Light and growth temperature alter carbon isotope discrimination and estimated bundle sheath leakiness in C4 grasses and dicots

Abstract

We combined measurements of short-term (during gas exchange) and long-term (from plant dry matter) carbon isotope discrimination to estimate CO(2) leakiness from bundle sheath cells in six C(4) species (three grasses and three dicots) as a function of leaf insertion level, growth temperature and short-term irradiance. The two methods for determining leakiness yielded similar results (P > 0.05) for all species except Setaria macrostachya, which may be explained by the leaf of this species not being accommodating to gas exchange. Leaf insertion level had no effect on leakiness. At the highest growth temperature (36 degrees C) leakiness was lower than at the two lower growth temperatures (16 degrees C and 26 degrees C), between which no differences in leakiness were apparent. Higher irradiance decreased leakiness in three species, while it had no significant effect on the others (there was an opposite trend in two species). The inverse response to increasing irradiance was most marked in the two NAD-ME dicots (both Amaranthus species), which both showed almost 50% leakiness at low light (300 micromol quanta m(-2) s(-1)) compared to about 30% at high light (1,600 micromol quanta m(-2) s(-1)). NADP-ME subtype grasses had lower leakiness than NAD-ME dicots. Although there were exceptions, particularly in the effect of irradiance on leakiness in Sorghum and Boerhavia, we conclude that conditions favourable to C(4) photosynthesis (high temperature and high light) lead to a reduction in leakiness.

Stable Carbon Isotope Discrimination Is under Genetic Control in the C4 Species Maize with Several Genomic Regions Influencing Trait Expression

“…C of the IL was largely decreased compared with what was observed in C 3 plants (Vogel, 1980) and similar to previous reports for maize (Kubásek et al, 2007;Monneveux et al, 2007;Pengelly et al, 2011). Surprisingly, the absolute range for D 13 C within the IL was not much lower than for a diverse set of International Maize and Wheat Improvement Center hybrid cultivars (Tieszen and Grant, 1990) and close to the absolute range reported for C 3 crops (Henderson et al, 1998;Rebetzke et al, 2008;Xu et al, 2008).…”

The Impacts of Fluctuating Light on Crop Performance

“…This leakiness is energetically costly, since PEP must still be regenerated at the cost of ATP without the usual fixation of carbon (von Caemmerer and Furbank, 1999;Sage and McKown, 2006). Transient increases in leakiness are reported in many C 4 plants in response to low light shifts (Cousins et al, 2006(Cousins et al, , 2008Kubásek et al, 2007;Tazoe et al, 2008;Pengelly et al, 2010), especially under light values lower than 100 mmol m 22 s 21 (Kromdijk et al, 2010;Bellasio and Griffiths, 2014a), although it should be noted that the 13 CO 2 discrimination assumptions used to interpret earlier reports can overstate the impact of transient light to leakiness (Ubierna et al, 2011(Ubierna et al, , 2013Kromdijk et al, 2014). While leakiness in the C 4 carbon pump results in inefficient carbon fixation and transient decreases in the quantum efficiency of C 4 carbon fixation, these losses appear small.…”

Leaf Development in the Single-Cell C4 System in Bienertia sinuspersici: Expression of Genes and Peptide Levels for C4 Metabolism in Relation to Chlorenchyma Structure under Different Light Conditions

“…C value of M leaves became more negative following D treatment, which could occur due to nonphotosynthetic reasons, which are not well defined but include fractionation occurring during respiration (Henderson et al, 1992;Kubasek et al, 2007). With respect to photosynthetic peptides, levels in D-treated M leaves showed a remarkable stability for the retention of photosynthetic enzymes.…”

“…This could reflect increased leakage of CO 2 being delivered by the C 4 cycle to the cytoplasmic compartment containing Rubisco during photosynthesis under LL. It is known that C 4 plants have increased discrimination against fixing 13 CO 2 under LL, indicative of increased leakage (Henderson et al, 1992;Kubasek et al, 2007). While C 4 values have been reported in M leaves of B. sinuspersici grown under ML (Voznesenskaya et al, 2002), in greenhouse-grown plants values ranging from 215.5& to 221.1& (with the latest developing leaves being most negative) have been reported in B. cycloptera (Freitag and Stichler, 2002).…”