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In plant, APETALA2/ethylene‐responsive factor (AP2/ERF)‐domain transcription factors are important in regulating abiotic stress tolerance. In this study, ZmEREB57 encoding a AP2/ERF transcription factor was identified and its function was investigated in maize. ZmEREB57 is a nuclear protein with transactivation activity induced by several abiotic stress types. Furthermore, two CRISPR/Cas9 knockout lines of ZmEREB57 showed enhanced sensitivity to saline conditions, whereas the overexpression of ZmEREB57 increased salt tolerance in maize and Arabidopsis. DNA affinity purification sequencing (DAP‐Seq) analysis revealed that ZmEREB57 notably regulates target genes by binding to promoters containing an O‐box‐like motif (CCGGCC). ZmEREB57 directly binds to the promoter of ZmAOC2 involved in the synthesis of 12‐oxo‐phytodienoic acid (OPDA) and jasmonic acid (JA). Transcriptome analysis revealed that several genes involved in regulating stress and redox homeostasis showed differential expression patterns in OPDA‐ and JA‐treated maize seedlings exposed to salt stress compared to those treated with salt stress alone. Analysis of mutants deficient in the biosynthesis of OPDA and JA revealed that OPDA functions as a signalling molecule in the salt response. Our results indicate that ZmEREB57 involves in salt tolerance by regulating OPDA and JA signalling and confirm early observations that OPDA signalling functions independently of JA signalling. SUMMARY STATEMENT: As an important cereal crop worldwide, however, the yield and quality of maize are severely affected by salt stress. This study identified that ZmEREB57, a AP2/ERF transcription factor, contributes to salt tolerance in maize. The ZmEREB57‐mediated salt stress response can be achieved by binding to the ZmAOC2 promoter, which is a positive regulator of OPDA biosynthesis. Although as being a precursor for JA synthesis, OPDA functions independently of JA as a signalling molecule in the salt response. [ABSTRACT FROM AUTHOR]

Wheat plants are ubiquitously simultaneously exposed to salinity and limited iron availability caused by soil saline‐alkalisation. Through this study, we found that both low Fe and NaCl severely inhibited the growth of seminal roots in wheat seedlings; however, sufficient Fe caused greater growth cessation of seminal roots than low Fe under salt stress. Low Fe improved the root meristematic division activity, not altering the mature cell sizes compared with sufficient Fe under salt stress. Foliar Fe spray and split‐root experiments showed that low Fe‐alleviating the salinity‐induced growth cessation of seminal roots was dependent on local low Fe signals in the roots. Ionomics combined with TEM/X‐ray few differences in the root Na+ uptake and vacuolar Na+ sequestration between two Fe levels under salt stress. Phytohormone profiling and metabolomics revealed salinity‐induced overaccumulation of ACC/ethylene and tryptophan/auxin in the roots under sufficient Fe than under low Fe. Differential gene expression, pharmacological inhibitor addition and the root growth performance of transgenic wheat plants revealed that the rootward auxin efflux and was responsible for the low Fe‐mediated amelioration of the salinity‐induced growth cessation of seminal roots. Our findings will provide novel insights into the modulation of crop root growth under salt stress. Summary statement: We found that low Fe ameliorated the salinity‐induced growth cessation of wheat seminal roots, and our findings will provide novel insights into the understanding of Fe involved nutrient interactions and the modulation of crop root growth under salt stress. [ABSTRACT FROM AUTHOR]