The Physiological Ecology of C4 Photosynthesis

Sage, Rowan F.; Pearcy, Robert W.

doi:10.1007/0-306-48137-5_21

Cited by 71 publications

(38 citation statements)

References 151 publications

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“…This includes close vein spacing and large numerous plastids of the inner BS. Together, these characters enable C 4 plants to thrive in environments that induce high rates of photorespiration in C 3 plants, such as the tropics or grassland savannas (Sage et al, 1999;Sage and Pearcy, 2000). An added benefit of the C 4 syndrome is improved nitrogen and water use efficiencies that have likely contributed to their global distribution and high rates of productivity (Sage, 2004;Tilman et al, 2006;Edwards and Smith, 2010 Walt Whitman wrote these words over one and half centuries ago (Whitman, 1855), and in many ways they are as true today as they were then.…”

Section: Why Study C 4 ?mentioning

confidence: 99%

Setaria viridis: A Model for C4 Photosynthesis

et al. 2010

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C 4 photosynthesis drives productivity in several major food crops and bioenergy grasses, including maize (Zea mays), sugarcane (Saccharum officinarum), sorghum (Sorghum bicolor), Miscanthus x giganteus, and switchgrass (Panicum virgatum). Gains in productivity associated with C 4 photosynthesis include improved water and nitrogen use efficiencies. Thus, engineering C 4 traits into C 3 crops is an attractive target for crop improvement. However, the lack of a small, rapid cycling genetic model system to study C 4 photosynthesis has limited progress in dissecting the regulatory networks underlying the C 4 syndrome. Setaria viridis is a member of the Panicoideae clade and is a close relative of several major feed, fuel, and bioenergy grasses. It is a true diploid with a relatively small genome of ;510 Mb. Its short stature, simple growth requirements, and rapid life cycle will greatly facilitate genetic studies of the C 4 grasses. Importantly, S. viridis uses an NADP-malic enzyme subtype C 4 photosynthetic system to fix carbon and therefore is a potentially powerful model system for dissecting C 4 photosynthesis. Here, we summarize some of the recent advances that promise greatly to accelerate the use of S. viridis as a genetic system. These include our recent successful efforts at regenerating plants from seed callus, establishing a transient transformation system, and developing stable transformation. Why Study C 4 ?C 4 photosynthesis is the primary mode of carbon capture for some of the world's most important food, feed, and fuel crops, including maize (Zea mays), sorghum (Sorghum bicolor), sugarcane (Saccharum officinarum), millets (e.g. Panicum miliaceum, Pennisetum glaucum, and Setaria italica), Miscanthus x giganteus, and switchgrass (Panicum virgatum). In contrast with C 3 plants, C 4 plants first fix CO 2 into a C 4 acid before delivering the CO 2 to the Calvin cycle (Hatch and Slack, 1966;Hatch, 1971). For example, in maize and sorghum leaves, CO 2 entering mesophyll (M) cells is first fixed into oxaloacetate, which is then reduced to malate in the M chloroplasts. The malate then diffuses into the inner bundle sheath (BS) cells and is transported into the BS chloroplast. There, malate is decarboxylated by NADP-malic enzyme, releasing CO 2 close to ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco). This carbon shuttle greatly lowers rates of photorespiration as Rubisco is both isolated from the site of O 2 evolution (oxygen evolving complex of photosystem II) and also maintained in a CO 2 -rich environment. Indeed, in mature maize or sorghum leaves, rates of photorespiration are at the limits of detection under conditions where C 3 plants lose up to 30% of their photosynthetic capacity due to photorespiration (Zhu et al., 2008).

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Section: Why Study C 4 ?mentioning

confidence: 99%

Setaria viridis: A Model for C4 Photosynthesis

et al. 2010

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“…Since C 4 plants are predominantly herbaceous, only rarely achieving the stature of shrubs or small trees (Sage 2001), they are rapidly overtaken in height by forest trees or savannah shrubs and suppressed by shading. Most C 4 plants cannot tolerate shading of sunlight to below 25% of its open sky value, possibly because of anatomical (Ogle 2003), phylogenetic, environmental or physiological constraints (reviewed by Sage & Pearcy 2000). Closed forest, therefore, precludes ecosystem dominance by C 4 plants, but is replaced by open woodland, savannah or grassland in seasonally arid climates because of water-shortage and disturbance by fire (Bond et al 2005).…”

Section: Alternative Mechanisms For C 4 Successmentioning

confidence: 99%

Nature's green revolution: the remarkable evolutionary rise of C₄plants

Osborne

Beerling

2005

Phil. Trans. R. Soc. B

225

151

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Plants with the C 4 photosynthetic pathway dominate today's tropical savannahs and grasslands, and account for some 30% of global terrestrial carbon fixation. Their success stems from a physiological CO 2 -concentrating pump, which leads to high photosynthetic efficiency in warm climates and low atmospheric CO 2 concentrations. Remarkably, their dominance of tropical environments was achieved in only the past 10 million years (Myr), less than 3% of the time that terrestrial plants have existed on Earth. We critically review the proposal that declining atmospheric CO 2 triggered this tropical revolution via its effects on the photosynthetic efficiency of leaves. Our synthesis of the latest geological evidence from South Asia and North America suggests that this emphasis is misplaced. Instead, we find important roles for regional climate change and fire in South Asia, but no obvious environmental trigger for C 4 success in North America. CO 2 -starvation is implicated in the origins of C 4 plants 25-32 Myr ago, raising the possibility that the pathway evolved under more extreme atmospheric conditions experienced 10 times earlier. However, our geochemical analyses provide no evidence of the C 4 mechanism at this time, although possible ancestral components of the C 4 pathway are identified in ancient plant lineages. We suggest that future research must redress the substantial imbalance between experimental investigations and analyses of the geological record.

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“…As a result climate change will affect crop-weed interactions disproportionately depending on the photosynthetic pathway of the crop and weed species (Ziska 2001(Ziska , 2003. C 3 and C 4 species occupy a temporal niche in natural vegetation that is determined by temperature (see Sage and Pearcy 2000). This is also evident in arable weed communities since C 4 weeds usually occur in C 4 crops (e.g.…”

Section: Introductionmentioning

confidence: 99%

Impact of temperature and germination time on the success of a C4 weed in a C3 crop: Amaranthus retroflexus and spring barley

Hyvönen¹

2008

AFSci

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Elevation in temperatures due to climate change could promote the invasion by C4 weed species of arable fields in the boreal region, which are dominated by C 3 crops. The success of Amaranthus retroflexus L. (a C 4 weed) in spring barley (a C 3 crop) was studied at current and elevated temperatures (3 °C difference) in a greenhouse experiment in southern Finland. The competition treatments included no competition and four levels of competition with barley, differing in terms of germination time. The success of A. retroflexus was measured as growth (height and biomass) and seed production (number and biomass). Elevation in temperature enhanced seed production of A. retroflexus, but the impact on growth was minor (only difference in plant height in one treatment). The growth and seed production of A. retroflexus in competition with barley was minimal although the growth of barley decreased with the rise in temperature. The results indicate that climate change could improve growth of a C 4 weed such as A. retroflexus, but it is unlikely to succeed in spring barley.

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The Physiological Ecology of C4 Photosynthesis

Cited by 71 publications

References 151 publications

Setaria viridis: A Model for C4 Photosynthesis

Setaria viridis: A Model for C4 Photosynthesis

Nature's green revolution: the remarkable evolutionary rise of C₄plants

Impact of temperature and germination time on the success of a C4 weed in a C3 crop: Amaranthus retroflexus and spring barley

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The Physiological Ecology of C4 Photosynthesis

Cited by 71 publications

References 151 publications

Setaria viridis: A Model for C4 Photosynthesis

Setaria viridis: A Model for C4 Photosynthesis

Nature's green revolution: the remarkable evolutionary rise of C4plants

Impact of temperature and germination time on the success of a C4 weed in a C3 crop: Amaranthus retroflexus and spring barley

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Nature's green revolution: the remarkable evolutionary rise of C₄plants