Transcription profiling of Arabidopsis germinating pollen

ABSTRACT: In sexual reproduction, a proper communication and cooperation between male and female organs and tissue are essential for male and female gametes to unite. In flowering plants, female sporophytic tissues and gametophyte direct a male pollen tube towards an egg apparatus, which consists of an egg cell and two synergid cells. The cell-cell communication between the pollen tube and the egg apparatus, such as the reception of a signal from the egg apparatus at the pollen tube, makes the tip of pollen tube rapture to release the sperm cell. To isolate male factors involved in the interaction between a pollen tube and an egg apparatus, we focused on receptor-like kinases (RLKs), which are extensively diversified in the flowering plant lineage to comprise a large monophyletic gene family. Approximately 620 members were found in the Arabidopsis thaliana genome. Expression patterns of 558 RLKs were analyzed using an Affymetrix ATH1 microarray of A. thaliana. We focused on two RLKs, ANXUR1 (ANX1) and ANXUR2 (ANX2), and characterized their function. Here we report that pollen tubes of anx1/anx2 ruptured before arriving at the egg apparatus, suggesting that ANX1 and ANX2 are male factors controlling pollen tube behavior with directing rupture at proper timing. Furthermore, ANX1 and ANX2 were the most closely related paralogs to a female factor FERONIA/SIRENE controlling pollen tube behavior expressed in synergid cells. Our finding shows that the coordinated behaviors of female and male reproductive apparatuses are regulated by the sister genes, whose duplication might play a role in the evolution of fertilization system in flowering plants. Experiment Overall Design: Arabidopsis thaliana Col-0 was grown at 18°C for 8 hr in the dark and at 22°C for 16 hr in the light. To collect germinated pollen with pollen tubes, opened flowers were touched to cellophane layered on the pollen germination medium containing 13.5% sucrose, 10 mM CaCl2, 0.4 mM boric acid, 1 mM KCl, 0.001% myo-inositol, and 0.6% agarose. The released pollen was incubated at 25°C for 6 hr in the dark. For collection of seedlings, seeds were sown on Murashige-Skoog medium containing 1x Murashige and Skoog Plant Salt Mixture (Wako), 1x Gamborg’s vitamin solution (Wako), 1% sucrose, and 0.8% agar. Seedlings including roots with one or two rosette leaves were collected for RNA extraction. RNA was extracted with Isogene (Nippon Gene), precipitated with LiCl, and further purified with RNeasy. The ATH1 genechip (Affymetrix) was used for expression analysis using 10 µg each of total RNA following the manufacturer's instructions. Array data were processed and analyzed with the GCOS1.2 program (Affymetrix) and Excel 2004 (Microsoft). Hybridization with germinating pollen RNA was duplicated and the results were compared to that with seedling RNA.

ORGANISM(S): Arabidopsis thaliana

SUBMITTER: Mitsuyasu Hasebe 

PROVIDER: E-GEOD-12316 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress