Female gametophyte expressed Arabidopsis thaliana lipid transfer proteins AtLtpI.4 and AtLtpI.8 provide a link between callose homeostasis, pollen tube guidance, and fertilization success [article]

Khushbu Kumari, Meng Zhao, Sebastian Britz, Christine Weiste, Wolfgang Droege-Laser, Christian Stigloher, Rosalia Deeken, Dirk Becker
2021 bioRxiv   pre-print
Non-specific lipid transfer proteins (LTPs) represent a sub-class among the large family of Cysteine-rich proteins (CRPs) specific to land plants. LTPs possess a hydrophobic cavity, enabling them to bind and stabilize a variety of lipid molecules outside membranes. In line with the existence of an N-terminal signal peptide, secreted LTPs represent a well-suited mobile signal carrier in the plants extracellular matrix. Thus, LTPs are currently considered as key players to mediate the bulk flow
more » ... lipids between membranes/compartments as well as the buildup of lipid barrier polymers including cutin and suberin. Here, we show that floral expressed Arabidopsis thaliana AtLtpI.4 (AtLTP2) and AtLtpI.8 (AtLTP5), mutually control cell-cell communication between growing pollen tubes and ovules during fertilization. Arabidopsis mutants lacking functional AtLtpI.4 and AtLtpI.8 exhibit significantly reduced fertilization success. Cross-pollination and cell biological analyses revealed that AtLtpI.4/I.8 double mutants are impaired in pollen tube guidance towards ovules. Our finding that the AtLtpI.4/I.8 phenotype correlates with aberrant callose depositions in the micropylar region during ovule development suggests that both LTPs represent novel players of a joint signaling pathway that controls callose homeostasis in the female gametophyte.
doi:10.1101/2021.01.13.426551 fatcat:6gkvr4h5f5c7nozl76qtdfisg4