DREB1 and DREB2 Genes in Garlic (Allium sativum L.): Genome-Wide Identification, Characterization, and Stress Response

Abstract

Dehydration-responsive element-binding (DREB) transcription factors (TFs) of the A1 and A2 subfamilies involved in plant stress responses have not yet been reported in Allium species. In this study, we used bioinformatics and comparative transcriptomics to identify and characterize DREB A1 and A2 genes redundant in garlic (Allium sativum L.) and analyze their expression in A. sativum cultivars differing in the sensitivity to cold and Fusarium infection. Eight A1 (AsaDREB1.1–1.8) and eight A2 (AsaDREB2.1–2.8) genes were identified. AsaDREB1.1–1.8 genes located in tandem on chromosome 1 had similar expression patterns, suggesting functional redundancy. AsaDREB2.1–2.8 were scattered on different chromosomes and had organ- and genotype-specific expressions. AsaDREB1 and AsaDREB2 promoters contained 7 and 9 hormone- and stress-responsive cis-regulatory elements, respectively, and 13 sites associated with TF binding and plant development. In both Fusarium-resistant and -sensitive cultivars, fungal infection upregulated the AsaDREB1.1–1.5, 1.8, 2.2, 2.6, and 2.8 genes and downregulated AsaDREB2.5, but the magnitude of response depended on the infection susceptibility of the cultivar. Cold exposure strongly upregulated the AsaDREB1 genes, but downregulated most AsaDREB2 genes. Our results provide the foundation for further functional analysis of the DREB TFs in Allium crops and could contribute to the breeding of stress-tolerant varieties.

Factors affecting the infection by Fusarium oxysporum and F. proliferatum and the progress of garlic clove rot disease during storage

“…These findings could be interpreted in light of similar other results previously reported by Shalaby et al (2012), Moharam et al (2013), El-Marzoky, Hanan and Shaban (2014), Elshahawy et al (2017), andAhmed, Naglaa et al (2022). In addition, several investigators worldwide have reported other resistant and susceptible garlic cultivars and varieties to clove/bulb rot disease caused by F. oxysporum and F. proliferatum and/or other garlic diseases caused by pathogenic fungi (Shalaby et al, 2012;Palmero et al, 2013;Ignjatov et al, 2018;Jannatun et al, 2020;Filyushin et al, 2021;Anisimova, Olga et al, 2021). Thus, a closely established relationship exists between the presence of the pathogen F. oxysporum and F. proliferatum in the garlic bulb at harvest and the incidence and progress of cloves rot disease in storage.…”

“…Thus, a closely established relationship exists between the presence of the pathogen F. oxysporum and F. proliferatum in the garlic bulb at harvest and the incidence and progress of cloves rot disease in storage. Differences in susceptibility of garlic cultivars to F. oxysporum and F. proliferatum mainly due to genetic factors (Shalaby et al, 2012;Palmero et al, 2013;El-Marzoky, Hanan and Shaban, 2014;Elshahawy et al, 2017;Ignjatov et al, 2018;Jannatun et al, 2020;Filyushin et al, 2021;Anisimova, Olga et al, 2021). In this study, out of storage temperatures affecting the development of cloves rot disease of garlic Balady (the highest susceptible) and Seds 40 (the least susceptible) cultivars after 30, 60, and 90 days of storage, 30 °C was the most affecting ones and gradually increased disease severity index of cloves rot caused by both fungi on stored bulbs of both garlic cultivars after 90 days of storage, followed by 25 °C.…”

AnDREB5.1, a A5 group DREB gene from desert shrub Ammopiptanthus nanus, confers osmotic and cold stress tolerances in transgenic tobacco

“…Several DREB A2 TFs were cloned from different angiosperm species, including dicotyledonous plants like sunflowers (Najafi et al, 2018) and grass species like rice (Herath et al, 2016), wheat (Egawa et al, 2006), barley (Kovalchuk et al, 2013), and corn (Filyushin et al, 2022). While most reported DREB2 genes are activated under drought or heat stress, DREB2 genes from grasses were also upregulated under low‐temperature stress (Mizoi et al, 2012; Filyushin et al, 2023; Nguyen et al, 2017).…”