Influence of Age and Illumination on Distribution of Several Calvin Cycle Enzymes in Greening Barley Leaves

Abstract

Activities of phosphoriboisomerase, phosphoribulokinase, and ribulose 1,5-diphosphate carboxylase, protein content, and chlorophyll accumulation in dark-grown barley seedlings were measured before and after illumination. Enzymatic activities, levels of soluble protein, and accumulation (upon illumination) of chlorophyll in leaves declined from tips toward the base. In response to increasing time of illumination, chlorophyll accumulation and activities of phosphoribulokinase and ribulose 1 ,5-diphosphate carboxylase (enzymes located in chloroplasts) increased most in tip portions whereas activity of phosphoriboisomerase and levels of soluble protein (constituents not confined to chloroplasts) increased similarly in all sections of the leaf. Maximum activity of phosphoribulokinase and maximum accumulation of chlorophyll shifted toward median portions of the leaf blade with increased age of seedling before illumination. Maximum activity of ribulose 1 ,5-diphosphate carboxylase and maximum level of soluble protein occurred in all leaf sections when the seedlings were 7 days of age before illumination.Upon the illumination of dark-grown seedlings, chlorophyll accumulates, protein is synthesized, chloroplasts develop an ordered lamellar form, the activity of photosynthetic enzymes increases, and net incorporation of CO2 begins. Some information is available on the development of several of these and other components with position in the leaf and age of the leaf. Rhodes and Yemm (13) reported that chloroplasts were larger and developed faster in the older cells of barley leaf tips than in younger cells at the base. Protochlorophyll levels in etiolated barley leaves declined from the tip toward the base (17). A decline in the tip with increasing age, however, shifted the maximal concentration toward the median sections. Williams and Rijven (19) noted marked differences in the timing of maximum protein and RNA levels for different parts of developing wheat leaves. Information is lacking on the development of photosynthetic enzymes in relation to position in the leaf and the development of other constituents. This paper reports the influence of illumination and leaf age and section on the activities of phosphoriboisomerase, phosphoribulokinase, and ribulose-1,5-diP carboxylase, and on soluble protein and chlorophyll.'Present address:

The development of the activity of the chloroplastic and cytosolic isoenzymes of phosphoglycerate kinase during barley leaf ontogenesis

“…Thereafter the protein remains constant, presumably as the chloroplast development has been completed. Obendorf and Huffaker (1970) have suggested that this phenomenon may be related not only to the manner in which monocotyledonous plants develop, but also to the availibility of substrates during development. They pointed out that availibility of an energy source for a longer time could allow greater physiological development in leaf tips than in the basal sections.…”

“…They pointed out that availibility of an energy source for a longer time could allow greater physiological development in leaf tips than in the basal sections. The basal section of barley appears to contain appreciable amounts of not only chloroplastic PGK, but also LHCP and Rubisco (Obendorf and Huffaker 1970;Viro and Kloppstech 1980), even though there is no photosynthetic CO2 fixation (Baker and Leech 1977). It is not clear if Rubisco is active in this region or whether the oxygenase activity appears first.…”

Suppression of the Barleyuroporphyrinogen III synthaseGene by aDsActivation Tagging Element Generates Developmental Photosensitivity

“…However, when barley seedlings are grown in the dark for >5 d, chlorophyll accumulation upon light exposure rapidly decreases with increasing pregrowth in the dark (Obendorf and Huffaker, 1970). A reversal of the basipedal gradient of chlorophyll accumulation is also observed in these seedlings, suggesting that the more mature tissues of these leaves are beginning to undergo programmed senescence (Obendorf and Huffaker, 1970).…”

“…Transfer of these seedlings to the light causes a rapid synthesis of chlorophyll and plastid maturation that again follows a basipedal gradient, such that within 48 h these seedlings contain chlorophyll amounts similar to light-grown plants (Robertson and Laetsch, 1974). However, when barley seedlings are grown in the dark for >5 d, chlorophyll accumulation upon light exposure rapidly decreases with increasing pregrowth in the dark (Obendorf and Huffaker, 1970). A reversal of the basipedal gradient of chlorophyll accumulation is also observed in these seedlings, suggesting that the more mature tissues of these leaves are beginning to undergo programmed senescence (Obendorf and Huffaker, 1970).…”

“…Prolonged growth (>5 d) of barley seedlings in the dark greatly reduces their ability to accumulate chlorophyll upon subsequent light exposure (Obendorf and Huffaker, 1970). Chlorophyll content was determined for wild-type seedlings grown under either constant glasshouse conditions or in the dark followed by transfer to glasshouse light when the second leaf was almost fully expanded ( Figure 5B).…”