Journal
FRONTIERS IN PLANT SCIENCE
Volume 6, Issue -, Pages -Publisher
FRONTIERS MEDIA SA
DOI: 10.3389/fpls.2015.00197
Keywords
pollen; temperature stress tolerance; lipid flippases; phosphatidic acid; phosphatidylinositol
Categories
Funding
- National Science Foundation [NSF DBI-0420033]
- National Institutes of Health [NIH 1RO1 GM070813-01]
- US Department of Energy [DE-FG03-94ER20152]
- Hatch grant through the Nevada Agriculture Experiment Station. Bioinformatics was made possible by the INBRE Program of the National Center for Research Resources [P20 RR-016464]
- COBRE program of the National Institutes of Health [RR024210]
- Danish National Research Foundation [DNRF85]
- Danish Council for Independent Research, Natural Sciences (FNU project) [10-083406]
- National Science Foundation's EPSCoR program [EPS-0236913]
- State of Kansas through Kansas Technology Enterprise Corporation
- Kansas State University
Ask authors/readers for more resources
Members of the P4 subfamily of P-type ATPases are thought to create and maintain lipid asymmetry in biological membranes by flipping specific lipids between membrane leaflets. In Arabidopsis, 7 of the 12 Aminophospholipid ATPase (ALA) family members are expressed in pollen. Here we show that double knockout of ALA6 and ALA7 (ala6/7) results in siliques with a similar to 2-fold reduction in seed set with a high frequency of empty seed positions near the bottom. Seed set was reduced to near zero when plants were grown under a hot/cold temperature stress. Reciprocal crosses indicate that the ala6/7 reproductive deficiencies are due to a defect related to pollen transmission. In-vitro growth assays provide evidence that ala6/7 pollen tubes are short and slow, with similar to 2-fold reductions in both maximal growth rate and overall length relative to wild-type. Outcrosses show that when ala6/7 pollen are in competition with wild-type pollen, they have a near 0% success rate in fertilizing ovules near the bottom of the pistil, consistent with ala6/7 pollen having short and slow growth defects. The ala6/7 phenotypes were rescued by the expression of either an ALA6-YFP or GFP-ALA6 fusion protein, which showed localization to both the plasma membrane and highly-mobile endomembrane structures. A mass spectrometry analysis of mature pollen grains revealed significant differences between ala6/7 and wild-type, both in the relative abundance of lipid classes and in the average number of double bonds present in acyl side chains. A change in the properties of the ala6/7 plasma membrane was also indicated by a similar to 10-fold reduction of labeling by lipophilic FM-dyes relative to wild-type. Together, these results indicate that ALA6 and ALA7 provide redundant activities that function to directly or indirectly change the distribution and abundance of lipids in pollen, and support a model in which ALA6 and ALA7 are critical for pollen fitness under normal and temperature-stress conditions.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available