080 m asl, 1125 m asl), subalpine (Hala Gasienicowa, 1615 m asl), and peak alpine (Liliowe Pass, 1970 m asl) sites. Measurements of transmittance were recorded from the adaxial leaf side using a Jaz Spectro-Clip (Ocean Optics, Dunedin, USA). A xenon light source provided a pulse of light at a trigger rate of 10 ms.

Data 1. The data showing the effects of the light conditions (two levels: only visible light /VIS/, visible light supplemented with UV-A /VIS + UVA/), the plant organ (two levels: roots, shoots) and inoculation status (two levels: inoculated vs non-inoculated) on the log-transformed ratio of fungal DNA to Arabidopsis DNA, measured with qPCR. Plants were inoculated with Paraphoma chrysanthemicola, Phomopsis columnaris, Diaporthe eres, Mucor sp. or Sporobolomyces ruberrimus.Data 2. The data showing the effects of endophyte inoculation (six levels, including the mock-inoculated control) and light conditions (two levels: only visible light /VIS/, visible light supplemented with UV-A /VIS + UVA/) on the following properties measured for Arabidopsis plants: root system length, average volume, average diameter, fresh weight of roots, fresh weight of shoots and shoot anthocyanin content.Data 3. The data showing the effects of endophyte inoculation (six levels, including the mock-inoculated control) and light conditions (two levels: only visible light /VIS/, visible light supplemented with UV-A /VIS + UVA/) on the log-transformed relative level of the following transcripts in Arabidopsis plants: CHS1, PAL1, ICS1, PDF1.2, CRY1, CRY2, PHOT1, PHOT2, UVR8.Data 4. The data showing the effects of endophyte inoculation (two levels, the mock-inoculated control and inoculation with Sporobolomyces ruberrimus), light conditions (two levels, only visible light /VIS/ or visible light supplemented with UV-A /VIS + UVA/) and the interaction between endophyte presence and light conditions on the leaf flavonol and chlorophyll content indices measured with Dualex, as well as the lipid peroxidation level examined with the MDA assay.Data 5. The data showing the effects of light conditions (two levels, only visible light /VIS/ or visible light supplemented with UV-A /VIS + UVA/) on the following properties measured for non-inoculated Arabidopsis plants on the 9-th day of growth: root system length volume, average diameter.Data 6. The data showing the effects of the light conditions (two levels: only visible light /VIS/, visible light supplemented with UV-A /VIS + UVA/), plant line (three levels: wild type, fah1-2 and tt4-11) and inoculation status (two levels: inoculated vs non-inoculated) on the log-transformed ratio of fungal DNA to Arabidopsis DNA, measured with qPCR. Plants were inoculated with Paraphoma chrysanthemicola or Sporobolomyces ruberrimus.Data 7. The data showing the effects of endophyte inoculation (three levels, the mock-inoculated control and inoculation with either Paraphoma chrysanthemicola or Sporobolomyces ruberrimus), light conditions (two levels, only visible light /VIS/ or visible light supplemented with UV-A /VIS + UVA/), plant line (three levels, wild type, tt4-11 and fah1-2) and their two- and three-way interactions on fresh shoot and root weight 128 h after inoculation, as well as the increase in the main root length within 100 h after inoculation.Data 8. The data showing the effects of endophyte inoculation (two levels, the mock-inoculated control and inoculation with Sporobolomyces ruberrimus), light conditions (two levels, only visible light /VIS/ or visible light supplemented with UV-A /VIS + UVA/) and the interaction between endophyte presence and light conditions on the leaf photosynthetic parameters. Slow kinetics with induction curve and light curves of chlorophyll were measured with Dual-PAM-100 fluorimeter.

Data 1. The data showing the effects of the light conditions (two levels: only visible light /VIS/, visible light supplemented with UV-A /VIS + UVA/), the plant organ (two levels: roots, shoots) and inoculation status (two levels: inoculated vs non-inoculated) on the log-transformed ratio of fungal DNA to Arabidopsis DNA, measured with qPCR. Plants were inoculated with Paraphoma chrysanthemicola, Phomopsis columnaris, Diaporthe eres, Mucor sp. or Sporobolomyces ruberrimus.Data 2. The data showing the effects of endophyte inoculation (six levels, including the mock-inoculated control) and light conditions (two levels: only visible light /VIS/, visible light supplemented with UV-A /VIS + UVA/) on the following properties measured for Arabidopsis plants: root system length, average volume, average diameter, fresh weight of roots, fresh weight of shoots and shoot anthocyanin content.Data 3. The data showing the effects of endophyte inoculation (six levels, including the mock-inoculated control) and light conditions (two levels: only visible light /VIS/, visible light supplemented with UV-A /VIS + UVA/) on the log-transformed relative level of the following transcripts in Arabidopsis plants: CHS1, PAL1, ICS1, PDF1.2, CRY1, CRY2, PHOT1, PHOT2, UVR8.Data 4. The data showing the effects of endophyte inoculation (two levels, the mock-inoculated control and inoculation with Sporobolomyces ruberrimus), light conditions (two levels, only visible light /VIS/ or visible light supplemented with UV-A /VIS + UVA/) and the interaction between endophyte presence and light conditions on the leaf flavonol and chlorophyll content indices measured with Dualex, as well as the lipid peroxidation level examined with the MDA assay.Data 5. The data showing the effects of light conditions (two levels, only visible light /VIS/ or visible light supplemented with UV-A /VIS + UVA/) on the following properties measured for non-inoculated Arabidopsis plants on the 9-th day of growth: root system length volume, average diameter.Data 6. The data showing the effects of the light conditions (two levels: only visible light /VIS/, visible light supplemented with UV-A /VIS + UVA/), plant line (three levels: wild type, fah1-2 and tt4-11) and inoculation status (two levels: inoculated vs non-inoculated) on the log-transformed ratio of fungal DNA to Arabidopsis DNA, measured with qPCR. Plants were inoculated with Paraphoma chrysanthemicola or Sporobolomyces ruberrimus.Data 7. The data showing the effects of endophyte inoculation (three levels, the mock-inoculated control and inoculation with either Paraphoma chrysanthemicola or Sporobolomyces ruberrimus), light conditions (two levels, only visible light /VIS/ or visible light supplemented with UV-A /VIS + UVA/), plant line (three levels, wild type, tt4-11 and fah1-2) and their two- and three-way interactions on fresh shoot and root weight 128 h after inoculation, as well as the increase in the main root length within 100 h after inoculation.Data 8. The data showing the effects of endophyte inoculation (two levels, the mock-inoculated control and inoculation with Sporobolomyces ruberrimus), light conditions (two levels, only visible light /VIS/ or visible light supplemented with UV-A /VIS + UVA/) and the interaction between endophyte presence and light conditions on the leaf photosynthetic parameters. Slow kinetics with induction curve and light curves of chlorophyll were measured with Dual-PAM-100 fluorimeter.

Recordings of changes in bidirectional reflectance and hemispherical transmittance in plants collected in the field: Draba verna, Stellaria media, Tussilago farfara, and Vaccinium myrtillus.The sun-exposed side of leaves (adaxial – Arabidopsis, Draba, Stellaria; abaxial - Tussilago) or stems (Vaccinium) were irradiated with low (0.1) or high blue light (100 µmol·m^-2·s^-1) or mock irradiation. The angle of incidence of beams was 55° while the angle of observation was 0° (diffuse reflectance recorded).Binary files can be opened with BeamJ (https://github.com/pawelHerm/beamJ/tree/master/BeamJ), while the CSV files can be opened with a text editor or MS Excel.

Reflectance single polarizer setup: Time courses of changes in red-light bidirectional reflectance induced by 1 h irradiation with low (0.1 µmol·m^-2·s^-1) or high (100 µmol·m^-2·s^-1) blue light of the adaxial surface of rosette leaves of 5-week-old Arabidopsis plants. Measurements were recorded for wild-type (WT), glabra1, phot1, phot2, phot1phot2, and jac1 mutants. The angle of incidence of the measuring and actinic beams was 40° or 55°. The detector was positioned at the angle of 0° (the detector normal parallel to the leaf normal) or either -40° (when incidence at 40°) or -55° (when incidence at 55°). The transmission axis of the polarizer was either parallel (P) or perpendicular (S) to the plane of incidence.Reflectance two polarizer setup: Time courses of the polarized red-light bidirectional reflectance induced by 1 h irradiation with high blue light (100 µmol·m^-2·s^-1) of the adaxial surface of rosette leaves of 5-week-old wild-type and phot1phot2 Arabidopsis plants. The blue actinic and red measuring beams impinged the adaxial leaf surface at the angle of 55°. For measurements of diffuse reflectance, the detector was positioned at 0° to the leaf’s normal. For measurements of combined specular and diffuse reflectance, the detector was positioned at -55°. Four possible combinations of the orientation (P/S) of the polarizers in front of the measuring light source and the detector were examinedBinary files can be opened with BeamJ (https://github.com/pawelHerm/beamJ/tree/master/BeamJ), while the CSV files can be opened with a text editor or MS Excel.