Development of photosystems 2 and 1 during leaf growth in grapevine seedlings probed by chlorophyll a fluorescence transient and 820 nm transmission in vivo

Abstract

Chlorophyll (Chl) a fluorescence transient and 820-nm transmission kinetic were investigated to explore the development of photosynthetic apparatus in grapevine leaves from emergence to full expansion. In this study, all leaves at various developing stages exhibited typical Chl a fluorescence transient. In newly initiating leaves, the maximum quantum yield of primary photochemistry (φ P0 ) was slightly lower (<10 %) than that in fully expanded leaves. Nevertheless, the fluorescence rise from O to J step was clearly speeded up in young leaves compared with that in fully expanded leaves. Additionally, a distinct K step appeared in young leaves at high irradiances. With leaf development, the efficiency that a trapped exciton can move an electron into the electron transport chain further than Q A -(Ψ 0 ), the quantum yield of electron transport beyond Q A (φ E0 ),   electron transport flux per excited cross section (ET 0 /CS 0 ), the amount of active photosystem (PS) 2 reaction centres per excited cross section (RC/CS 0 ), and the performance index on cross section basis (PI CS ) increased gradually and rapidly. Young leaves had strikingly lower amplitude of transmission at 820 nm. A linear relationship between Ψ 0 and the transmission at 820 nm (I 30 /I 0 ) was evident. Based on these data, we suggest that (1) the primary photochemistry of PS2 may be not the limiting step of the photosynthetic capacity during leaf growth under natural irradiance; (2) oxygen evolving complex (OEC) might be not fully connected to PS2 at the beginning of leaf growth; (3) though there are a few functional PS1 and PS2 at the early stages of leaf development, they match perfectly.

Performance index as a sensitive indicator of water stress in Triticum aestivum L.

“…Performance index PI abs is found to be a very sensitive parameter in different crops and in most of environmental stress situations (Strasser et al 2000, Jiang et al 2006, Christen et al 2007, Oukarroum et al 2007, which is in accordance with our results achieved on winter wheat plants under drought stress. Van Heerden et al (2007) observed also a very good positive correlation between CO 2 assimilation capacity and PI abs values under water stress.…”

Photosynthetic characterization of Jerusalem artichoke during leaf expansion

“…In contrast to PSII, less attention was paid to PSI activity during leaf growth. Only a few functional PSIs were observed to be developed at the initial stages of leaf growth in grapevine, but it matched perfectly with PSII (Jiang et al 2006c). It should be noticed that young leaves are more susceptible to photodamage, since excited energy captured by light harvesting complexes is less spent on promoting the carbon assimilation.…”

“…J-step appears because accumulation of Q A -reaches the maximal level, and Vj can be used to reflect the change of J-step (Strasser et al 2004). Jiang et al (2006c) detected a higher K-step in young leaves of grapevine, and it was explained that the functional connection between OEC and PSII was not fully built at the beginning of leaf growth. However, Vk was not higher in NIL than that in NEL or EL (Fig.…”

“…Thus, we suppose that leaf area expansion process also involved the synthesis and assembly of photosynthetic apparatus in Jerusalem artichoke. So far, it is not definite whether primary photochemical reaction of PSII is the limiting step of photosynthetic capacity during the leaf growth, as contradictory results have been reported in different plants (Lebkuecher et al 1999;Srivastava et al 1999;Choinski et al 2003;Jiang et al 2005Jiang et al , 2006c. These contradictory results can be attributed to the inconsistent culture protocol or plant species.…”

“…It was observed that wPo increased along with leaf growth (Choinski et al 2003). However, Jiang et al (2006c) suggested that primary photochemical reaction of PSII was almost built up at the early beginning of leaf development in grapevine, and they also inferred that oxygen evolving complex might be not perfectly connected to PSII in young leaves. In addition, electron transport in acceptor side of PSII was also proved to be less efficient in young leaves of elm seedlings (Jiang et al 2006a, b).…”