In:
Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 110, No. 4 ( 2013-01-22), p. 1381-1386
Abstract:
C 4 photosynthesis is a series of anatomical and biochemical modifications to the typical C 3 pathway that increases the productivity of plants in warm, sunny, and dry conditions. Despite its complexity, it evolved more than 62 times independently in flowering plants. However, C 4 origins are absent from most plant lineages and clustered in others, suggesting that some characteristics increase C 4 evolvability in certain phylogenetic groups. The C 4 trait has evolved 22–24 times in grasses, and all origins occurred within the PACMAD clade, whereas the similarly sized BEP clade contains only C 3 taxa. Here, multiple foliar anatomy traits of 157 species from both BEP and PACMAD clades are quantified and analyzed in a phylogenetic framework. Statistical modeling indicates that C 4 evolvability strongly increases when the proportion of vascular bundle sheath (BS) tissue is higher than 15%, which results from a combination of short distance between BS and large BS cells. A reduction in the distance between BS occurred before the split of the BEP and PACMAD clades, but a decrease in BS cell size later occurred in BEP taxa. Therefore, when environmental changes promoted C 4 evolution, suitable anatomy was present only in members of the PACMAD clade, explaining the clustering of C 4 origins in this lineage. These results show that key alterations of foliar anatomy occurring in a C 3 context and preceding the emergence of the C 4 syndrome by millions of years facilitated the repeated evolution of one of the most successful physiological innovations in angiosperm history.
Type of Medium:
Online Resource
ISSN:
0027-8424
,
1091-6490
DOI:
10.1073/pnas.1216777110
Language:
English
Publisher:
Proceedings of the National Academy of Sciences
Publication Date:
2013
detail.hit.zdb_id:
209104-5
detail.hit.zdb_id:
1461794-8
SSG:
11
SSG:
12
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