Women’s Forum: Tell us a little bit about your research on “resurrection plants” that “come back to life”, and what it might mean for SIDS, the African continent, and perhaps the world.
Resurrection plants were so called because of their ability to appear dead for months to years and yet green up and start growing again when it rained. We now know that these plants are not dead, just extremely dry (<5% cellular water content) and in a “quiescent/dormant” state until water is resupplied, after which they resume full metabolic activity in existing tissues within 12-48hours. The ability to tolerate this extreme water loss (termed desiccation tolerance) for prolonged periods of time is common in seeds, but very rare in vegetative tissues, with only 135 Angiosperm species known to date to possess this trait. This fact is of relevance in two regards:
- Resurrection plants have a very unusual and unique way of surviving prolonged droughts. The vegetative tissues of most other plants (and all crops) tolerate very little water loss, surviving brief spells of drought by preventing (resisting) water loss from such tissues by various well known mechanisms. However, in prolonged droughts, such resistance mechanisms fail, water deficit stress occurs and crop loss is inevitable. Thus resurrection plants serve as excellent models for designing crops with properties of surviving water loss when resistance mechanisms fail.
- My research has shown that there is considerable similarity in the mechanisms employed to enable desiccation tolerance in seeds and vegetative tissues of resurrection plants. Collaborators and I have proposed that vegetative desiccation tolerance arose by “retasking” seed genes to become operative in vegetative tissues under severe drought conditions.
I have utilized a multidisciplinary systems biology approach in order to gain a comprehensive fundamental understanding of the mechanisms associated with vegetative and seed desiccation tolerance. Techniques associated with molecular biology have been employed for inter alia genome sequencing and characterisation of genes, proteins, metabolites and lipids associated with water loss, and the nature of their subcellular regulation. Biochemical, biophysical, physiological and cell biology studies have been employed for functional analysis of how protection is afforded and where it is located.
In parallel, and with growing understanding of what is required for tolerance of extreme water loss, we have initiated conventional biotechnological studies in which key genes are being transformed into crops for testing of improved drought tolerance. Maize, being a staple crop in much of Africa, is a crop that collaborators in my group have targeted with some success. While such approaches in general have resulted in some improvement in tolerance to water deficit, they suffer from the drawbacks of transgenerational instability and, more importantly, from the plasticity of a trait which is attained by only small effects generated by each of the genes included. We are thus also attempting a radically different approach as outlined below.
As indicated in 2 above, we have identified commonality in genes and gene pathways used in the attainment of DT in both seeds and resurrection plants. The implications of this is that all modern crops have the genetic ability for vegetative DT, but genes enabling this remain silenced under drought conditions. We intend to further understand the genetic and regulatory mechanisms enabling vegetative DT and ultimately induce such properties in select crops to enable extreme drought tolerance. This approach is more likely to produce an extremely drought tolerant phenotype, since it will target multiple gene pathways, potentially regulated by a few ‘master’ genes.
My intent is to extend our applied studies to include ‘orphan’ crops typically grown in Africa, such as tef, bambara beans, sorghum and millet.
Given that drought is the largest threat to world agriculture, and that climate models predict increased desertification in tropical and mid latitude regions due to raising temperatures and declining and unpredictable rainfall, production of truly drought tolerant crops will contribute toward food security for many areas of the globe.
Women’s Forum: As one of the few women in your field, have you had to face some challenges in your professional life? If so, which ones?
Interestingly, I have not had to face too many challenges, other than the (relatively prevalent) fact that obtaining funding is notoriously difficult. I have had the experience of what I would assume is “professional jealousy” from some individuals. Among men, the inference would be that I have obtained the awards that I have simply because I am a woman in this day and age where recognition of women is of societal relevance. Among women, the inferences and behaviour is more subtle.
What I do find, and I guess this is typical of many women, that it is difficult to say “no”. Being perceived as a successful woman means that I am tasked with way too many requests that I inevitably end up working long hours. My last holiday taken was in 2008!