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
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
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DOI：
10.1101/2021.01.13.426551
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发表时间：
2021-01
期刊：
影响因子：
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通讯作者：
K. Kumari;Meng Zhao;Sebastian Britz;Christine Weiste;W. Dröge-Laser;C. Stigloher;R. Deeken;
中科院分区：
文献类型：
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作者：
K. Kumari;Meng Zhao;Sebastian Britz;Christine Weiste;W. Dröge-Laser;C. Stigloher;R. Deeken;
非特异性脂质转运蛋白（LTP）是陆地植物特有的富含半胱氨酸蛋白（CRP）大家族中的一个亚类。LTP具有疏水腔，使它们能够结合和稳定膜外的各种脂质分子。与N-末端信号肽的存在一致，分泌的LTP代表了植物细胞外基质中非常适合的移动的信号载体。因此，LTP目前被认为是介导脂质在膜/隔室之间的整体流动以及脂质屏障聚合物（包括角质和木栓质）的积聚的关键参与者。在这里，我们表明，花表达拟南芥AtLtpI.4（AtLTP 2）和AtLtpI.8（AtLTP 5），相互控制生长中的花粉管和胚珠在受精过程中的细胞间通讯。拟南芥突变体缺乏功能AtLtpI.4和AtLtpI.8表现出显着降低受精成功。异花授粉和细胞生物学分析表明，AtLtpI.4/I.8双突变体受损的花粉管导向胚珠。我们发现AtLtpI.4/I.8表型与胚珠发育过程中珠孔区域的异常胼胝质沉积相关，这表明两种LTP都代表了控制雌配子体中胼胝质稳态的联合信号通路的新参与者。
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 plant’s extracellular matrix. Thus, LTPs are currently considered as key players to mediate the bulk flow of 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.