Leaf chlorophyll, net gas exchange and chloroplast ultrastructure in citrus leaves of different nitrogen status

Abstract

One-year-old 'Cleopatra mandarin' (Citrus reticulata Blanco) seedlings were raised in a greenhouse and fertilized with nitrogen (N) at four application frequencies. Nitrogen-deficient leaves (86 mmol N m-2) had less chlorophyll per unit area, but a greater chlorophyll a:b ratio than N-fertilized leaves (> 187 mmol N m-2). Leaf dry mass per area (DM area-1) and total chlorophyll concentration increased linearly with increasing leaf N, whereas chlorophyll a:b ratio declined. Net assimilation of CO2 (A(CO2)) and leaf water-use efficiency (WUE) reached maximum values in leaves with approximately 187 mmol N m-2. Nitrogen-deficient leaves exhibited small chloroplasts with no starch granules; grana and stroma lamellae that coincided with the accretion of numerous large plastoglobuli in the stroma disintegrated. High-N leaves had large chloroplasts with well-developed grana, stroma lamellae and starch granules that enlarged with increasing N concentration. The lack of an increase in A(CO2) capacity at leaf N concentrations above 187 mmol N m-2 appeared to be correlated with the presence of numerous large starch granules.

Tocopherol Cyclase (VTE1) Localization and Vitamin E Accumulation in Chloroplast Plastoglobule Lipoprotein Particles

“…Under high light stress conditions, levels of tocopherols increase (72), and VTE1 is up-regulated (45). The presence of VTE1 and tocopherols (this paper) together with the reported increase in size and number of plastoglobules (33)(34)(35) provides a molecular explanation for the role of plastoglobules under conditions resulting in oxidative stress.…”

“…At least two PAP/fibrillins were localized at the periphery of plastoglobules (3,26), and purified fibrillin was able to promote carotenoid fibril assembly in vitro (1), suggesting a structural function (29). Upregulation of several PAP/fibrillins has been correlated with various treatments generating reactive oxygen species (20, 24, 30 -32), and enlarged plastoglobules have been described in chloroplasts under abiotic stress such as drought (33), nitrogen starvation (34), or hypersalinity (35). Taken together, these observations implicate plastoglobules in stress tolerance.…”

Dual targeting of a mature plastoglobulin/fibrillin fusion protein to chloroplast plastoglobules and thylakoids in transplastomic tobacco plants

“…The mechanisms and significance of variations of plastoglobule size and number are not completely understood. The enlargement of plastoglobules has been described in chloroplasts under abiotic stress, such as drought (Eymery and Rey 1999) and nitrogen starvation (Bondada and Syvertsen 2003). In the case of nitrogen starvation this observation was attributed to chlorophyll degradation and concomitant accumulation of phytylesters in plastoglobules (Gaude et al 2007).…”

Non-destructive estimation of chlorophyll and nitrogen content in leaf ofRosa damascena(Mill)

“…In our case, more than 80% of the variation in N was predicted by the CCM-200 reading, probably due to the fact that more N is bound up in Chl and other photosynthetic compounds than in the soluble protein pool in the Damask rose leaf. The uneven distribution of N between soluble proteins and the light-harvesting complex can be intensified by leaf age, growth environment, or cultural practices (Bondada and Syvertsen 2003).…”