Inhibition of photosynthesis and export in geranium grown at two CO₂ levels and infected with Xanthomonas campestris pv. Pelargonii

Abstract

The effects of CO 2 enrichment on growth of Xanthomonas campestris pv. pelargonii and the impact of infection on the photosynthesis and export of attached, intact, 'source' leaves of geranium (Pelargonium x domesticum, 'Scarlet Orbit Improved') are reported. Two experiments were performed, one with plants without flower buds, and another with plants which were flowering. Measurements were made on healthy and diseased leaves at the CO 2 levels (35 Pa or 90 Pa) at which the plants were grown. There were no losses of chlorophyll, or any signs of visible chlorosis or necrosis due to infection. Lower numbers of bacteria were found in leaves at high CO 2 , suggesting growth at elevated CO 2 created a less favourable condition in the leaf for bacterial growth. Although high CO 2 lowered the bacterial number in infected leaves, reductions in photosynthesis and export were greater than at ambient CO 2 . The capacity of infected source leaves to export photoassimilates at rates observed in the controls was reduced in both light and darkness. In summary, the severity of infection on source leaf function by the bacteria was increased, rather than reduced by CO 2 enrichment, underscoring the need for further assessment of plant diseases and bacterial virulence in plants growing under varying CO 2 levels.

Daily photosynthetic and C‐export patterns in winter wheat leaves during cold stress and acclimation

“…4A). These data support many other studies showing that the majority of C is translocated during the day concurrently with photosynthesis rather than during the night (Fondy and Geiger 1982, Gordon 1986, Kalt‐Torres et al 1987, Jiao and Grodzinski 1998, Grimmer and Komor 1999, Jiao et al 1999).…”

Photosynthesis, immediate export and carbon partitioning in source leaves of C3, C3‐C4 intermediate, and C4Panicum and Flaveria species at ambient and elevated CO2 levels

“…The preferential pattern of sugar accumulation noted at high CO 2 with the Panicum C 4 types was not observed in maize and sorghum even though C 4 monocots and other Gramineae species tended to accumulate more sugars than starch in their leaves ( Gordon 1986; Grodzinski et al 1998 ). Long‐term CO 2 exposures are required to assess plant acclimation to CO 2 enrichment and the changes in immediate and total export from source leaves ( Grimmer & Komor 1999; Jiao, Goodwin & Grodzinski 1999).…”

Relationship Between Insect Damage and Chlorophyll Content in Mediterranean Oak Species

“…In literature, information is available regarding the effect of biotic agents such as herbivorous insect (Romanyk and Cadahia, 1992), other arthropods (Longonje et al, 2014), and pathogens on plants or on their photosynthesis rate (Osmond et al, 1990;Faeth, 1992;Jiao et al, 1999) 2006) stated that arthropods and pathogens damaging leaves in natural ecosystems may reduce photosynthesis rather than directly injured plant tissue, since foliar damage often triggers complex interactions between defensive processes and photosynthesis. Herbivory damage can alter plant physiology by inducing the production of costly defensive compounds or disrupting water and nutrient movements.…”