Sulfinylated azadecalins act as functional mimics of a pollen germination stimulant in Arabidopsis pistils

Abstract

SUMMARY Polarized cell elongation is triggered by small molecule cues during development of diverse organisms. During plant reproduction, pollen interactions with the stigma result in the polar outgrowth of a pollen tube, which delivers sperm cells to the female gametophyte to effect double fertilization. In many plants, pistils stimulate pollen germination. However, in Arabidopsis, the effect of pistils on pollen germination and the pistil factors that stimulate pollen germination remain poorly characterized. Here, we demonstrate that stigma, style, and ovules in Arabidopsis pistils stimulate pollen germination. We isolated an Arabidopsis pistil extract fraction that stimulates Arabidopsis pollen germination, and employed ultrahigh resolution ESI FT-ICR and MS/MS techniques to accurately determine the mass (202.126 daltons) of a compound that is specifically present in this pistil extract fraction. Using the molecular formula (C10H19NOS) and tandem mass spectral fragmentation patterns of the m/z (mass to charge ratio) 202.126 ion, we postulated chemical structures, devised protocols, synthesized N-Methanesulfinyl 1- and 2-azadecalins that are close structural mimics of the m/z 202.126 ion, and showed that they are sufficient to stimulate Arabidopsis pollen germination in vitro (30 µM stimulated ~50% germination) and elicit accession-specific response. Although N-Methanesulfinyl 2-azadecalin stimulated pollen germination in three species of Lineage I of Brassicaceae, it did not induce a germination response in Sisymbrium irio (Lineage II of Brassicaceae) and tobacco, indicating that activity of the compound is not random. Our results show that Arabidopsis pistils promote germination by producing azadecalin-like molecules to ensure rapid fertilization by the appropriate pollen.

Analysis of T-DNA alleles of flavonoid biosynthesis genes in Arabidopsis ecotype Columbia

“…These mutations, all within the same genetic background, could greatly enhance our understanding of the regulation and dynamics of this channeling, which has broad reaching implications across metabolic research areas. The CHS mutant allele, tt4-13, has already been used by our group and others to further probe the involvement of this pathway in modulating the distribution of auxin and ethylene within Arabidopsis seedling roots [7,29,36,50], to characterize the distribution of flux among branch pathways of flavonoid metabolism [45], and to identify molecules that promote pollen fertilization in Arabidopsis [51]. The CHI allele, tt5-3, has been used in a metabolic profiling analysis of the response to UV light [52], whereas tt5-2 was used to demonstrate a requirement for this CHI gene, among flavonoid genes, for flavonol synthesis in pollen [30].…”

In vivo fertilization of banana

“…Both pollen and pistil produce essential compounds to ensure successful pollen germination (QIN et al, 2011;BOAVIDA et al, 2011). In many interspecifi c crosses, the incompatibility reaction of the pollen-pistil occurs because the pollen tube growth of one species is hindered in the stigma of the other.…”

Chang's meaning of capacitation: A molecular perspective

“…Modifications to these metrics by female molecules have also been observed in sperm from other vertebrates, like amphibians (Krapf et al, ), or invertebrates, like sea urchins (Guerrero et al, ; Loza‐Huerta et al, ). Interestingly, pollen tubes (male structures that contains two sperm) grown on pistils (the female reproductive organ) germinate better (Qin et al, ), grow faster and longer (Palanivelu and Johnson, ), and find and target ovules at an enhanced frequency compared to tubes grown in vitro (Palanivelu and Preuss, )—indeed, these pistil‐induced changes in pollen tubes may be functionally analogous to those observed during sperm capacitation.…”