Ethylene perception modulates tomato pollen tube growth by altering calcium signaling and cell wall remodeling

In tomato, there are seven ethylene receptors, ETR1, ETR2, ETR3, ETR4, ETR5, ETR6, and ETR7. In our laboratory, we have ETR3, ETR4, and ETR7, loss-of-function single mutants, in this study we compare the pollen tube length of ETR mutant KO with WT and NR (never rip) gain of function mutant. We found the pollen tube length in ETR3, ETR4, and ETR7 (KO) was more than WT; on the other hand, NR was less than WT, and the treatment by ethylene (ET) increase the length of pollen tube in all ETRs KO and WT but not in NR. The treatment by MCP-1 decreases the pollen tube length slightly in WT, 20% in ETR (KO) and no effect in NR. In conclusion, our results suggest that ethylene receptors (ETRs) in the active state inhibit pollen tube growth; therefore the ethylene is an essential factor for male gametophyte growth.