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Origin and mechanism of crassulacean acid metabolism in orchids as implied by comparative transcriptomics and genomics of the carbon fixation pathway
Author(s) -
Zhang Liangsheng,
Chen Fei,
Zhang GuoQiang,
Zhang YongQiang,
Niu Shance,
Xiong JinSong,
Lin Zhenguo,
Cheng ZongMing Max,
Liu ZhongJian
Publication year - 2016
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/tpj.13159
Subject(s) - crassulacean acid metabolism , carbon fixation , mechanism (biology) , transcriptome , biology , fixation (population genetics) , botany , computational biology , evolutionary biology , chemistry , biochemistry , photosynthesis , gene , gene expression , physics , quantum mechanics
Summary Crassulacean acid metabolism ( CAM ) is a CO 2 fixation pathway that maximizes water‐use efficiency ( WUE ), compared with the C3/C4 CO 2 pathway, which permits CAM plants to adapt to arid environments. The CAM pathway provides excellent opportunities to genetically design plants, especially bioenergy crops, with a high WUE and better photosynthetic performance than C3/C4 in arid environments. The information available on the origin and evolution of CAM is scant, however. Here, we analyzed transcriptomes from 13 orchid species and two existing orchid genomes, covering CAM and C3 plants, with an emphasis on comparing 13 gene families involved in the complete carbon fixation pathway. The dosage of the core photosynthesis‐related genes plays no substantial role in the evolution of CAM in orchids; however, CAM may have evolved primarily by changes at the transcription level of key carbon fixation pathway genes. We proposed that in both dark and light, CO 2 is primarily fixed and then released through two metabolic pathways via known genes, such as PPC 1 , PPDK and PPCK . This study reports a comprehensive comparison of carbon fixation pathway genes across different photosynthetic plants, and reveals the importance of the level of expression of key genes in the origin and evolution of CAM .