Chloroplast Distribution in Arabidopsis thaliana (L.) Depends on Light Conditions during Growth

Abstract

Chloroplasts of Arabidopsis fhaliana move in response to blue light. Sensitivity to light and the range of fluence rates to which the chloroplasts respond were found to be comparable to those of other higher plants studied. We investigated typical chloroplast distributions in Arabidopsis grown under three different light conditions: standard-light conditions, similar to natural light intensities; weaklight intensities, close to the compensation point of photosynthesis; and strong-light intensities, close to the saturation of the lightresponse curve of photosynthesis. We observed a striking difference in chloroplast arrangement in darkness between plants grown under weak-and strong-light conditions. There was a slight difference after weak-light pretreatment, and the arrangements of chloroplasts after strong-light pretreatment in both plant groups were very similar. These results support the ecological significance of chloroplast movements.Chloroplast movement is a phenomenon commonly observed throughout the plant kingdom (see reviews: Zurzycki, 1980; Haupt and Scheurelein, 1990;Wada et al., 1993). In most plants studied so far, the movement is controlled by a blue UV-absorbing system (Zurzycki, 1980; Galland and Senger, 1980). Only in a few cases are red light and phytochrome also involved: Mougeotia (Haupt, 1959), Adiantum (Yatsuhashi et al., 1985), and Mesotaenium (Haupt and Thiele, 1961). Chloroplast rearrangements in cells are induced and maintained by irradiation and depend on light direction, wavelength, and irradiance.There are two extreme chloroplast positions: (a) face position (low fluence rate arrangement), with chloroplasts at the cell walls perpendicular to light; and (b) profile position (high fluence rate arrangement), with chloroplasts at the walls parallel to light. In D, the chloroplasts are distributed either randomly around a11 of the cell walls, or their position depends on local factors inside the cell (Haupt and Scheuerlein, 1990). These three arrangements are typical of species with multichloroplast cells like Funaria, Lemna, and Tradescantia. There are some differences in chloroplast movement in plants with cells containing one large chloroplast (e.g. Hormidium, Mougeotia, and Mesotaenium) or for coenocytes (eg. Vaucheria) (see review: Schonbohm, 1980). Although movement patterns differ in their detail in various species, the common result of these patterns is greater exposure of chloroplasts to WL and reduced exposure under SL conditions.The conventional interpretation of the ecological role of chloroplast movements is that they result in optimizing light utilization in photosynthesis. However, little is actually known about the significance of chloroplast movements, and only a few studies have been devoted to this problem. Zurzycki (1955) was the first to ask if there was a correlation between the level of photosynthesis and chloroplast response. He carried out experiments on the green alga Mougeotia sp., the moss Funaria hygrometrica, and the duckweed Lemna trisulca, a11 of which hav...

Strictness of the Centrifugal Location of Bundle Sheath Chloroplasts in Different NADP-ME Type C4Grasses

“…IE) and sorghum ( Fig.1H) distributed to the adaxial side facing the light source. Such a light-dependent arrangement of BSC chloroplast is a typical response of mesophyll chloroplasts in C 3 plants (Haupt and Scheuerlein, 1990;Trojan and Gabrys, 1996), and this is the first observation of the phototactic movement in C 4 plants. BSC chloroplasts of Eriachne were randomly oriented in the cells under LL (Fig.…”

Plastid Movement Impaired 2, a New Gene Involved in Normal Blue-Light-Induced Chloroplast Movements in Arabidopsis

“…In Arabidopsis, red light does not initiate chloroplast movement, but it is absorbed efficiently by chlorophyll. As chloroplasts relocate in leaf cells, the amount of red light transmitted through the leaf changes, leading to decreases in light transmittance as chloroplasts accumulate along the periclinal cell walls and increases in transmittance when chloroplasts gather on anticlinal walls (Trojan and Gabrys, 1996;Kagawa and Wada, 2000).…”

“…Light-directed chloroplast movements have been observed throughout the plant kingdom (Zurzycki, 1961;Lechowski, 1974;Haupt and Scheuerlein, 1990;Gorton and Vogelmann, 1996;Trojan and Gabrys, 1996). Under low-intensity light, chloroplasts migrate to periclinal cell walls in what has been termed the low-light or accumulation response.…”

“…In contrast, highintensity light induces movement to anticlinal cell walls in what is referred to as the high-light or avoidance response. Accumulation along the periclinal cell walls under low-light conditions is believed to maximize light capture for photosynthesis, whereas the avoidance response to high light protects chloroplasts from photodamage by positioning chloroplasts in areas where light intensities are lowest (Zurzycki, 1961;Lechowski, 1974;Gorton and Vogelmann, 1996;Park et al, 1996;Trojan and Gabrys, 1996). Indeed, upon transfer to high light, Arabidopsis (Arabidopsis thaliana) mutants that lack light-induced chloroplast movements displayed signs of photodamage more rapidly than wild type (Kasahara et al, 2002).…”

Acquisition of plastid movement responsiveness to light during mesophyll cell differentiation

“…Blue light-induced directional movements of chloroplasts occur in many lower and higher plant species; red light is active only in a limited number of the plant genera investigated so far (Trojan and Gabrys 1996, Augustynowicz and Gabrys 1999, for review see: Wada et al, 2003. Strong light induces chloroplasts to gather at the walls parallel to the light direction (profile position, avoidance response) while weak light directs them to the walls perpendicular to the light direction (face position, accumulation response).…”