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Two Membrane-Anchored Aspartic Proteases Contribute to Pollen and Ovule Development
Hui Gao1,2, Yinghui Zhang1,2, Wanlei Wang1,2
1Hebei Key Laboratory of Molecular and Cellular Biology and Key Laboratory of Molecular and Cellular Biology of the Ministry of Education, College of Life Science, Hebei Normal University, Shijia Zhuang, Hebei 050024, People's Republic of China (H.G., Y.Z., W.W., K.Z., C.L., L.B., R.L., Y.G.); and.
Plant Physiology
|November 23, 2016
Summary
Two Arabidopsis aspartic proteases, A36 and A39, are crucial for plant reproduction. Mutations in these genes lead to reduced pollen activity and compromised pollen tube guidance, suggesting a role in programmed cell death and cell wall modification.
Area of Science:
- Plant Biology
- Molecular Genetics
- Enzymology
Background:
- Aspartic proteases are essential proteolytic enzymes involved in various cellular processes.
- Plants have a diverse family of aspartic proteases, but their functions remain largely uncharacterized.
- Glycosylphosphatidylinositol (GPI)-anchored proteins play roles in cell wall structure and signaling.
Purpose of the Study:
- To characterize the function of two novel Arabidopsis aspartic protease genes, A36 and A39, in plant reproduction.
- To investigate the role of these GPI-anchored proteases in pollen viability and pollen tube guidance.
- To explore the molecular mechanisms underlying the reproductive defects observed in mutant plants.
Main Methods:
- Gene characterization of A36 and A39 in Arabidopsis thaliana.
- Analysis of pollen activity and viability in a36 and a39 mutants using microscopy and staining techniques.
- Localization studies of A36 and A39 proteins using green fluorescent protein (GFP) tagging.
- Analysis of cell wall composition in pollen tubes of mutant plants.
Main Results:
- Mutants lacking A36 and A39 exhibited significantly reduced pollen activity and viability, with evidence of apoptosis-like programmed cell death.
- Female gamete degeneration was observed in the mutants.
- Pollen tube guidance to the micropyle was severely impaired in a36 a39 mutants.
- A36 and A39 proteins localized to the plasma membrane and colocalized with a known GPI-anchored protein.
- Increased abundance of highly methylesterified homogalacturonans and xyloglucans was found in the apical pollen tube wall of mutants.
Conclusions:
- A36 and A39 are essential GPI-anchored aspartic proteases involved in Arabidopsis reproduction.
- These proteases play critical roles in pollen viability, programmed cell death regulation, and pollen tube guidance.
- A36 and A39 influence pollen tube wall composition, affecting cell wall integrity and guidance mechanisms.
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