The Banana MaWRKY18, MaWRKY45, MaWRKY60 and MaWRKY70 Genes Encode Functional Transcription Factors and Display Differential Expression in Response to Defense Phytohormones

Abstract

WRKY transcription factors (TFs) play key roles in plant defense responses through phytohormone signaling pathways. However, their functions in tropical fruit crops, especially in banana, remain largely unknown. Several WRKY genes from the model plants rice (OsWRKY45) and Arabidopsis (AtWRKY18, AtWRKY60, AtWRKY70) have shown to be attractive TFs for engineering disease resistance. In this study, we isolated four banana cDNAs (MaWRKY18, MaWRKY45, MaWRKY60, and MaWRKY70) with homology to these rice and ArabidopsisWRKY genes. The MaWRKY cDNAs were isolated from the wild banana Musa acuminata ssp. malaccensis, which is resistant to several diseases of this crop and is a progenitor of most banana cultivars. The deduced amino acid sequences of the four MaWRKY cDNAs revealed the presence of the conserved WRKY domain of ~60 amino acids and a zinc-finger motif at the N-terminus. Based on the number of WRKY repeats and the structure of the zinc-finger motif, MaWRKY18 and MaWRKY60 belong to group II of WRKY TFs, while MaWRKY45 and MaWRKY70 are members of group III. Their corresponding proteins were located in the nuclei of onion epidermal cells and were shown to be functional TFs in yeast cells. Moreover, expression analyses revealed that the majority of these MaWRKY genes were upregulated by salicylic acid (SA) or methyl jasmonate (MeJA) phytohormones, although the expression levels were relatively higher with MeJA treatment. The fact that most of these banana WRKY genes were upregulated by SA or MeJA, which are involved in systemic acquired resistance (SAR) or induced systemic resistance (ISR), respectively, make them interesting candidates for bioengineering broad-spectrum resistance in this crop.

Studying the Transcriptome Profiling of Banana Plantlets Exposed to Water Stress and the Alteration in Their Major Bioprocesses

“…Involvement of TF families, such as WRKY, MYB, bZIP, ABF, ABRE, and DRE, in response to abiotic stresses had been reported in bananas. García-Laynes et al (2022) identified the MaWRKY family genes from the wild banana Musa acuminata ssp. malaccensis, which is known as a progenitor of most banana cultivars, and resistant to several diseases and environmental disturbances.…”

Integrative systems biology analysis of barley transcriptome ─ hormonal signaling against biotic stress

“…In total, analyses revealed that most TF families such as AP2/ERF, bHLH, bZIP, WHIRLY1, and NF-Ys are not only implicated in the regulation network of SAR or ISR but also are involved in the regulation of SA and ET/JA cross-talks [ 115 ]. Transcriptional regulator NPR1 has been reported to be required for basal resistance toward biotrophic and hemibiotrophic pathogens, as well as the development of SAR and ISR [ 37 ].…”

Bacillus velezensis WB induces systemic resistance in watermelon against Fusarium wilt

“…51 NAC, WRKY and ERF play an important role in plant disease resistance by controlling the expression of genes involved in various cellular processes. [52][53][54] The overexpression of bZIP TFs (basic leucine zipper) can enhance salt tolerance in potato. 55 In the present study, 24 TFs were upregulated in the WF treatment, and 10 TFs were upregulated in the BF treatment, including MYB, NAC, bHLH, WRKY, ERF and bZIP (Figs 6 and S2), which suggested that B. velezensis WB induced systemic resistance to Fon by activating the expression of the above TFs.…”

“…MYB72 plays a central role in the regulation of ISR triggered by different root‐associated beneficial microbes 51 . NAC, WRKY and ERF play an important role in plant disease resistance by controlling the expression of genes involved in various cellular processes 52‐54 . The overexpression of bZIP TFs (basic leucine zipper) can enhance salt tolerance in potato 55 .…”