Recently, Ph.D. student Shaobao Liu from BEBC
has published his research paper in Soft Matter entitled “Fountain
streaming contributes to fast tip-growth through regulating the gradients of
turgor pressure and concentration in pollen tubes ".
Fast
tip growth of pollen tube is a vital process in sexual plant reproduction. In
the process of sexual reproduction of higher plants, the growth rate of pollen
tubes at up to 0.6 mm/h (the fastest growing plant cell types known) is rather
impressive. Fountain streaming is a typical microfluidic patterned activity
within plant cells, especially for cells with high aspect ratio such as pollen
tube. Fountain streaming plays crucial roles in the transport of nutrients and
metabolites, the positioning of organelles and the mixing of cytoplasm,
whereas, its implications for the fast tip growth of pollen tube remain a
mystery. In this paper, based on the observations of asiatic
lily Lilium Casablanca, physical models of
fountain streaming in pollen tubes were introduced to solve the hydrodynamics
and advection-diffusion dynamics of viscous Stokes flow in the shank and apical
region of a pollen tube. Theoretical and numerical results demonstrated that
the gradients of turgor pressure and concentration
along the length of pollen tubes continuously provide undamped driving force
and rich materials transport for the fast tip growth of pollen tubes. Simple
experiments confirm that the tip shape and growth rate of pollen tube were
influenced by the changes of turgor pressure gradients induced by osmotic
stress. The proposed models and experimental verifications provide mechanistic
insight into fountain streaming that positively contributes to the fast pollen
tube tip growth process.
These may be helpful for further understanding the sexual reproduction and
infertility of flowering plants under normal conditions and drought stress.
The work is under the guidance of Profs. Feng Xu
and Tianjian Lu. The co-authors of the paper include Han Liu (Co-first author),
ShangSheng Feng, Min Lin, Feng Xu and Tian Jian Lu. This paper has been
selected as the Inside Front Cover of Soft Matter.
Paper
link: http://pubs.rsc.org/en/content/articlepdf/2017/sm/c6sm01915c
