Ethylene signaling in rice and Arabidopsis: New regulators and mechanisms

Abstract

Ethylene is a gaseous hormone which plays important roles in both plant growth and development and stress responses. Based on studies in the dicot model plant species Arabidopsis, a linear ethylene signaling pathway has been established, according to which ethylene is perceived by ethylene receptors and transduced through CONSTITUTIVE TRIPLE RESPONSE 1 (CTR1) and ETHYLENE‐INSENSITIVE 2 (EIN2) to activate transcriptional reprogramming. In addition to this canonical signaling pathway, an alternative ethylene receptor‐mediated phosphor‐relay pathway has also been proposed to participate in ethylene signaling. In contrast to Arabidopsis, rice, a monocot, grows in semiaquatic environments and has a distinct plant structure. Several novel regulators and/or mechanisms of the rice ethylene signaling pathway have recently been identified, indicating that the ethylene signaling pathway in rice has its own unique features. In this review, we summarize the latest progress and compare the conserved and divergent aspects of the ethylene signaling pathway between Arabidopsis and rice. The crosstalk between ethylene and other plant hormones is also reviewed. Finally, we discuss how ethylene regulates plant growth, stress responses and agronomic traits. These analyses should help expand our knowledge of the ethylene signaling mechanism and could further be applied for agricultural purposes.

Physcomitrium patens Infection by Colletotrichum gloeosporioides: Understanding the Fungal–Bryophyte Interaction by Microscopy, Phenomics and RNA Sequencing

“…nramp genes participate in the ethylene-defense response and were also upregulated ( Figure 4 B). NRAMP domain-containing proteins have been described as an evolutionary conserved ethylene signaling components and nramp genes are present in genomes of aquatic ancestors of land plants [ 94 ]. On the other hand, we found overexpression of the mlp gene, which has been recently related to increased drought tolerance and transcriptional level of abscisic acid synthetic genes in tobacco.…”

OsWAK112, A Wall-Associated Kinase, Negatively Regulates Salt Stress Responses by Inhibiting Ethylene Production

“…Ethylene is a stress hormone closely related with salt stress ( Riyazuddin et al, 2020 ). In plants, ethylene is biosynthesized from S-adenosyl-L-methionine (SAM; Zhao et al, 2021a ), which is synthesized from l-methionine and ATP catalyzed by SAMSs. To explore the mechanism underlying the function of OsWAK112 in plant salt responses, the ethylene content was measured in Jap and OsWAK112OE plants.…”

“…Ethylene homeostasis is tightly controlled to maintain its dual functions in growth inhibition and growth stimulation. Under normal conditions, the ethylene concentration is low and only increases dramatically at defined developmental stages, such as fruit ripening ( Zhao et al, 2021a ). A variety of environmental stimuli, including salt stress, can also induce ethylene production ( Nascimento et al, 2018 ; Riyazuddin et al, 2020 ), in which the ACC synthase-induced conversion of SAM to ACC is a key step.…”

“…Among the nine well-characterized plant hormones, ethylene, gibberellin, jasmonic acid, and cytokinins are able to be regulated by salt stress ( Yu et al, 2020 ). Numerous studies have shown that ethylene plays a crucial role in the regulation of diverse stress responses, including it to salt stress ( Riyazuddin et al, 2020 ; Zhao et al, 2021a ). In plants, ethylene is biosynthesized from S-adenosyl-L-methionine (SAM), which is synthesized from l-methionine to ATP catalyzed by S-adenosyl-L-methionine synthetases (SAMSs).…”

Essential Roles of the Linker Sequence Between Tetratricopeptide Repeat Motifs of Ethylene Overproduction 1 in Ethylene Biosynthesis

“…Constitutive triple response 1 (CTR1), a serine/threonine Raf-like kinase, is a negative regulator in ethylene signaling as it can bind to the receptors (Mayerhofer et al, 2012;Yasumura et al, 2015). The activation (receptor bound form) and inactivation (receptor released form) of CTR1 is controlled by the absence or presence of ethylene, respectively, which further switches the phosphorylation and non-phosphorylation states of the positive regulator EIN2 (Zhao et al, 2021). In the absence of ethylene, CTR1 activation leads to the phosphorylation of the C-terminal domain of EIN2, which targets the EIN2 for degradation, leading to the repression of ethylene responses in plants.…”