NtGNL1 plays an essential role in pollen tube tip growth and orientation likely via regulation of post-Golgi trafficking.
BACKGROUND
Tobacco GNOM LIKE 1 (NtGNL1), a new member of the Big/GBF family, is characterized by a sec 7 domain. Thus, we proposed that NtGNL1 may function in regulating pollen tube growth for vesicle trafficking.


RESULTS
To test this hypothesis, we used an RNAi technique to down-regulate NtGNL1 expression and found that pollen tube growth and orientation were clearly inhibited. Cytological observations revealed that both timing and behavior of endocytosis was disrupted, and endosome trafficking to prevacuolar compartments (PVC) or multivesicular bodies (MVB) was altered in pollen tube tips. Moreover, NtGNL1 seemed to partially overlap with Golgi bodies, but clearly colocalized with putative late endosome compartments. We also observed that in such pollen tubes, the Golgi apparatus disassembled and fused with the endoplasmic reticulum, indicating abnormal post-Golgi trafficking. During this process, actin organization was also remodeled.


CONCLUSIONS
Thus, we revealed that NtGNL1 is essential for pollen tube growth and orientation and it likely functions via stabilizing the structure of the Golgi apparatus and ensuring post-Golgi trafficking.
Liao
Fanglei
F
Key Laboratory of Ministry of Education, Plant Developmental Biology, College of Life Sciences, Wuhan University, Wuhan, China.
Wang
Lu
L
Yang
Li-Bo
LB
Peng
Xiongbo
X
Sun
Mengxiang
M
D000199:Actins / Q000378:metabolism; D003599:Cytoskeleton / Q000378:metabolism; D015536:Down-Regulation; D004705:Endocytosis / Q000502:physiology*; D006056:Golgi Apparatus / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000502:physiology*; D030821:Plants, Genetically Modified; D011058:Pollen; D034622:RNA Interference; D014026:Nicotiana / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism
D000199:Actins; D010940:Plant Proteins