Isolation of the ZmERS4 Gene From Maize and Its Functional Analysis in Transgenic Plants

Abstract

A gene encoding a protein similar to ethylene receptor was isolated from maize (Zea mays L.), which was named as ZmERS4.The gene was 1,905 bp in length with an open reading frame that encoded a protein consisting of 634 amino acids. The homologous analysis showed that ZmERS4 shared high similarity with the ethylene receptor protein, OsERS1, from rice (Oryza sativa L.). ZmERS4 grouped into the ETR1 subfamily of ethylene receptors based on its conserved domain and phylogenetic status. Tissue-specific and induced expression analyses indicated that ZmERS4 was differentially expressed in maize tissues, predominantly in the stems and leaves, and was induced by salicylic acid (SA). Overexpression of ZmERS4 in Arabidopsis improved resistance against the bacterial pathogen, PstDC3000, by inducing the expression of SA signaling-related genes. Moreover, treatment with flg22 induced the expression of the defense-related gene, PR1, in maize protoplasts that transiently expressed ZmERS4. Furthermore, the ultra-high-performance liquid chromatography (UPLC) analysis showed that the SA contents in ZmERS4-overexpressing Arabidopsis lines were significantly higher than the control lines. Additionally, the improved resistance of ZmERS4-overexpressing Arabidopsis against PstDC3000 was blocked after pretreatment with the SA biosynthetic inhibitor, ABT. Based on the collective findings, we hypothesize that ZmERS4 plays an important role in disease resistance through SA-mediated signaling pathways.

ZmGLP1, a Germin-like Protein from Maize, Plays an Important Role in the Regulation of Pathogen Resistance

“…Then, using MEGA v7.0 software, the obtained sequences were clustered by the neighbor-joining (NJ) method, and the constructed phylogenetic tree was optimized using the ITOL website (https:// itol.embl.de/, accessed on 20 January 2021). The data required for drawing a heat map of the tissue-specific expression of ZmGLP1 were obtained from the Corn database (http: //www.plexdb.org/plex.php?database=Corn, accessed on 20 January 2021); a heat map was drawn following previously described methods [20,21].…”

“…Then, plasmid correctness was confirmed by enzyme digestion analysis and sequencing. ZmGLP1 transgenic Arabidopsis was generated by Agrobacterium-mediated genetic transformation [21]. Transgenic T3 homozygous Arabidopsis was used in the follow-up experiments.…”

“…Analyses of ZmGLP1 expression induced by biotic stress and hormones and the tissue-specific expression of ZmGLP1 were conducted following previously described methods [21]. Plants at the three-leaf stage were treated with salicylic acid (SA) (1 mM), jasmonic acid (JA) (50 µM), or ethephon (ET) (1 mM) and infected with Curvularia lunata (1 × 10 5 CFU/mL), Bipolaris maydis (1 × 10 5 CFU/mL), or Pantoea stewartii (1 × 10 6 CFU/mL).…”