Pollen and plant reproduction biology: blooming from East to West.

The idea of assembling a Special Issue on Pollen Tube and Reproduction in Molecular Plant was conceived during the organization of the 2012 Pollen Biology International Symposium and Workshop held at the Shanghai Institute of Plant Physiology and Ecology (SIPPE), Chinese Academy of Science (CAS), 27–31 October 2012. Wei-Hua Tang of the SIPPE led the organization, with the support of Hong-Wei Xue, Director of SIPPE acting as Chair of the Organization Committee. The 2-d symposium was attended by about 100 international participants and focused on reports and discussions on the most recent research activities in the field. The 2-d workshop that followed provided a forum for in-depth introduction on various aspects of pollen and plant reproduction biology to about 200 graduate students, postdoctoral fellows, and new investigators to the field. A comprehensive report of the Shanghai Symposium (contributed by Irene Lavagi, UC Riverside) had already appeared in the Plant Reproduction Newsletter published by the International Association of Sexual Plant Reproduction Research (www.iasprr.org/). Here, we provide just a summary of the Symposium and how its theme is reflected in this Special Issue. Additionally, since the Shanghai Symposium and Workshop was conceived by the Pollen Biology Research Coordination Network (Pollen RCN from hereon, http://pollennetwork.org/), a US National Science Foundation (NSF)supported effort to achieve broad international participation in pollen research, we also briefly mention salient discussions of topics covered by two other Pollen RCN-sponsored meetings to highlight the vibrancy of the field and international collaboration among the pollen and plant reproduction research community. The cell biological process of pollen tube growth and modeling of this dramatic polarized cell growth process were featured prominently at the Shanghai Symposium. The talks covered key cellular components of the cytoskeleton, the endomembrane trafficking system, regulators of ion (e.g. H+ and Ca2+) dynamics, and various aspects of the RAC/ROP GTPase molecular switch at the pollen tube tip. Perhaps more importantly, much of these discussions focused on how these recent findings might be linked to the control of exoand endocytosis and spatially and temporally regulated membrane expansion and wall deposition which together underlie the pollen tube tip-growth process. The Shanghai Symposium represented a continuation of discussions started in the Second Annual Pollen RCN meeting that took place in August 2011 in Minneapolis, MN, USA (programs for the RCN annual meetings and the Shanghai Symposium and Workshop are available at http://pollennetwork.org/). Pollen tube modeling was the featured topic of that meeting. It was apparent from these biological and computational discussions that knowledge of the pollen tube growth cell biological process is advanced enough to support the formulation of predictive modeling, which should help integrate the multiple facets of the pollen tube to provide a ‘systems understanding’ of this dramatic polarized cell growth process. The invited reviews of this Special Issue (Chebli et al., 2013; Guan et al., 2013; Hepler et al., 2013) provide excellent overviews of those areas as well as discussions on some of the unresolved questions in these areas. That these topics continue to be active areas of research is evidenced by at least six papers (Chen et al., 2013; Idilli et al., 2013; Li et al., 2013; Mähs et al., 2013; Wang et al., 2013) that were submitted in response to the call for papers for this Special Issue, as well as several previously accepted papers whose authors have opted for inclusion in this issue. The Shanghai Symposium also featured many exciting talks on the recent discoveries in male–female interactions that underlie the reproductive process. Yan Zhang (Shangtong Agricultural University) summarized findings reported in many of these talks most humorously by commenting that ‘She’s the boss ...’ (Kessler and Grossniklaus,