Publications
Citation
VanBuren R, Wai J, Zhang Q, Song X, Edger PP, Bryant D, Michael TP, Mockler TC, Bartels D
Seed Desiccation Mechanisms Co-opted for Vegetative Desiccation in the Resurrection Grass Oropetium Thomeaum.
Plant, Cell & Environment. 2017 Jul 20;.
Abstract
Resurrection plants desiccate during periods of prolonged drought stress, then resume normal cellular metabolism upon water availability. Desiccation tolerance has multiple origins in flowering plants and it likely evolved through rewiring seed desiccation pathways. Oropetium thomaeum is an emerging model for extreme drought tolerance and its genome, which is the smallest among surveyed grasses, was recently sequenced. Combining RNA-seq, targeted metabolite analysis, and comparative genomics, we show evidence for co-option of seed specific pathways during vegetative desiccation. Desiccation related gene-coexpression clusters are enriched in functions related to seed development including several seed specific-transcription factors. Across the metabolic network, pathways involved in programed cell death inhibition, ABA signaling, and others are activated during dehydration. Oleosins and oil bodies that typically function in seed storage are highly abundant in desiccated leaves and may function for membrane stability and storage. Orthologs to seed-specific LEA proteins from rice and maize have neofunctionalized in Oropetium with high expression during desiccation. Accumulation of sucrose, raffinose, and stachyose in drying leaves mirrors sugar accumulation patterns in maturing seeds. Together, these results connect vegetative desiccation with existing seed desiccation and drought responsive pathways and provide some key candidate genes for engineering improved drought tolerance in crop plants.