Exocyst mutants suppress pollen tube growth and cell wall structural defects ofhydroxyproline O-arabinosyltransferasemutants
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Dokumenter
- Exocyst mutants suppress pollen tube growth and cell wall structural defects of hydroxyproline O-arabinosyltransferase mutants
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HYDROXYPROLINEO-ARABINOSYLTRANSFERASEs (HPATs) initiate a post-translational protein modification (Hyp-Ara) found abundantly on cell wall structural proteins. InArabidopsis thaliana,HPAT1andHPAT3are redundantly required for full pollen fertility. In addition to the lack of Hyp-Ara inhpat1/3pollen tubes (PTs), we also found broadly disrupted cell wall polymer distributions, particularly the conversion of the tip cell wall to a more shaft-like state. Mutant PTs were slow growing and prone to rupture and morphological irregularities. In a forward mutagenesis screen for suppressors of thehpat1/3low seed-set phenotype, we identified a missense mutation inexo70a2, a predicted member of the vesicle-tethering exocyst complex. The suppressed pollen had increased fertility, fewer morphological defects and partially rescued cell wall organization. A transcriptional null allele ofexo70a2also suppressed thehpat1/3fertility phenotype, as did mutants of core exocyst complex membersec15a, indicating that reduced exocyst function bypassed the PT requirement for Hyp-Ara. In a wild-type background,exo70a2reduced male transmission efficiency, lowered pollen germination frequency and slowed PT elongation. EXO70A2 also localized to the PT tip plasma membrane, consistent with a role in exocyst-mediated secretion. To monitor the trafficking of Hyp-Ara modified proteins, we generated an HPAT-targeted fluorescent secretion reporter. Reporter secretion was partially dependent onEXO70A2and was significantly increased inhpat1/3PTs compared with the wild type, but was reduced in the suppressedexo70a2 hpat1/3tubes.
Originalsprog | Engelsk |
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Tidsskrift | Plant Journal |
Vol/bind | 103 |
Udgave nummer | 4 |
Sider (fra-til) | 1399-1419 |
Antal sider | 21 |
ISSN | 0960-7412 |
DOI | |
Status | Udgivet - 2020 |
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ID: 249487803