Class I TCP Transcription Factors Target the Gibberellin Biosynthesis GeneGA20ox1and the Growth-Promoting GenesHBI1andPRE6during Thermomorphogenic Growth inArabidopsis

Abstract

Plants respond to a rise in ambient temperature by increasing the growth of petioles and hypocotyls. In this work, we show that Arabidopsis thaliana class I TEOSINTE BRANCHED 1, CYCLOIDEA, PCF (TCP) transcription factors TCP14 and TCP15 are required for optimal petiole and hypocotyl elongation under high ambient temperature. These TCPs influence the levels of the DELLA protein RGA and the expression of growth-related genes, which are induced in response to an increase in temperature. However, the class I TCPs are not required for the induction of the auxin biosynthesis gene YUCCA8 or for auxin-dependent gene expression responses. TCP15 directly targets the gibberellin biosynthesis gene GA20ox1 and the growth regulatory genes HBI1 and PRE6. Several of the genes regulated by TCP15 are also targets of the growth regulator PIF4 and show an enrichment of PIF4- and TCP-binding motifs in their promoters. PIF4 binding to GA20ox1 and HBI1 is enhanced in the presence of the TCPs, indicating that TCP14 and TCP15 directly participate in the induction of genes involved in gibberellin biosynthesis and cell expansion by high temperature functionally interacting with PIF4. In addition, overexpression of HBI1 rescues the growth defects of tcp14 tcp15 double mutants, suggesting that this gene is a major outcome of regulation by both class I TCPs during thermomorphogenesis.

Difference Between Day and Night Temperatures Affects Stem Elongation in Tomato (Solanum lycopersicum) Seedlings via Regulation of Gibberellin and Auxin Synthesis

“…GA20ox plays a key role in the GA biosynthesis pathway and affects bioactive GA content (Yamaguchi, 2008). In A. thaliana, the over-expression of GA20ox enhances hypocotyl elongation (Huang et al, 1998;Coles et al, 1999;Ferrero et al, 2019), and the expression of GA20ox (GA20ox1) is upregulated by high temperatures in hypocotyls (Stavang et al, 2009). Thus, it is suggested that SlGA20ox1 plays a key role in regulating stem elongation in tomato seedlings in response to different DIF conditions.…”

“…Previous studies have suggested that phytohormones are involved in regulating plant growth in response to temperature. Gibberellin (GA) is known to play a key role in stem elongation (Davière and Achard, 2013;Binenbaum et al, 2018;Ferrero et al, 2019). Indole-3-acetic acid (IAA), an auxin, also plays an important role in cell elongation in the hypocotyl, the epicotyl, and other organs (Leyser, 2018;Zhao, 2018).…”

Analysis of Evolution, Expression and Genetic Transformation of TCP Transcription Factors in Blueberry Reveal That VcTCP18 Negatively Regulates the Release of Flower Bud Dormancy

“…There are few studies on the functional information of Class I TCP members, which are involved in plant development, growth, and proliferation. For example, AtTCP14 and AtTCP15 regulate embryonic growth via the gibberellin signaling pathway during seed germination (Resentini et al, 2015), and AtTCP15 directly acts on GA20ox1, HBI1, and PRE6 to promote petiole growth and hypocotyl elongation (Ferrero et al, 2019). In Arabidopsis, a tcp23-knockout line has an early-flowering phenotype, while overexpression lines exhibit the reverse phenotype, which indicates that AtTCP23 participates in the regulation of flowering (Balsemao-Pires et al, 2013).…”

A mutation in CsHY2 encoding a phytochromobilin (PΦB) synthase leads to an elongated hypocotyl 1(elh1) phenotype in cucumber (Cucumis sativus L.)

“…For example, Zhou et al (2018) reported overexpression of TCP17 leads to a long hypocotyl phenotype in Arabidopsis. TCP14 and TCP15 are required for optimal elongation and for the appropriate gene expression responses to a group of auxin inducible genes and the GA biosynthetic gene GA20ox1 in hypocotyls of Arabidopsis (Ferrero et al 2019;Ferrero et al 2021). Based on the transcriptome data, combined the knowledge from scienti c literature, we speculate that the hypocotyl elongation in elh1 is mainly due to the interaction and cooperative regulation of phys, GA/Auxin, cell cell-elongation-related genes and these differential TFs.…”