Molecular characterization of the promoter of the stress-inducible ZmMYB30 gene in maize

Abstract

The ZmMYB30 is a member of the myeloblastosis (MYB) transcription factor superfamily, which has been shown to be a transcription regulator in abiotic stress tolerance in maize (Zea mays). To further identify the biological function of ZmMYB30 and reveal how its expression is induced in response to stress, we isolated the ZmMYB30 promoter and conducted a functional analysis. A 1461-bp promoter fragment was cloned and sequenced. Motif prediction using PlantCARE revealed several stress-responsive elements in the promoter sequence. Deletions in the promoter sequence affected the activity of the promoter and demonstrated that putative stress-responsive motifs, including TC-rich repeats (ATTCTCTAAC), abscisic acid responsive element (ABRE, ACGTG), and MYB binding site (MBS, CAACTG), played important roles in regulating the expression of ZmMYB30. Promoter β-glucuronidase (GUS) analysis also showed that GUS expression under the control of the ZmMYB30 promoter responded to drought and salinity. Many natural variations in the ZmMYB30 promoter sequence were found among 31 inbred maize lines, including 22 single nucleotide polymorphisms (SNPs), 17 insertion and deletion (InDels), and approximately 400-bp long deletions. The ZmMYB30 expression varied greatly among the different inbred lines. The long fragment deletion in the promoter region did not impair the ZmMYB30 expression, whereas SNP (-374) in the MBS motif in the 62R and LH82 lines greatly decreased the ZmMYB30 expression. A site-specific mutation in the MBS motif also decreased the expression of the reporter GUS gene driven by the ZmMYB30 promoter sequence. The expressions of three stress-responsive genes ZmSOS1, ZmSOS2, and ZmABF3 were found to be consistent with the ZmMYB30 expression. Our results provide new evidence to support the role of ZmMYB30 as an important regulator in maize stress tolerance.

Discovery of DNA polymorphisms via whole genome resequencing and their functional relevance in salinity stress response in chickpea

“…An uncharacterized rice gene ( Os06g44220 ) that showed expression only under salinity stress, especially in the tolerant genotype, was found to harbor SNPs in its promoter region (Lee et al, 2017). A SNP in the MYB‐binding site in the promoter region of ZmMYB30 was found to influence the expression of the stress‐responsive genes in maize (Luo et al, 2020). DNA polymorphisms located in the coding regions can be classified as synonymous, non‐synonymous, and large‐effect.…”

“…For example, genes encoding the MYB TF ( Ca_02593 ), the homeobox TF ( Ca_02586 ), and the F‐box protein ( Ca_12512 ) were included. SNPs in the promoter region of a Myb TF in maize ( ZmMYB30 ) determined the expression of the stress‐responsive genes (Luo et al, 2020). The role of the rice OsHOX22 and OsHOX24 homeobox genes in the salinity stress response has been suggested (Bhattacharjee et al, 2016).…”

“…DNA polymorphisms, depending on their genomic location, may govern phenotypic plasticity and agronomic traits, including salinity stress responses (Lee et al, 2017; Luo et al, 2020; Qi et al, 2014). The advancement of high‐throughput sequencing technologies along with the availability of reference genome sequences of chickpea (Jain et al, 2013; Varshney et al, 2013) have provided excellent opportunities to perform large‐scale genotyping at affordable costs.…”

miR166h Directed Cleavage of Target Upon PGPR Inoculation Under Drought Stress and Tissue-Specific Expression Analysis Under Abiotic Stresses in Chickpea.

“…Promoter analysis of Oryza sativa lectin receptor-like kinases (LecRLKs) indicated the involvement of various cis-regulatory genes including TC-rich repeats under biotic stress (Passricha et al 2017). ZmMYB30 of Zea mays is also enriched with TC-rich repeats in its promoter and has roles in terms of salinity stress (Luo et al 2020). PDI gene family in Solanum lycopersicumalso has TC-rich repeats in promoter pointing their role towards the abiotic stress mitigation (Wai et al 2021).…”

Genome‐wide discovery ofDNApolymorphisms via resequencing of chickpea cultivars with contrasting response to drought stress

“…For instance, DNA polymorphisms in promoter region of HSP70 differentiated heat stress sensitive and tolerant genotypes in Paralichthys olivaceus (Qi et al, 2014). A SNP in the MYB-binding motif greatly reduced the expression of the underlying gene under drought stress in maize (Luo et al, 2020). Likewise, DNA polymorphisms in TFBSs have been implicated in several human diseases (Buroker, 2016).…”