Comparative effects of growth irradiance on photosynthesis and leaf anatomy of Flaveria brownii (C4-like), Flaveria linearis (C3?C4) and their F1 hybrid

Abstract

Photosynthetic rates and related anatomical characteristics of leaves developed at three levels of irradiance (1200, 300 and 80 umol · m(-2) · s(-1)) were determined in the C4-like species Flaveria brownii A.M. Powell, the C3-C4-intermediate species F. linearis Lag., and the F1 hybrid between them (F. brownii × F. linearis). In the C3-C4 and F1 plants, increases in photosynthetic capacity per unit leaf area were strongly correlated with changes in mesophyll area per unit leaf area. The C4-like plant F. brownii, however, showed a much lower correlation between photosynthetic capacity and mesophyll area per unit leaf area. Plants of F. brownii developed at high irradiance showed photosynthetic rates per unit of mesophyll cell area 50% higher than those plants developed at medium irradiance. These results along with an increase in water-use efficiency are consistent with an increase of C4 photosynthesis in high-irradiance-grown F. brownii plants, whereas in the other two genotypes such plasticity seems to be absent. Photosynthetic discrimination against (13)C in the three genotypes was less at high than at low irradiance, with the greatest change occurring in F. brownii. Discrimination against (13)C expressed as δ (13)C was linearly correlated (r (2) = 0.81; P<0.001) with the ratio of bundle-sheath volume to mesophyll cell area when all samples from the three genotypes were combined. This tissue ratio increased for F. brownii and the F1 hybrid as growth irradiance increased, indicating a greater tendency towards Kranz anatomy. The results indicated that F. brownii had plasticity in its C4-related anatomical and physiological characteristics as a function of growth irradiance, whereas plasticity was less evident in the F1 hybrid and absent in F. linearis.

Growth of the C4 dicot Flaveria bidentis: photosynthetic acclimation to low light through shifts in leaf anatomy and biochemistry

“…In addition, the size of the vascular bundles decreased, as did the average size of the bundle sheath cell surrounding them (Table 3). A decrease in leaf thickness in response to low light intensity has been observed previously in studies on both C 3 and C 4 plants (Louwerse and Zweerde, 1977; Bjorkman, 1981; Ward and Woolhouse, 1986 b ; Araus et al , 1991; Sage and McKown, 2006). This trait has been argued to reduce the construction cost per unit leaf area of any new leaves to match the reduced energy input in a low light environment.…”

“…Growth irradiance is known to have considerable effects on growth in C 4 plants, including anatomical, biochemical, and physiological changes to the photosynthetic machinery and operation of the leaves (Ward and Woolhouse, 1986 a , b ; Araus et al , 1991; Tazoe et al , 2006). The experimental set-up included 15 plants grown at two irradiances over 34 d, during which imaging was conducted 13 times (Fig.…”

Effects of Light and Sucrose Levels on the Anatomy, Ultrastructure, and Photosynthesis ofGardenia jasminoidesEllis Leaflets Culturedin vitro

“…Thickness and relative volume of leaflet tissues were measured from light microscope sections as described by Araus et al (1986Araus et al ( , 1991. For each treatment two to three cross sections of different leaflets were used.…”

Genotypic and within canopy variation in leaf carbon isotope discrimination and its relation to short-term leaf gas exchange characteristics in cassava grown under rain-fed conditions in the tropics

“…The only exception in this regard is Flaveria brownii, whose classification status is controversial. Holaday et al (1985Holaday et al ( , 1988 and Araus et al (1990Araus et al ( , 1991 considered it C 4 , then later C 4 -like type, while Monson (1989) treated it as a highly advanced C 3 -C 4 species, based on several anatomical, physiological, and biochemical characteristics. This species exhibits δ 13 C values around -16 to -17, which are within the range observed in C 4 plants .…”