Photosynthetic changes that occur during aging of cypress (Cupressus sempervirens L.) needles

Abstract

2-years-old cypress needles (A2) were physiologically most active with regard to net photosynthetic (P N ) and electron transport rates. Variable to maximum fluorescence (F v /F m ) ratios of dark-adapted needles were higher in A2 needles than in current year (A1) or senescent (A4) needles. Lower F v /F m values in these stages seemed to be caused not by photoinhibition but by a low photochemical capacity as suggested from the chlorophyll (Chl) a/b ratios. In isolated thylakoids, lower rates of whole chain and photosystem 2 (PS2) activities were observed in A4 needles, while higher rates were observed in A2 needles. A similar trend was noticed for contents of ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBPC) and total soluble proteins. The artificial exogenous electron donor Mn 2+ failed to restore the loss of PS2 activity in 3-year-old (A3) and A4 needles, while diphenylcarbazide and NH 2 OH significantly restored the loss of PS2 activity. The marked loss of PS2 activity in A4 needles was primarily the result of the loss of 33, 28-25, 23, and 17 kDa polypeptides. A marked loss of RuBPC activity in A4 needles is mainly due to the loss of 15 (SSU) and 55 (LSU) kDa polypeptides.Additional key words: chlorophyll fluorescence; diphenylcarbazide; donor side; electron transport; photosystems 1 and 2; polyacrylamide gel electrophoresis; polypeptides; ribulose-1,5-bisphosphate carboxylase/oxygenase.

Seasonal fluctuations of photosynthetic pigments content in Taxus baccata needles

“…In turn, decreasing Chl a/b ratio in progressively older T. baccata needles is similar to changes observed in Cupressus sempervirens aging needles (La Porta et al, 2006). In case of Cupressus sempervirens, authors explained the changes by decreasing amount of Chl a resulting from aging processes of needles.…”

“…As for yews, the life span of needles is dependent on the environmental conditions, from 4 to 8 years . The progressive aging of the needles eventually leads to an imbalance between biosynthesis and degradation of chlorophyll and may be observed, among others, through changes in the concentrations of pigments and their degradation products (Kutík, 1998;La Porta et al, 2006). The amount of photosynthetic pigments in trees is subjected to changes during growth and development; it also depends, among others, on their age, position around the crown, light conditions, and access to minerals and water (Merzlyak et al, 1999;Silkina & Vinokurova, 2009;Sarala & Saravana, 2011).…”

Factors controlling soil organic carbon sequestration under exotic tree plantations: A case study using the CO2Fix model in southwestern Ethiopia

“…The model estimates the litter production by multiplying each of the biomass components by a specific turnover coefficient. The turnover coefficient of Cupressus needles (Table 3) was approximated from Porta et al (2006) and that of Pinus approximated to that of Pinus radiata (Ewers and Schmid, 1981). The turnover coefficient of E. grandis leaves was approximated to that of other Eucalyptus spp.…”

Quantifying the dynamics of light tolerance inArabidopsisplants during ontogenesis

“…; la Porta et al . ; Radochová & Tichá ). There are, however, certain limitations to the understanding of the dynamics of photosynthesis during plant ontogenesis with these techniques.…”