Warm Temperature Promotes Shoot Regeneration inArabidopsis thaliana

Abstract

Many plants are able to regenerate upon cutting, and this process can be enhanced in vitro by incubating explants on hormone-supplemented media. While such protocols have been used for decades, little is known about the molecular details of how incubation conditions influence their efficiency. In this study, we find that warm temperature promotes both callus formation and shoot regeneration in Arabidopsis thaliana. We show that such an increase in shoot regenerative capacity at higher temperatures correlates with the enhanced expression of several regeneration-associated genes, such as CUP-SHAPED COTYLEDON 1 (CUC1) encoding a transcription factor involved in shoot meristem formation and YUCCAs (YUCs) encoding auxin biosynthesis enzymes. ChIP-sequencing analyses further reveal that the histone variant H2A.Z is enriched on these loci at 17°C, while its occupancy is reduced by an increase in ambient temperature to 27°C. Moreover, we provide genetic evidence to demonstrate that H2A.Z acts as a repressor of de novo shoot organogenesis, since H2A.Z-depleted mutants display enhanced shoot regeneration. This study thus uncovers a new chromatin-based mechanism that influences hormone-induced regeneration and additionally highlights incubation temperature as a key parameter for optimizing in vitro tissue culture.

WUSCHEL-RELATED HOMEOBOX 13 suppresses de novo shoot regeneration via cell fate control of pluripotent callus

“…Loss-of-function mutation of DNA METHYLTRANSFERASE 1 ( MET1 ) or POLYCOMB REPRESSIVE COMPLEX 2 ( PRC2 ) leads to enhanced shoot regeneration, suggesting that erasing these repressive marks facilitates de novo SAM establishment ( 12 , 7 ). Similarly, a repressive histone variant H2A.Z restricts regeneration efficiency, which seems to mediate temperature responses ( 13 ). A SUMO E3 ligase, SAP AND MIZ1 DOMAIN-CONTAINING LIGASE1 (SIZ1), negatively regulates de novo shoot formation, potentially through suppressing the stress response ( 14 ).…”

A network of CLAVATA receptors buffers auxin-dependent meristem maintenance

“…PIT phenotypes overlap with crn shoot and primordia defects to a degree, but key differences exist suggesting they are not equivalent. Despite this, PIT is sensitized to temperature and auxin levels, like other CLV IM processes, reminiscent of heat and YUC impacts on de novo shoot regeneration 55 . Interestingly, our data suggest heat and loss of ELF3 do not appear entirely equivalent.…”

The dynamics of chromatin states mediated by epigenetic modifications during somatic cell reprogramming

“…Indeed, H3.15 can replace canonical H3s and reduce the deposition of H3K27me3 catalyzed by PRC2, resulting in transcriptional derepression of downstream genes such as WOX11 and LBD18 ( Yan et al, 2020 ). Another histone variant, H2A.Z, acts as a repressor of SCR in Arabidopsis, as a double mutant lacking two HISTONE H2A.Z variant genes, hta9 hta11 , displayed enhanced shoot regeneration ( Lambolez et al, 2022 ). Some genes involved in organ regeneration or auxin biosynthesis, such as YUC genes, are upregulated by the reduction of H2A.Z that occurs when plants are exposed to high temperature (27 °C) ( Lambolez et al, 2022 ).…”

“…Another histone variant, H2A.Z, acts as a repressor of SCR in Arabidopsis, as a double mutant lacking two HISTONE H2A.Z variant genes, hta9 hta11 , displayed enhanced shoot regeneration ( Lambolez et al, 2022 ). Some genes involved in organ regeneration or auxin biosynthesis, such as YUC genes, are upregulated by the reduction of H2A.Z that occurs when plants are exposed to high temperature (27 °C) ( Lambolez et al, 2022 ). Furthermore, H2A.Z is highly conserved in eukaryotes and its abundance is enriched near the TSS of genes with high transcriptional activity ( Dong et al, 2016 ; Zhang et al, 2017 ).…”