MdMYB46 could enhance salt and osmotic stress tolerance in apple by directly activating stress‐responsive signals

Summary To expand the cultivation area of apple ( Malus×domestica Borkh.) and select resistant varieties by genetic engineering, it is necessary to clarify the mechanism of salt and osmotic stress tolerance in apple. The Md MYB 46 transcription factor was identified, and the stress treatment test of Md MYB 46 ‐overexpressing and Md MYB 46 ‐ RNA i apple lines indicated that Md MYB 46 could enhance the salt and osmotic stress tolerance in apple. In transgenic Arabidopsis and apple, Md MYB 46 promoted the biosynthesis of secondary cell wall and deposition of lignin by directly binding to the promoter of lignin biosynthesis‐related genes. To explore whether Md MYB 46 could coordinate stress signal transduction pathways to cooperate with the formation of secondary walls to enhance the stress tolerance of plants, Md ABRE 1A , Md DREB 2A and dehydration‐responsive genes Md RD 22 and Md RD 29A were screened out for their positive correlation with osmotic stress, salt stress and the transcriptional level of Md MYB 46 . The further verification test demonstrated that Md MYB 46 could activate their transcription by directly binding to the promoters of these genes. The above results indicate that Md MYB 46 could enhance the salt and osmotic stress tolerance in apple not only by activating secondary cell wall biosynthesis pathways, but also by directly activating stress‐responsive signals.