Arabidopsis plants grown in the field and climate chambers significantly differ in leaf morphology and photosystem components

Abstract

Background: Plants exhibit phenotypic plasticity and respond to differences in environmental conditions by acclimation. We have systematically compared leaves of Arabidopsis thaliana plants grown in the field and under controlled low, normal and high light conditions in the laboratory to determine their most prominent phenotypic differences.

Results: Compared to plants grown under field conditions, the "indoor plants" had larger leaves, modified leaf shapes and longer petioles. Their pigment composition also significantly differed; indoor plants had reduced levels of xanthophyll pigments. In addition, Lhcb1 and Lhcb2 levels were up to three times higher in the indoor plants, but differences in the PSI antenna were much smaller, with only the low-abundance Lhca5 protein showing altered levels. Both isoforms of early-light-induced protein (ELIP) were absent in the indoor plants, and they had less non-photochemical quenching (NPQ). The field-grown plants had a high capacity to perform state transitions. Plants lacking ELIPs did not have reduced growth or seed set rates, but their mortality rates were sometimes higher. NPQ levels between natural accessions grown under different conditions were not correlated.

Conclusion: Our results indicate that comparative analysis of field-grown plants with those grown under artificial conditions is important for a full understanding of plant plasticity and adaptation.

Figure 1

Phenotypic plasticity of Arabidopsis thaliana rosettes in different growth regimes. Plants were grown in climate chambers under Low, Normal or High Light (LL, NL and HL; 30, 300 and 600 μmol quanta m^-2 s^-1, respectively) and under field conditions.

Figure 2

Rosette leaf complements of Arabidopsis thaliana plants under different growth regimes. Plants were grown in climate chambers under Low, Normal or High Light (LL, NLand HL; 30, 300 and 600 μmol quanta m^-2 s^-1, respectively) and under field conditions.

Figure 3

Variation in leaf traits of Arabidopsis thaliana plants under different growth regimes. Plants were grown in climate chambers under Low, Normal or High Light (LL, NL and HL; 30, 300 and 600 μmol quanta m^-2 s^-1, respectively) and under field conditions. A Leaf area (mm²), B length (mm), C width:length ratio, D width (n = 10). Different lower case letters above bars indicate significant differences (p < 0.001), according to separate Duncan's new multiple range tests followed by contrast analysis (indoor vs. field plants) applied to data presented in each column.

Figure 4

Variation in chlorophyll in Arabidopsis thaliana leaves in different growth regimes. Plants were grown in climate chambers under Low, Normal or High Light (LL, NL and HL; 30, 300 and 600 μmol quanta m^-2 s^-1, respectively) and under field conditions. A Total chlorophyll content and B Chl a/b ratio were determined from leaf discs (n = 3 pools of leaves each from 5-15 plants). Different lower case letters above bars indicate significant differences (p < 0.001), according to separate Duncan's new multiple range tests followed by contrast analysis (indoor vs. field plants) applied to data presented in each column.

Figure 5

PSI protein composition of Arabidopsis thaliana in different growth regimes. Plants were grown in climate chambers under Low, Normal or High Light (LL, NL and HL; 30, 300 and 600 μmol quanta m^-2 s^-1, respectively) and under field conditions. A Results of immunoblot analysis of thylakoid membranes, probed with antibodies against Lhca1, Lhca2, Lhca3 Lhca4 and Lhca5. Lanes were loaded with 1.0 μg chlorophyll. B Quantification of immunoblot data. Error bars indicate SE (n = 3 pools of leaves each from 5-15 plants), the relative abundances of proteins were normalized to the data for field-grown plants. Different lower case letters above bars indicate significant differences (p < 0.001), according to separate Duncan's new multiple range tests followed by contrast analysis (indoor vs. field plants) applied to data presented in each column.

Figure 6

PSII protein composition of Arabidopsis thaliana in different growth regimes. Plants were grown in climate chambers under Low, Normal or High Light (LL, NL and HL; 30, 300 and 600 μmol quanta m^-2 s^-1, respectively) and under field conditions. A Results of immunoblot analysis of thylakoid membranes probed with antibodies against Lhcb1, Lhcb2, Lhcb3, Lhcb4, Lhcb5, Lhcb6, PsbA (D1), PsbD (D2) and PsbS. Lanes were loaded with 1.0 μg chlorophyll. B Quantification of immunoblot data. Error bars indicate SE, n = 3 pools of leaves each from 5-15 plants. The relative abundances of peptides were normalized to the data for field-grown plants. Different lower case letters above bars indicate significant differences (p < 0.001), according to separate Duncan's new multiple range tests followed by contrast analysis (indoor vs. field plants) applied to data presented in each column.

Figure 7

ELIPI and ELIPII content of Arabidopsis thaliana in different growth regimes. Plants were grown in climate chambers under Low, Normal or High Light (LL, NL and HL; 30, 300 and 600 μmol quanta m^-2 s^-1, respectively) and under field conditions. Results of immunoblot analysis of thylakoid membranes probed with antibodies against ELIPI and ELIPII. Lanes were loaded with 1.0 μg chlorophyll. n = 3 pools of leaves each from 5-15 plants.

Figure 8

Photosynthetic functions in Arabidopsis thaliana in different growth regimes. Plants were grown in climate chambers under Low, Normal or High Light (LL, NL and HL; 30, 300 and 600 μmol quanta m^-2 s^-1, respectively) and under field conditions. Photosynthetic function was assessed in dark-adapted leaves. Light response curves are shown for (A) Fv/Fm (B) non-photochemical quenching (NPQ) and (C) qP. Data represent means ± SE for leaves from at least six plants grown in two batches. Different lower case letters above bars indicate significant differences (p < 0.001), according to separate Duncan's new multiple range tests followed by contrast analysis (indoor vs. field plants) applied to data presented in each column.

Figure 9

Phenotypic plasticity of Arabidopsis thaliana in different growth regimes. Plants were grown in climate chambers under high light (600 μmol quanta m^-2 s^-1) with 9 h (SD) or 16 hour (LD) photoperiods and under field conditions.

Figure 10

Variation in non-photochemical quenching (NPQ) in natural Arabidopsis accessions, a PsbS mutant (npq4) and a PsbS overexpresser (oePsbS). A In the field and B in a growth chamber. C Correlation (scatter plot) between NPQ levels for the accessions grown in growth chambers and in the field. Data represent means ± SE for leaves from at least six plants grown in two batches.