Photosynthetic characteristics of diploid honeysuckle (Lonicera japonica Thunb.) and its autotetraploid cultivar subjected to elevated ozone exposure

Abstract

In order to investigate the effect of chromosome doubling on ozone tolerance, we compared the physiological responses of a diploid honeysuckle (Lonicera japonica Thunb.) and its autotetraploid cultivar to elevated ozone (O 3 ) exposure (70 ng g -1 , 7 h d -1 for 31 d). Net photosynthetic rate (P N ) of both cultivars were drastically (P<0.01) impaired by O 3 . Although there were significantly positive correlation between P N and stomatal conductance (g s ) in both cultivars under each treatment, the decreased g s in O 3 might be the result rather than the cause of decreased P N as indicated by stable or increasing the ratio of intercellular to ambient CO 2 concentration(C i /C a ). P N under saturating CO 2 concentration (P Nsat ) and carboxylation efficiency (CE) significantly decreased under O 3 fumigation, which indicated the Calvin cycle was impaired. O 3 also inhibited the maximum efficiency of photosystem II (PSII) photochemistry in the dark-adapted state (F v /F m ), actual quantum yield of PSII photochemistry (Φ PSII ), electron transport rate (ETR), photochemical quenching coefficient (q P ), non-photochemical quenching (NPQ), the maximum in vivo rate of Rubisco carboxylation (V cmax ) and the maximal photosynthetic electron transport rate (J max ) which demonstrated that the decrease in P N of the honeysuckle exposed to elevated O 3 was probably not only due to impairment of Calvin cycle but also with respect to the lightharvesting and electron transport processes. Compared to the diploid, the tetraploid had higher relative loss in transpiration rate (E), (g s ), (P Nsat ), V cmax and J max . This result indicated that the Calvin cycle and electron transport in tetraploid was damaged more seriously than in diploid. A barely nonsignificant (P=0.086) interaction between O 3 and cultivar on P N suggested a higher photosynthetic sensitivity of the tetraploid cultivar.

Ozone exposure causes a decoupling of conductance and photosynthesis: implications for the Ball-Berry stomatal conductance model

“…The reductions in photosynthesis are typically driven by both a reduction in leaf chlorophyll content (Heagle et al 1996;Sharma et al 2003) and the quantity and activity of the primary carboxylation enzyme Rubisco (Fiscus et al 2005;Ojanpera et al 1998). Further, whole-plant fumigation experiments suggest that decreases in photosynthesis can be independent of stomatal conductance (Francini et al 2007;Noormets et al 2001;Zhang et al 2010), suggesting that decreases in carboxylation, rather than conductance, are responsible for decreases in light-saturated photosynthesis.…”

Influences of Saccharomyces cerevisiae on gas exchange and water-use efficiency in Vicia faba L.

“…CE indicates carbon assimilation (Ding et al, 2014), and its decrease under yeast treatment was probably due to the reduction in activity and/or quantity of Rubisco (Zhang et al, 2010). P n decreased after 6 days of yeast treatment, while CE showed no decrease, indicating that yeast did not impair mesophyll processes (Zhang et al, 2010). Therefore, the decrease in P n was caused by stomatal factors under yeast treatment.…”

Physiological and fitness differences between cytotypes vary with stress in a grassland perennial herb

“…Differences in the efficiency of photosynthetic electron transport between diploid and tetraploid plants grown in non-stressed conditions documented in the literature are usually small and non-significant (e.g. [ 20 , 37 , 38 , 40 , 81 ]. However, Majdi et al [ 76 ] demonstrated significantly lower values of maximum photochemical efficiency of photosystem II in tetraploid Tanacetum parthenium compared to diploid individuals.…”