Maize ZmBES1/BZR1-5 Decreases ABA Sensitivity and Confers Tolerance to Osmotic Stress in Transgenic Arabidopsis

Abstract

The BRI1-EMS suppressor 1 (BES1)/brassinazole-resistant 1 (BZR1) transcription factors, key components in the brassinosteroid signaling pathway, play pivotal roles in plant growth and development. However, the function of BES1/BZR1 in crops during stress response remains poorly understood. In the present study, we characterized ZmBES1/BZR1-5 from maize, which was localized to the nucleus and was responsive to abscisic acid (ABA), salt and drought stresses. Heterologous expression of ZmBES1/BZR1-5 in transgenic Arabidopsis resulted in decreased ABA sensitivity, facilitated shoot growth and root development, and enhanced salt and drought tolerance with lower malondialdehyde (MDA) content and relative electrolyte leakage (REL) under osmotic stress. The RNA sequencing (RNA-seq) analysis revealed that 84 common differentially expressed genes (DEGs) were regulated by ZmBES1/BZR1-5 in transgenic Arabidopsis. Subsequently, gene ontology and KEGG pathway enrichment analyses showed that the DEGs were enriched in response to stress, secondary metabolism and metabolic pathways. Furthermore, 30 DEGs were assigned to stress response and possessed 2–15 E-box elements in their promoters, which could be potentially recognized and bound by ZmBES1/BZR1-5. Taken together, our results reveal that the ZmBES1/BZR1-5 transcription factor positively regulates salt and drought tolerance by binding to E-box to induce the expression of downstream stress-related genes. Therefore, our study contributes to the better understanding of BES1/BZR1 function in the stress response of plants.

Analysis of Phytohormone Signal Transduction in Sophora alopecuroides under Salt Stress

“…Under stress, the positive regulator of the CK signaling pathway in Arabidopsis , ARR1/10/12 (B-ARR), can interact with SnRK2s to inhibit ABA signal transduction, while SnRK2s can phosphorylate ARR5 (A-ARR) to inhibit CK signaling [ 85 ]. Mutants of BR signal-responsive genes BSK5 and BIN2 in Arabidopsis are sensitive to ABA [ 86 , 87 ] and overexpression of ZmBES1/BZR1-5 in maize reduces the sensitivity to ABA [ 88 ]. Seed germination of saline-alkali land plants is dependent on the ratio of GA to ABA [ 89 ].…”

Genome-wide identification and characterization of the BES/BZR gene family in wheat and foxtail millet

“…The BES/BZR proteins are a large family of plant-specific transcription factors. As key components of the BR response pathway, BES/BZR proteins are not only involved in plant growth and developmental processes, but also respond to environmental stresses, such as drought, high salinity, and cold and heat stresses, in a variety of crops including Arabidopsis, Brassica rapa, Brassica napus, tomato, and maize [17,18,25,28,44]. Identification and characterization of BES/BZR transcription factors is therefore crucial to understand the molecular mechanism (s) underlying the environmental adaptions of plants to biotic and abiotic stresses.…”

“…Numerous studies have shown that BES/BZR genes respond to various signals, including BR, ABA, indoleacetic acid (IAA), SA, MeJA, GA, NaCl, and polyethylene glycol (PEG) [17,22,24,29,46]. In the current study, cis-acting element analysis revealed that the promoter of BES/BZR genes in wheat and foxtail millet contained some phytohormone-responsive elements, including those responding to ABA, MeJA, SA, GA, and auxin, and some stress-responsive elements, such as those responding to low-temperature, drought and high salinity (Fig.…”

“…Thirdly, increased BES1 levels enhance DNA binding of auxin-regulated transcription factor AUXIN RESPONSIVE FACTOR 5 (ARF5) to its target promoters, and BES1/BZR1 HOMO-LOG 4 (BEH4), which is a paralog of BES1, acts in partial redundancy with BES1 for the normal auxin response during growth of Arabidopsis seedlings [16]. A fourth example of the crosstalk is that the transcription factor ZmBES1/BZR1-5 from maize (Zea mays L.) decreases sensitivity to ABA and positively regulates salt and drought tolerance in transgenic Arabidopsis [17]. Furthermore, in response to pathogen infection or insect feeding, BES1 inhibits the jasmonate (JA)-inducible transcription of defensin genes PLANT DEFENSIN 1.2a (PDF1.2a) and PDF1.2b and biosynthesis of the JA-induced insect defense-related metabolite indolic glucosinolate, thus demonstrating the antagonism of BRs to JA-activated plant defense responses in Arabidopsis [18].…”

Antifreeze protein from Ammopiptanthus nanus functions in temperature-stress through domain A

“…As described by Sun et al 36 , T 1 seeds were surface-sterilized with 75% ethanol for 1 min and 10% NaClO for 10 min, and plated onto 1/2 MS plates with 50 mg/L kanamycin (Sigma, USA) for screening of transgenic plants, which were used to produce T 2 generation. The T 2 plants with 3:1 segregating-ratio to resistance/susceptibility of kanamycin were self-pollinated to generate T 3 .…”