期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2022
卷号：119
期号：5
DOI：10.1073/pnas.2118886119
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Significance
This is a significant sister group contrast comparative study of the underpinning genomics and evolution of desiccation tolerance (DT), a critical trait in the evolution of land plants. Our results revealed that the DT grass
Sporobolus stapfianus is transcriptionally primed to tolerate a dehydration/desiccation event and that the desiccation response in the DT
S. stapfianus is distinct from the water stress response of the desiccation-sensitive
Sporobolus pyramidalis. Our results also show that the desiccation response is largely unique, indicating a recent evolution of this trait within the angiosperms, and that inhibition of senescence during dehydration is likely critical in rendering a plant desiccation tolerant.
Desiccation tolerance is an ancient and complex trait that spans all major lineages of life on earth. Although important in the evolution of land plants, the mechanisms that underlay this complex trait are poorly understood, especially for vegetative desiccation tolerance (VDT). The lack of suitable closely related plant models that offer a direct contrast between desiccation tolerance and sensitivity has hampered progress. We have assembled high-quality genomes for two closely related grasses, the desiccation-tolerant
Sporobolus stapfianus and the desiccation-sensitive
Sporobolus pyramidalis. Both species are complex polyploids;
S. stapfianus is primarily tetraploid, and
S. pyramidalis is primarily hexaploid.
S. pyramidalis undergoes a major transcriptome remodeling event during initial exposure to dehydration, while
S. stapfianus has a muted early response, with peak remodeling during the transition between 1.5 and 1.0 grams of water (gH
2O) g
−1 dry weight (dw). Functionally, the dehydration transcriptome of
S. stapfianus is unrelated to that for
S. pyramidalis. A comparative analysis of the transcriptomes of the hydrated controls for each species indicated that
S. stapfianus is transcriptionally primed for desiccation. Cross-species comparative analyses indicated that VDT likely evolved from reprogramming of desiccation tolerance mechanisms that evolved in seeds and that the tolerance mechanism of
S. stapfianus represents a recent evolution for VDT within the Chloridoideae. Orthogroup analyses of the significantly differentially abundant transcripts reconfirmed our present understanding of the response to dehydration, including the lack of an induction of senescence in resurrection angiosperms. The data also suggest that failure to maintain protein structure during dehydration is likely critical in rendering a plant desiccation sensitive.
关键词：endesiccation tolerancesister group contrastcomparative genomicstranscriptome remodelingC4 grasses
