Heterogeneity of photosynthesis within leaves is associated with alteration of leaf structural features and leaf N content per leaf area in rice

Abstract

Increasing leaf photosynthesis rate (A) is considered an important strategy to increase C 3 crop yields. Leaf A is usually represented by point measurements, but A varies within each leaf, especially within large leaves. However, little is known about the effect of heterogeneity of A within leaves on rice performance. Here we investigated the changes in gas-exchange parameters and leaf structural and chemical features along leaf blades in two rice cultivars. Stomatal and mesophyll conductance as well as leaf nitrogen (N), Rubisco and chlorophyll contents increased from base to apex; consequently, A increased along leaves in both cultivars. The variation in A, leaf N content and Rubisco content within leaves was similar to the variations among cultivars, and the extent of A heterogeneity within leaves varied between cultivars, leading to different efficiencies of biomass accumulation. Furthermore, variation of A within leaves was closely associated with leaf structural and chemical features. Our findings emphasise that functional changes along leaf blades are associated with structural and chemical trait variation and that variation of A within leaves should be considered to achieve progress in future breeding programs.

Leaf anatomy mediates coordination of leaf hydraulic conductance and mesophyll conductance to CO2 in Oryza

“…S4. An earlier study found that K leaf was linearly correlated with g s across the selected genotypes (R 2 = 0.57, P = 0.007; Xiong et al, 2015c), but the present study found no relationship between g s and either K x or K ox individually (Fig. S4).…”

“…Water transport and CO 2 diffusion inside leaves are two important functional traits that determine the CO 2 assimilation efficiency (Sack & Holbrook, ; Flexas et al ., ). In our previous study (Xiong et al ., ), we found that both leaf hydraulic conductance ( K leaf ) and mesophyll conductance ( g m ) varied widely among Oryza genotypes, and showed a large degree of correlation with one another. In the current study, our detailed examination of leaf functional and anatomical features provides new insight into the variation of K leaf and g m across related genotypes and their correlations.…”

“…Five small leaf discs (c. 10 9 10 mm) were removed from the middle of each leaf sections (the same leaf used for anatomy analysis) (Xiong et al, 2015c). For each genotype, three leaves from different plants were measured.…”

Leaf photosynthetic capacity is regulated by the interaction of nitrogen and potassium through coordination of CO2 diffusion and carboxylation

“…CO 2 conductance includes stomatal conductance ( g s ) and mesophyll conductance ( g m ) (Grassi and Magnani , DaMatta et al ). Increasing leaf N content is beneficial for increasing g s and g m and stimulating CO 2 conductance (Xiong et al ). The AtNRT1.1 nitrate transporter of Arabidopsis thaliana (Arabidopsis) supports stomatal function by adjusting the nitrate concentration in guard cells (Guo et al ).…”

The influence of leaf anatomy on the internal light environment and photosynthetic electron transport rate: exploration with a new leaf ray tracing model

“…2a); however, it has been reported that the chlorophyll concentration in the palisade tissue is higher than that in the spongy tissue (Terashima and Saeki, 1983; Cui et al , 1991), and that the chlorophyll content is highly heterogeneous along the leaves (Xiong et al , 2015). Therefore we also examined the effect of variation in chlorophyll concentration between palisade and spongy chloroplasts on the internal light environment.…”