Analysis of the tip-to-base gradient of CaM in pollen tube pulsant growth using in vivo CaM-GFP system.
Ca(2+)-CaM signaling is involved in pollen tube development. However, the distribution and function of CaM and the downstream components of Ca(2+)-CaM signal in pollen tube development still need more exploration. Here we obtained the CaM-GFP fusion protein transgenic line of Nicotiana tobacum SRI, which allowed us to monitor CaM distribution pattern in vivo and provided a useful tool to observe CaM response to various exogenous stimulations and afforded solid evidences of the essential functions of CaM in pollen tube growth. CaM-GFP fusion gene was constructed under the control of Lat52-7 pollen-specific promoter and transformed into Nicotiana tobacum SRI. High level of CaM-GFP fluorescence was detected at the germinal pores and the tip-to-base gradient of fluorescence was observed in developing pollen tubes. The distribution of CaM at apical dome had close relationship with the pulsant growth mode of pollen tubes: when CaM aggregated at the apical dome, pollen tubes stepped into growth state; When CaM showed non-polarized distribution, pollen tubes stopped growing. In addition, after affording exogenous Ca(2+), calmidazolium (antagonism of CaM) or Brefeldin A (an inhibitor of membrane trafficking), CaM turned to a uniform distribution at the apical dome and pollen tube growth was held back. Taken together, our results showed that CaM played a vital role in pollen tube elongation and growth rate, and the oscillation of tip-to-base gradient of CaM was required for the normal pulsant growth of pollen tube.
Shi
Ya-Ya
YY
Key Lab of MOE for Plant Developmental Biology, Wuhan University, 430072, Wuhan, People's Republic of China.
Tao
Wen-Jing
WJ
Liang
Shu-Ping
SP
Lü
Yingtang
Y
Zhang
Lei
L
D020126:Brefeldin A / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling; D002147:Calmodulin / Q000235:genetics / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D007093:Imidazoles / Q000494:pharmacology; D030821:Plants, Genetically Modified / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D053205:Pollen Tube / Q000254:growth & development* / Q000378:metabolism; D014026:Nicotiana / Q000235:genetics / Q000254:growth & development / Q000378:metabolism
D002147:Calmodulin; D007093:Imidazoles; D049452:Green Fluorescent Proteins; D020126:Brefeldin A; C031938:calmidazolium; D002118:Calcium