*Editorial* **Cell Signaling in Model Plants**

**Jen-Tsung Chen 1,\* and Parviz Heidari 2**


Received: 20 August 2020; Accepted: 20 August 2020; Published: 23 August 2020

Plants as sessile organisms are not able to move and must cope with adverse environmental conditions and stresses such as extreme temperatures, drought, high soil salinity, oxidative stress, pathogen attack, and so on. To respond in an appropriate manner to a specific environmental stimulus, plants possess signal transduction pathways, which are complex networks of interactions involving signal elements transmitting through the plant cell. In fact, cell signaling a ffects virtually every aspect of plant cell structure and function. For building elegant, complicated, and interconnected regulating networks, a huge number of components are involved, including receptors, secondary messengers, protein kinases, transcription factors, reactive oxygen species (ROS), and plant hormones that regulate or stimulate other components. Therefore, to unveil a global picture of plant cell signaling networks and underlying master regulators and machinery remains a challenge for researchers. For enriching our understanding of plant cell signaling with the assistance of modern molecular tools, this Special Issue "Cell Signaling in Model Plants" collects recent innovative original research and reviews, with an emphasis on the studies using model plants and crops. A total of 14 publications were published, which can be divided into five subtopics, as described below.

#### **1. Arabidopsis Thaliana Transmembrane Receptor-Like Kinases (RLKs)**

Transmembrane receptor-like kinases (RLKs) are conserved protein kinases that play critical roles in transducing the signal from the outside to the inside of plant cells, particularly to the nucleus. Jose et al. refined the recent advances of transmembrane RLKs in *A. thaliana* to unveil how stress responses as well as plant development are regulated by signaling pathways related to di fferent groups of RLKs [1].

#### **2. Functional Analysis of Signaling Components**

#### *2.1. Flowering Locus C (FLC) Homologs*

To reveal the underlying mechanisms controlling the annual flowering of fruit trees, Kagaya et al. analyzed the function of *FLOWERING LOCUS C* (*FLC*) homologs in apple [2]. They declared that homologs of *FLC* might be involved in flowering and associated with juvenility.
