Ethylene Biosynthesis, Signaling, and Crosstalk with Other Hormones in Rice

Abstract

Ethylene is a multifunctional hormone involved in regulating plant development, conferring adaptive growth, and responding to biotic/abiotic stresses. Rice is a monocotyledonous crop and usually grows in water environments with some unique features. Here, ethylene biosynthesis, signaling, and interaction with other hormones in rice are summarized and discussed in comparison to those from Arabidopsis and/or other plants. Ethylene biosynthesis in rice responds to internal developmental signals and external stimuli such as grain filling, leaf senescence, darkness, mechanical resistance, hypoxia, chill, salt stress, and metal ions. Gene expression regulation in ethylene biosynthesis pathway shows time and spatial specificity. Through mutant analysis and homologue analysis, an ethylene signaling pathway is proposed in rice, and conserved components/mechanisms as well as new components/mechanisms are identified. Ethylene widely interacts with other hormones in rice by synergy or antagonism. Normally, auxin and gibberellin are synergistic with ethylene to regulate growth, while abscisic acid is antagonistic to ethylene in reproductive growth and various stress response. Ethylene diminishes jasmonic acid–inhibited elongation growth, but synergistically promotes leaf senescence. All these studies provide novel insights into the ethylene biology in rice and other crops, and may facilitate breeding for cultivars with better agronomic traits.

Ethylene signaling in rice and Arabidopsis: New regulators and mechanisms

“…Compared with the control rice cultivar, single loss‐of‐function mutants of ethylene receptors, that is, Osers1 , Osers2 , Osetr2 , and Osetr3 , exhibited mild ethylene hypersensitivity in etiolated seedlings but showed largely normal growth in the field (Wuriyanghan et al, 2009; Ma et al, 2013; Yin et al, 2015). Compared with the control, the homozygous Osers1 Osers2 double mutants showed severe growth defects, including reduced height and increased tiller numbers, and produced only a few seeds that could germinate but failed to survive later (Zhou et al, 2019), suggesting that the subfamily I receptors may play vital roles in rice growth and development. Interestingly, while OsERS2 has been found to localize to the ER membrane (Zhao et al, 2020b), OsERS1 mainly localizes to the plasma membrane (Yu et al, 2017a), indicating that the two subfamily I receptor members may have functional differentiations.…”

“…As a multifunctional hormone, ethylene has been proven to interact with several plant hormones to function. A recent comprehensive summary of the crosstalk between ethylene and other plant hormones in rice in last year's issue of Small Methods could be read in parallel with our review (Zhou et al, 2019). Here, we mainly discuss the crosstalk between ethylene and other hormones in regulating the “triple response” and “double response” in Arabidopsis and rice, respectively.…”

“…Auxin has been shown to stimulate the elongation of apical coleoptile segments from rice etiolated seedlings in an ethylene‐dependent manner (Imaseki and Pjon, 1970). Moreover, it has been proposed that ethylene and auxin may function additively and cooperatively to regulate coleoptile elongation (Zhou et al, 2019).…”

The GDSL Lipase MHZ11 Modulates Ethylene Signaling in Rice Roots

“…Rice mhz11 was identified in a genetic screen for rice ethylene-response mutants from our ethylmethanesulfonate (EMS) mutant populations (Zhou et al, 2019). In air, dark-grown seedlings of wild type (WT) and mhz11 were similar in coleoptile and root growth.…”

“…This function is likely achieved by affecting sterol homeostasis. Our study discovers a previously unidentified mechanism and provides insights into the understanding of how OsCTR2 is regulated during ethylene signal transduction.METHODSPlant materials and growth conditionsmhz11 and Osers2 d mutants were identified in our genetic screen for rice (Oryza sativa) ethylene-response mutants from our EMS-induced mutant pools of Nipponbare rice(Zhou et al, 2019). Osers2 d harbors a dominant gain-of-function…”