A pinboard by
Maria-Cecilia Costa

Post-doctoral fellow, University of Cape Town


The ability of resurrection plants to withstand drought holds the key to make drought tolerant crops

Climate change is widely recognized as the major environmental problem the world is facing, with negative impacts on crop production and food security. The projections of increased global demand for crop calories and increased frequency and severity of drought episodes are expediting the development of crop varieties that can yield well under harsh environmental conditions. Developing countries are particularly at risk, as they struggle to maintain robust breeding capabilities and need support for the development of stress tolerant crops critical for food security. While efforts have been made to develop crops that better survive such conditions, few studies have improved the crop’s ability to tolerate drought. Such plants still die during extended droughts as they inevitably dehydrate below critical levels. It is thus imperative to rapidly find innovative solutions to minimise the potentially devastating impacts of drought. Research on plants that naturally tolerate both extreme water loss, such as resurrection plants, present a unique solution to this problem. The African resurrection plant Xerophyta viscosa is a close relative to cereal staple crops and thus can provide key information for the development of crop varieties better able to survive drought and produce a harvestable yield under drought. I study Xerophyta from a molecular and physiologic point of view to understand better the mechanisms it uses to tolerate extreme water loss. My goal is to identify which of these mechanisms can be used for plant breeders to create crop varieties able to tolerate drought without compromising yield. My team has already identified some of these mechanisms, such as the accumulation of protective molecules and powerful antioxidants. Our next step is to induce them in a crop and assess the efficacy in improving drought tolerance and the effects on yield under drought and optimal conditions.


Seed desiccation mechanisms co-opted for vegetative desiccation in the resurrection grass Oropetium thomeaum.

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.

Pub.: 22 Jul '17, Pinned: 17 Aug '17