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The role of pollen starch accumulation in responses of wheat to water stress and film antitranspirant

Primary Supervisor: Professor Peter Kettlewell, Crop & Environmental Sciences

Secondary supervisor: Dr Philippa Borrill (University of Birmingham - UoB)

PhD project title: The role of pollen starch accumulation in responses of wheat to water stress and film antitranspirant

University of Registration: Harper Adams University

Drought is a major cause of loss in world wheat production, and although drought has damaging effects at all stages of development of the crop, there is a long history of research to establish whether any stages are especially sensitive. A comprehensive review of seven decades of research from the 1890’s to the 1960’s on the timing of drought and irrigation concluded that cereal crops ‘…show a marked sensitivity to water supply during the formation of the reproductive organs…’ (Salter & Goode, 1965). Subsequently, it has been shown that the most sensitive stage in wheat crops is meiosis in the pollen mother cells during inflorescence development. Drought at this stage appears to lead to pollen sterility, reduced seed set and lower grain yield (Saini & Westgate, 1999). Pollen sterility from water stress in wheat appears to relate to less starch accumulation and reduced expression of cell wall invertase genes in cultivars differing in drought tolerance (Ji et al., 2011).

Preliminary evidence from field experiments at HAU indicate that improving leaf water potential (less negative) at meiosis with a film antitranspirant (AT) spray (which reduces water loss from leaves) is associated with more pollen grains accumulating starch and greater grain yield (Weerasinghe et al., 2016). Greater understanding of the mechanism will have potential impact on both management of water-stressed wheat crops and breeding of drought-tolerant varieties.

The aim of this project is to understand the physiological and molecular basis of pollen starch accumulation in wheat varying in water stress severity from AT.

The detailed objectives and experiments will be developed following a thorough review of the literature, but at this stage probable objectives could include:

  1. To test repeatability of improved pollen starch accumulation and greater grain number and yield in response to less water stress from AT.
  2. To examine transcriptome responses in pollen in response to less water stress from AT.
  3. To target loci selected on combined evidence from literature and transcriptomics for gene expression studies.

These objectives will be mainly tested in plants from a series of three annual field experiments at HAU conducted under rainshelters with controlled water supply to simulate a field crop as closely as possible. Molecular work will be undertaken at UoB.

References:

  1. Ji, X., Shiran, B., Wan, J., Lewis, D.C., Jenkins, C.L.D., Condon, A.G., Richards, R.A., Dolferus, R. (2010) Importance of pre-anthesis anther sink strength for maintenance of grain number during reproductive stage water stress in wheat. Plant, Cell and Environment 33:926–942.
  2. Saini, H. S., Westgate, M. E. (1999). Reproductive development in grain crops during drought. Advances in Agronomy68:59-96.
  3. Salter, P. J., Goode, J. E. (1967). Crop Responses to Water at Different Stages of Growth. Commonwealth Agricultural Bureaux, Farnham Royal, UK.
  4. Weerasinghe, M.M., Kettlewell, P.S., Grove, I.G., Hare, M.C. (2016) Evidence for improved pollen viability as the mechanism for film antitranspirant mitigation of drought damage to wheat yield. Crop and Pasture Science 67:137-146.

BBSRC Strategic Research Priority: Sustainable Agriculture and Food: Plant and Crop Science

Contact: Professor Peter Kettlewell, Harper Adams University