Abstract
Female gametophyte is the multicellular haploid structure that can produce embryo and endosperm after fertilization, which has become an attractive model system for investigating molecular mechanisms in nuclei migration, cell specification, cell-to-cell communication and many other processes. Previous reports found that the small ubiquitin-like modifier (SUMO) E3 ligase, SIZ1, participated in many processes depending on particular target substrates and suppression of salicylic acid (SA) accumulation. Here, we report that SIZ1 mediates the reproductive process. SIZ1 showed enhanced expression in female organs, but was not detected in the anther or pollen. A defect in the siz1-2 maternal source resulted in reduced seed-set regardless of high SA concentration within the plant. Moreover, aniline blue staining and scanning electron microscopy revealed that funicular and micropylar pollen tube guidance was arrested in siz1-2 plants. Some of the embryo sacs of ovules in siz1-2 were also disrupted quickly after stage FG7. There was no significant affects of the siz1-2 mutation on expression of genes involved in female gametophyte development- or pollen tube guidance in ovaries. Together, our results suggest that SIZ1 sustains the stability and normal function of the mature female gametophyte which is necessary for pollen tube guidance.
Highlights
Female gametophyte plays a pivotal role in the sexual reproduction of angiosperms
In terms of the female reproductive organs, GUS expression was high in the style, while a lower level of GUS signal was detected in other parts of the pistil (Figure 1B, C)
Pollen development is essential for plant reproduction, and some proteins have been shown to be involved in successful fertilization by regulating pollen tube growth in Arabidopsis
Summary
Female gametophyte plays a pivotal role in the sexual reproduction of angiosperms. It is the structure that produces the egg cell and central cell which give rise to the seed embryo and endosperm after fertilization, respectively. Elegant cell ablation experiments in Torenia fournieri and studies on a synergid-expressed MYB98 gene in Arabidopsis indicate that synergid cells are the origin of pollen tube guidance signals [3,4]. This is further supported by findings on pollen tube guidance attractants (LUREs) in Torenia fournieri [5]. Studies on synergidand egg-expressed signal protein ZmEA1 in maize (Zea mays) [6], central cell guidance (ccg) and the GABA Transaminase (pop2) mutants in Arabidopsis [7] provide evidences that other cells in or surrounding the embryo sac would function in pollen tube guidance. No study focus on how does the mature female gametophyte maintain its function
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
