Several NF-induced processes, such as: a transient increase of reactive oxygen species (ROS) production; activation of phospholipase C (PLC) and PLD; and prolonged oscillations of (peri)nuclear [Ca2+] are implicated in switching on the symbiotic programme [63]–[69], whereas a Ca2+ influx is postulated to act as a signal for infection thread formation [70]. Here, GPLD1 is linked to infection.