Regulation of a Cytochrome P450 Gene CYP94B1 by WRKY33 Transcription Factor Controls Apoplastic Barrier Formation in Roots to Confer Salt Tolerance

Abstract

Salinity is an environmental stress that causes decline in crop yield. Avicennia officinalis and other mangroves have adaptations such as ultrafiltration at the roots aided by apoplastic cell-wall barriers to thrive in saline conditions. We studied a Cytochrome P450 gene from A. officinalis, AoCYP94B1, and its putative ortholog in Arabidopsis (Arabidopsis thaliana), AtCYP94B1, which are involved in apoplastic barrier formation. Both genes were induced by 30 minutes of salt treatment in the roots. Heterologous expression of AoCYP94B1 in the atcyp94b1 Arabidopsis mutant and wild-type rice (Oryza sativa) conferred increased NaCl tolerance to seedlings by enhancing root suberin deposition. Histochemical staining and GC-MS/MS quantification of suberin precursors confirmed the role of CYP94B1 in suberin biosynthesis. Using chromatin immunoprecipitation, yeast one-hybrid and luciferase assays, we identified AtWRKY33 as the upstream regulator of AtCYP94B1 in Arabidopsis. In addition, atwrky33 mutants exhibited reduced suberin and salt-sensitive phenotypes, which were rescued by expressing 35S::AtCYP94B1 in the atwrky33 background. This further confirmed that AtWRKY33-mediated regulation of AtCYP94B1 is part of the salt tolerance mechanism. Our findings may help efforts aimed at generating salt-tolerant crops.

Integrated transcriptome and proteome analysis reveals complex regulatory mechanism of cotton in response to salt stress

“…Among the transcription factors with the spatio-temporal expression patterns, about 32 and 49% were only differentially expressed at 3 h and 12 h after salt stress, respectively (Additional file 1: Figure S7a and b). Some of the transcription factors that were revealed to be responsive to salt stress previous studies were also detected in this study (Gao et al 2020;Krishnamurthy et al 2020;Xie et al 2010;Zhao et al 2019) (Additional file 1: Figure S7c).…”

Suberin plasticity to developmental and exogenous cues is regulated by a set of MYB transcription factors

“…4D). Among these elements, sodium was previously proposed to be directly affected by suberin and salt treatments were previously shown to induce suberization (6, 22, 43–45). This suggested that endodermal suberin induction in response to salt stress represents a protective mechanism against sodium entrance in plants.…”

WRKY9 transcription factor regulates cytochrome P450 genes CYP94B3 and CYP86B1, leading to increased root suberin and salt tolerance in Arabidopsis

“…So far, MYB39 and MYB41 are shown to regulate suberin formation (Cohen et al, 2020;Kosma et al, 2014). However, several CYP family genes are known to have the WRKY binding domains (W-box) in their promoter regions (Birkenbihl et al, 2017;Krishnamurthy et al, 2020;Xu et al, 2004). In a recent study, we showed that WRKY33 controls suberin formation by regulating CYP94B1 leading to enhanced salt tolerance of Arabidopsis and rice (Krishnamurthy et al, 2020).…”

“…Until recently, CYP94B family members were known to be involved in the initial ω-oxidation of jasmonic acid isoleucine (JA-Ile) to 12hydroxy jasmonic acid isoleucine (12OH-JA-Ile) affecting the JA signaling (Heitz et al, 2012;Kitaoka et al, 2011;Koo et al, 2011Koo et al, , 2014. However, in a recent study, we showed that CYP94B1 has a role in suberin biosynthesis (Krishnamurthy et al, 2020). Despite the increasing advances in understanding suberin biosynthesis and deposition, studies on the molecular mechanism regulating the genes involved in suberin formation are scarce.…”