Overwintering Periwinkle ( Vinca minor L.) Exhibits Increased Photosystem I Activity

Thylakoid membranes isolated from cold tolerant, herbaceous monocots and dicots grown at 50C exhibit a 1.5-fold to 2.7-fold increase in light saturated rates of photosystem I (PSI) electron transport compared to thylakoids isolated from the same plant species grown at 200C. This was observed only when either water or reduced dichlorophenolindophenol was used as an electron donor. The apparent quantum yield for PSI electron transport was not affected by growth temperature. The higher light saturated rates of PSI electron transport in 50C thylakoids had an absolute requirement for the presence of Na+ and Mg2. The accessibility of reduced dichlorophenolindophenol to the donor site was not affected by growth temperature since 50C and 20°C thylakoids exhibited no significant difference in the concentration of this electron donor required for half-maximal PSI activity. The cation dependent higher rates of light saturated PSI activity were also observed when rye thylakoids were developed under intermittent light conditions at 50C. Thus, this cation effect on PSI activity appeared to be independent of light harvesting complex I and 11. The extent of the in vitro reversibility of this cation effect appeared to be limited by an inherent decay process for PSI electron transport. The rate of decay for PSI activity was greatest when thylakoids were isolated in the absence of NaCI and MgCI2.We conclude that exposure of plants to low growth temperatures induces a reorganization of thylakoid membranes which increases the light saturated rates of PSI electron transport with no change in the apparent quantum efficiency for this reaction. Cations are required to stabilize this reorganization.

supporting

confidence: 57%

“…However, this cation dependence is not mediated by LHCII or LHCI. 10 mM NaCl, and 5 mM MgCl2. In experiments where thylakoids were isolated in the absence of cations, NaCl and MgCl2 were omitted from all of the above buffers.…”

mentioning

confidence: 99%

Low Growth Temperature-Induced Increase in Light Saturated Photosystem I Electron Transport Is Cation Dependent

Hüner¹,

Reynolds²

1989

“…Growth temperature regimen was 20/160C (day/night) for all plant species except spinach, which was 16/160C (day/night), and maize, which was 25/250C (day/ night). Periwinkle (Vinca minor L.) leaves were harvested from plants grown outdoors under natural summer conditions (13).…”

mentioning

confidence: 99%

Differential Detergent Stability of the Major Light-Harvesting Complex II in Thylakoids Isolated from Monocotyledonous and Dicotyledonous Plants

Hüner

Campbell²,

Król³

et al. 1992

A survey of isolated thylakoids from 11 different higher plant species (Spinacia oleracea L., Pisum sativum L., Vicia faba L., Brassica napus L., Vigna sinensis L., Vinca minor L., Secale cereale L., Triticum aestivum L., Triticosecale Wittn., Hordeum vulgare L., Zea mays L.) indicated that the ratio of the oligomeric:monomeric form of the light-harvesting complex 11 was twofold higher for the dicots (3.16 ± 0.35) than the monocots (1.64 ± 0.25) examined under identical separation procedures. Under conditions specifically designed to stabilize the oligomeric form in vitro, we show that the oligomeric form of dicot light-harvesting complex 11 is twice as stable to solubilization in the presence of sodium dodecyl sulfate (SDS) than that observed for monocots. This decreased stability of monocot light-harvesting complex 11 is associated with a twofold increase in the trienoic fatty acid level of thylakoid phosphatidylglycerol but with no significant changes in the trienoic fatty acid levels in the major galactolipids. In addition, SDS polyacrylamide gel electrophoresis and western blot analyses with monoclonal antibodies indicated that monocots exhibited greater heterogeneity in the polypeptide complements associated with subtractions of light-harvesting complex 11 than the dicots examined. The data indicate that the oligomeric form of the lightharvesting complex 11 is not the result of a simple oligomerization of a common monomeric unit. We suggest that the difference in stability of the oligomeric form of light-harvesting complex 11 in isolated thylakoids of monocots and dicots is probably due to a differential accessibility to SDS. The differential SDS accessibility may be due to differences in thylakoid protein-protein and/or protein-lipid interactions.The major Chl a/b LHCII2 was one of the first pigment proteins to be characterized in higher plants (6,26,27 Approximately 50% of Chl and about 30% of the protein present in higher plant thylakoids is associated with LHCII (25, 26). The remainder of the Chl is associated with LHCI, core antennae, and reaction center complexes of PSII and PSI (10, 22). The oligomeric form (LHCIIb) of LHCII, with an apparent molecular mass of 72 kD and a Chl a/b of 1.0 to 1.3, is considered to be the primary form of this complex. Upon denaturation of the holocomplex with SDS, typically three to four polypeptides are observed in the molecular mass range of 25 to 30 kD. These polypeptides are the products of a family of light-regulated, nuclear-encoded cab genes (6, 11).Although the in situ form of LHCIIb is not known for certain, recent crystallographic (17, 18) and biochemical data indicate that LHCIIb most likely exists as a trimeric structure. Freeze-fracture data for thylakoid membranes indicate that the 80A particle identified as LHCIIb may be a higher oligomer than the proposed trimer (25). Kuhlbrandt and Wang (18) have shown by electron crystallography at 6A resolution that three membrane-spanning a helices (A, B, and C) exist within the LHCIIb trimer to which 15 Chl...

“…Thylakoids isolated from other cold tolerant, herbaceous plant species such as wheat, spinach, pea, broadbean, and mustard grown at low temperature also exhibit higher light saturated PSI activity (8). In addition, the cold tolerant, herbaceous evergreen, periwinkle, exhibits higher light saturated rates of PSI activity when exposed to natural cold hardening conditions (7).…”

mentioning

confidence: 99%

Effect of Preincubation Temperature on in Vitro Light Saturated Photosystem I Activity in Thylakoids Isolated from Cold Hardened and Nonhardened Rye

Reynolds¹,

Hüner²

1990

light saturated rates of PSI activity even though PSI activity could be detected after 24 cycles. In contrast to thylakoids from 20°C grown rye, thylakoids isolated from 50C grown rye in the presence of Na+/Mg2+ exhibited no increase in light saturated PSI activity after preincubation at any temperature between 0 and 600C. This was not due to damage to PSI electron transport in thylakoids isolated from 50C grown plants since light saturated PSI activity was 60% higher in 50C thylakoids than 200C thylakoids prior to in vitro dark preincubation. However, a two-fold increase in light saturated PSI activity of 50C thylakoids could be observed after dark preincubation only when 50C thylakoids were initially isolated in the absence of Na+/Mg2+. We suggest that 50C rye thylakoids, isolated in the presence of these cations, exhibit light saturated PSI electron transport which may be closer to the maximum rate attainable in vitro than 200C thylakoids and hence cannot be increased further by dark preincubation.