PLANT BIOLOGY AND BIOTECHNOLOGY / Plant Systems Biology
Plant systems biology, plant microbiome, salinity stress, hormone signaling, auxin biosynthesis, second messenger signaling, ion homeostasis and membrane transport, plant-pathogen interactions.
Description of Research
Soil salinity affects 20% of cultivated land and drastically reduces the yield of crop plants. Salinity stress inhibits plant growth in two phases: a shoot ion-independent phase that occurs within minutes of exposure and an ion-dependent phase that occurs several days later after Na+ ions have accumulated to toxic levels. Our lack of understanding of how plants respond to these different phases of salinity stress limits our ability to identify genetic determinants of salt tolerance.
My Group has compared the transcriptomes of plants grown under saline conditions with plants grown under osmotic stress conditions that mimic the shoot ion-independent phase of salinity stress and identified genes that specifically respond to salt (ion-dependent). Computational analysis of these salt-specific genes has revealed that genes whose expression increases specifically in response to salt are enriched in the functional term “response to auxin”. We thus hypothesise that auxin enables plants to grow under saline conditions. We have since identified an auxin biosynthesis gene, NITRILASE 2, whose expression is increased in response to salt and shown that auxin levels are elevated in plants under saline conditions compared to plants grown under osmotic stress conditions. Additionally, plants that overexpress NITRILASE 2 make more auxin under saline conditions and are more salt tolerant. We are currently identifying transcription factors that regulate the expression of NITRILASE 2 and investigating the mechanism by which elevated auxin levels could improve plant salt tolerance (either by modulating cell expansion or ion homeostasis). Finally, we are performing preliminary experiments to determine whether our foundational research in the model plant Arabidopsis, is transferable to locally relevant crop plants such as maize and sorghum.
At the ICGEB I am also involved in inter-component collaborative projects that aim to understand the microbiome of crop plants like sorghum in order to identify bacteria that promote growth and abiotic stress tolerance.
The Group has recently reported how auxin levels are affected in saline conditions, using Arabidopsis as model (Cackett et al., Front Plant Sci, 2022). Methods 16:47, 2020).
Oyeniran, K.A., Hartnady, P., Claverie, S., Lefeuvre, P., Monjane, A.L., Lett, J-M, Donaldson, L.,Varsani, A. and Martin, D.P. (2021) How virulent are emerging maize-infecting mastreviruses? Archives of Virology 166(3):955-959 PubMed link
Wong, A., Donaldson L., Portes, M.T., Eppinger, J., Feijó, J. and Gehring, C. 2020. The Arabidopsis Diacylglycerol Kinase 4 is involved in nitric oxide-dependent pollen tube guidance and fertilization. Development 147, dev183715 PubMed link
Al-Younis, I., Wong, A., Lemtiri-Chlieh, F., Schmӧckel, S., Tester, M., Gehring, C. and Donaldson, L. 2018. The Arabidopsis thaliana K+-uptake permease 5 (AtKUP5) contains a functional cytosolic adenylate cyclase essential for K+ transport. Frontiers in Plant Science 9: 1645 PubMed link
Donaldson, L.E., Meier, S.K. and Gehring, C.A. 2016. The Arabidopsis cyclic nucleotide interactome. Cell Communication and Signaling 14: 10 PubMed link
Ruzvidzo, O., Donaldson, L., Valentine, A. and Gehring, C. (2011) The Arabidopsis thaliana natriuretic peptide AtPNP-A is a systemic regulator of leaf dark respiration and signals via the phloem. Journal of Plant Physiology 168: 1710-1714 PubMed link
Donaldson, L.E., Ludidi, N.N., Knight, M.R., Gehring, C. and Denby, K.J. 2004. Salt and osmotic stress cause rapid increases in Arabidopsis thaliana cGMP levels. FEBS Letters 569: 317-320 PubMed link