Different pigment and antioxidant profiles in field-collected and
lab-cultured plants
Comparison of the photosynthetic pigment profiles in field-collected and
lab-cultured S. caninervis supports this hypothesis of relaxation
of sustained NPQ. Zeaxanthin, which is associated with both rapidly
reversible (qE) and sustained NPQ mechanisms such as photoinhibitory
quenching (qI; Demmig-Adams, 1990; Verhoeven et al. , 1996), was
more than five times higher in field-collected plants than in
lab-cultured plants (Table 3). In fact, the relative VAZ pool was larger
in field-collected plants, which is unsurprising as these pigments
increase in abundance in high-light environments (Siefermann-Harms 1985;
Demmig-Adams 1990; Jahns, Latowski & Strzalka 2009). Similarly, the
total chlorophyll pool was reduced and the ratio of chlorophylla :b was increased in field-collected plants, also
consistent with acclimation to high light intensity (Björkman 1981;
Leong & Anderson 1984; Lindahl, Yang & Andersson 1995). Tocopherol
abundance was much higher in field-collected plants than those cultured
in the lab, as well (Table 5). Tocopherols are membrane-bound
antioxidants that may be increased due to the higher light intensity and
UV exposure in the field site (Delong & Steffen 1998; Yao et al.2015) or due to other stresses such as desiccation and freezing that
these plants frequently face in their natural habitat (Munné-Bosch
2005).