17456
Potassium ( K ( + ) ) influx into pollen tubes via K ( + ) transporters is essential for pollen tube growth ; however , the mechanism by which K ( + ) transporters are regulated in pollen tubes remains unknown .
 Chemical: Potassium; Chemical: K ( + ); Chemical: K ( + ); Chemical: K ( + )
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 Chemical: Potassium; Chemical: K ( + ); Chemical: K ( + ); Chemical: K ( + )