Role of cell wall invertase in Arabidopsis ovule development

SJ Liao and Y-L Ruan

School of Environmental and Life Sciences, University of Newcastle, Callaghan, NSW 2308, Australia

Ovule development is essential for realization of crop yield as it determines seed number. Cell wall invertase (CWIN)-mediated sucrose metabolism and signalling is central to plant reproductive development (1). It remains elusive, though, whether and how CWIN controls ovule development, despite observations on the involvement of CWIN in pollen fertility, seed development and stress response across a wide range of species (2,3). We recently discovered that two reproductive specific CWIN genes AtCWIN4 and AtCWIN2 were exclusively and highly expressed in the placenta region of the gynoecium at flower stage 9 in Arabidopsis where ovule initiates. This finding indicates that CWINs have a role in ovule initiation. Consistently, phenotypic analysis of single and double mutants (Atcwin2, Atcwin4, Atcwin2cwin4 and Atcwin4cwin2) revealed a reduction of ovule number, the degree of which was influenced by environmental conditions. Molecular and biochemical analyses showed that the survival of the remaining ovules is most likely due to the residual CWIN activity in these CWIN mutants. Thus, we aim (i) to generate transgenic Arabidopsis with dramatic reduction of CWIN activity by expressing an artificial miRNA against AtCWIN2 and AtCWIN4 under the control of an ovule-specific SEEDSTICK promoter; (ii) to examine the phenotypic effect of down regulation of CWIN on ovule development and (iii) to investigate the molecular mechanism by which CWIN regulates ovule development. We will report the progress of the research in this presentation.
References: (1) Ruan Y-L 2014 Annu Rev Plant Biol 65, 33-67. (2) Palmer WM, Ru L, Jin Y, Patrick JW & Ruan Y-L 2015 Mol Plant 8,315-328. (3) Wang L & Ruan Y-L 2016 Plant Physiol 171, 405-423.