Inhibition of photosynthesis by viral infection: Effect on PSII structure and function

Abstract

The effect of viral infection on photosynthesis was investigated infected plants. The CP accumulation level was dependent upon both the post-infection time and the virus analyzed, but in Nicotiana benthamiana Gray plants infected with different strains of pepper and paprika mild mottle viruses (PMMoV independent of the CP itself since hybrid viruses did not behave as their parental viruses with the same CP, with and PaMMoV) and chimeric viral genomes derived from them. In both symptomatic and asymptomatic leaves of virus-respect to PSII inhibition, CP accumulation rates and OEC infected plants, photosynthetic electron transport in photosys-protein levels. Modulated chlorophyll (Chl) fluorescence and tem II (PSII) was reduced. In all cases analyzed, viraloxygen evolution measurements carried out in both types of infection affected the polypeptide pattern of the oxygen-evolv-leaves showed that the quantum yield of PSII electron transport was diminished in infected plants with respect to those of ing complex (OEC) in thylakoid membranes. The levels of control plants. The decrease in electron transport efficiency both the 24 and 16 kDa proteins were reduced to a differing extent when compared with the levels in healthy control. This was mainly caused by a reduction in the fraction of open loss of the OEC extrinsic proteins affected the oxygen evolu-reaction centers. The infected plants also showed a reduction tion rates of thylakoid membranes and leaves from infected in the efficiency of excitation capture in PSII by photoprotecplants. Additionally, viral coat protein (CP) was found associ-tive thermal dissipation of excess excitation energy. ated with the chloroplasts and the thylakoid membranes of the phenomenon under biotic stress, as is also observed under abiotic stress conditions. However, the mechanism of action of the viral infection upon PSII remains unclear (see Balachandran et al. 1997).Chlorophyll (Chl) fluorescence measurements show that the PSII photochemical efficiency was decreased by the viral infection (Hodgson et al. 1989, van Kooten et al. 1990, Balachandran and Osmond 1994, Balachandran et al. 1994a). Studies of imaging PSII fluorescence quenching (Balachandran et al. 1994b) also demonstrated that in the youngest, most susceptible leaves of tobacco plants systemically infected with tobbaco mosaic virus (TMV), distur-

Herbicide-Affected Plant Metabolism Reduces Virus Propagation

“…Compared to reports publishing structural and functional defects on PSII under viral infection (Almá si et al, 2000;Rahoutei et al, 2000;Funayama-Noguchi, 2001;Pé rez-Bueno et al, 2004), however, these changes were the opposite. PSII activity somewhat increased as it was evidenced from the tendency of changes in fluorescence induction parameters (increasing ΔF/F m ', F v /F m , F v '/F m ', decreasing NPQ).…”

“…Most frequently occurring symptoms, like chlorosis, mosaic, and dwarfing, suggest that viruses can influence photosynthetic processes of host plants. Virus infection was shown to change the structure of the photosynthetic apparatus, the activity of electron transport, photosynthetic enzymes, and other processes, which are in close relation to photosynthesis (Goodman et al, 1986;Rahoutei et al, 2000;Almá si et al, 2000Almá si et al, , 2001Funayama-Noguchi, 2001;Harsá nyi et al, 2002;Pé rez-Bueno et al, 2004).…”

Inducible expression of magnesium protoporphyrin chelatase subunit I (CHLI)-amiRNA provides insights into cucumber mosaic virus Y satellite RNA-induced chlorosis symptoms

“…The disturbance of chloroplast functions may be responsible for the production of chlorosis that is associated with virus infection [19]. Several plant-virus interaction studies have revealed that virus infection inhibits host photosynthesis, which is usually accompanied by viral symptoms [7,9,10,16,29]. Virus infection commonly causes chlorosis resulting into impaired chlorophyll biosynthesis and reduced photosynthetic activities that lead to a decrease in biomass production and significant loss in crop yield [44].…”

Comparison of a compatible and an incompatible pepper-tobamovirus interaction by biochemical and non-invasive techniques: Chlorophyll a fluorescence, isothermal calorimetry and FT-Raman spectroscopy

“…The oxygen-evolving complex (OEC) of PSII was shown to be one of the main targets of PMMoV infection in thylakoid membranes of Nicotiana benthamiana leaves. The infected plants also showed a reduction in the efficiency of excitation capture in PSII by photoprotective thermal dissipation (Rahoutei et al, 2000). In recent years non-invasive chlorophyll fluorescence imaging techniques have been developed to continuously follow-up the physiological status and performance of plants, as well as to detect stress-induced deviations presymptomatically (Chaerle et al, 2007;Rolfe and Scholes, 2010).…”

“…The level of carotenoids, which also have a role in light harvesting and in protection from excess light by energy dissipation and singlet oxygen deactivation, can also be decreased by virus infections (Wilhelmov a et al, 2005). The photosynthetic electron transport in photosystem II (PSII) is usually severely impaired in virus-infected leaves, which results in disturbed CO 2 fixation, reduced carbohydrate accumulation, and plant growth (Rahoutei et al, 2000;Alm asi et al, 2001). On the other hand, the marked accumulation of starch in the chloroplasts was also reported in virus infected susceptible leaves, which suggests that the sink-source relationships should also be considered (T ecsi et al, 1994).…”