'C4 photosynthesis' refers to a suite of traits that increase photosynthesis in high light and high temperature environments. Most C4 plants are grasses, which dominate tropical and subtropical grasslands and savannas but are conspicuously absent from cold growing season climates. Physiological attributes of C4 photosynthesis have been invoked to explain C4 grass biogeography; however, the path...

The evolutionary accessibility of novel adaptations varies among lineages, depending in part on the genetic elements present in each group. However, the factors determining the evolutionary potential of closely related genes remain largely unknown. In plants, CO2-concentrating mechanisms such as C4 and crassulacean acid metabolism (CAM) photosynthesis have evolved numerous times in distantly re...

Upregulation of the C4 metabolic cycle is a major step in the evolution of C4 photosynthesis. Why this happened remains unclear, in part because of difficulties measuring the C4 cycle in situ in C3-C4 intermediate species. Now, Alonso-Cantabrana and von Caemmerer (2016) have described a new approach for quantifying C4 cycle activity, thereby providing the means to analyze its upregulation in an...

The distribution of C3 and C4 plants changed in regionally contrasting ways during the last glacial period. C4 plant expansion in low-latitude Africa and America coincided with C4 plant decreases in Mesoamerica and the US Great Plains. This C4 plant expansion has been attributed to lower pCO2 and increased aridity and the decline in C4 plants is believed to have been caused by increased winter ...

The North American tallgrass prairie is composed of a diverse mix of C3 and C4 plant species that are subject to multiple resource limitations. C4 rasses dominate this ecosystem, purportedly due to greater photosynthetic capacity and resource-use efficiency associated with C4 photosynthesis. e tested the hypothesis that intrinsic physiological differences between C3 and C4 species are consisten...

Differentiating C3 and C4 grass pollen in the paleorecord is difficult because of their morphological similarity. Using a spooling wire microcombustion device interfaced with an isotope ratio mass spectrometer, Single Pollen Isotope Ratio AnaLysis (SPIRAL) enables classification of grass pollen as C3 or C4 based upon d C values. To address several limitations of this novel technique, we expande...

The biochemical and physiological characteristics of C4 photosynthesis have been researched and clarified in detail. We now know that the differentiation of two cell types, mesophyll cells (MC) and bundle sheath cells (BSC), is required for efficient C4 photosynthesis. Thus, the leaves of C4 plants have more complicated structural and functional features than those of C3 plants (Hatch, 1999; Ka...

Global climate change is expected to shift regional rainfall patterns, influencing species distributions where they depend on water availability. Comparative studies have demonstrated that C4 grasses inhabit drier habitats than C3 relatives, but that both C3 and C4 photosynthesis are susceptible to drought. However, C4 plants may show advantages in hydraulic performance in dry environments. We ...

The question then is how the same neurons convey two different sorts of information. The answer is that motor giants are capable of generating two types of action potentials, small/slow calcium spikes and large/fast sodium spikes, depending on the degree of depolarization it receives. As opposed to the input from the ring giant, the input from the pacemaker is too low to trigger the sodium spik...