Effect ofGlomus aggregatumon photosynthetic function of snap bean in response to elevated ozone

Abstract

Snap bean genotypes (Phaseolus vulgaris L.) with different ozone (O 3 ) sensitivities (line S156: O 3 -sensitive; line R123: O 3 -tolerant) were grown for 70 days with or without inoculation of arbuscular mycorrhizal (AM) fungi under ambient (C AMB = 20 nanolitres (nl)/l and elevated (C MID = '50 nl/l and C HIG = 80 nl/l) O 3 . Sequential determinations (leaf injury, pigment concentration, chlorophyll fluorescence, photosynthesis, etc) were carried out during plant growth to evaluate mycorrhizal influence on the photosynthetic function of the two genotypes under elevated O 3 . Inoculation with AM fungi alleviated leaf injury in both genotypes and delayed time of injury manifestation (TIM) in the R123 line at the blooming stage (growth stage (GS): 61-65 (Zadoks scale, Zadoks et al. 1974), 30-35 days after the onset of O 3 fumigation), but mycorrhizal effect was slight at the initial growth stage (GS 11-13, 0-5 days after onset of O 3 fumigation). Relative to the non-mycorrhizal plant, AM fungi inoculation increased the concentrations of chlorophyll (Chl) a, Chl b and carotenoids in S156 plants, regardless of O 3 levels, while in R123 plants a similar effect was observed only in the C AMB treatment. At the blooming (GS 61-65) and the pod filling (GS 71-77, 45-50 days after starting O 3 fumigation) stages, photosynthetic rate, stomatal conductance and transpiration rate for the two genotypes decreased with elevated O 3 in all treatments, although the effect was reduced in C AMB and C MID treatments in AM-inoculated plants; however, the mycorrhizal effect was slight in the C HIG treatment. Intercellular carbon dioxide concentration increased with elevated O 3 regardless of AM fungi inoculation, but it was lower in the mycorrhizal plants than in the non-mycorrhizal plants, in most cases. Furthermore, AM fungi inoculation significantly increased the maximum quantum yield of photosystem II (PS II) photochemistry (Fv/Fm) and electron transport rate in both genotypes in the C HIG treatment. The present study indicated that in some cases, AM fungi inoculation can enhance plant tolerance to elevated O 3 through improving plant photosynthetic function, but the effect was reduced by serious O 3 stress.

Pollution resistance assessment of existing landscape plants on Beijing streets based on air pollution tolerance index method

“…The mean O 3 concentrations at the three sampling sites were in the order of 130 mg/m 3 (MLP) o 145 mg/m 3 (YGZ) o147 mg/m 3 (BZF), which was negatively related with the mean leaf TCH. It was reported that O 3 would reduce the effect of photosynthetic function in plants (Wang et al, 2015), and stomatal movements regulate gas exchange; which directly affect the efficiency of photosynthesis and the sensitivity of plants to air pollutants such as ozone (Nagatoshi et al, 2016). Our results indicate that the TCH value in plant leaves decreased with higher concentration of SO 2 and O 3 , which is in agreement with previous studies Wei et al, 2014 ).…”

Protecting the photosynthetic performance of snap bean under free air ozone exposure

“…In this study, plants sprayed with distilled water had higher F o and lower F v /F m under 2 × ambient O 3 compared with ambient air, which indicated that photoinhibition and photoinactivation of photosystem II complexes occurred (Bradbury and Baker, 1986;Leipner et al, 2001;Thwe et al, 2014). This result is in accordance with other studies of O 3 effects on snap bean (Flowers et al, 2007;Wang et al, 2015). The stable F o and F v /F m in plants sprayed with EDU or KIN between different O 3 concentrations suggested that the EDU or KIN spraying protected photosystem II complexes and avoided the occurrence of photoinhibition.…”

Mycorrhizal Stimulation of Leaf Gas Exchange in Relation to Root Colonization, Shoot Size, Leaf Phosphorus and Nitrogen: A Quantitative Analysis of the Literature Using Meta-Regression

“…This symbiont combination also led to increased gas exchange relative to non-AM plants with exposure to low temperature stress ( Zhu et al, 2010 ). AM symbiosis has also helped bolster CER, g s , and E with exposure to ozone stress, in Phaseolus vulgaris colonized by Glomus aggregatum ( Wang et al, 2015 ). AM symbiosis has resulted in higher gas exchange rates when plants were faced with heavy metal stress, e.g., chromium by Helianthus annuum colonized by G. intraradices ( Davies et al, 2002 ) and Ampelopteris prolifera colonized by Glomus deserticola ( Singh et al, 2014 ).…”