Abstract
BackgroundThe MYB transcription factor family is one of the largest transcriptional factor families in plants and plays a multifaceted role in plant growth and development. However, MYB transcription factors involved in pathogen resistance in apple remain poorly understood.ResultsWe identified a new MYB family member from apple, and named it MdMYB30. MdMYB30 was localized to the nucleus, and was highly expressed in young apple leaves. Transcription of MdMYB30 was induced by abiotic stressors, such as polyethylene glycol and abscisic acid. Scanning electron microscopy and gas chromatograph–mass spectrometry analyses demonstrated that ectopically expressing MdMYB30 in Arabidopsis changed the wax content, the number of wax crystals, and the transcription of wax-related genes. MdMYB30 bound to the MdKCS1 promoter to activate its expression and regulate wax biosynthesis. MdMYB30 also contributed to plant surface properties and increased resistance to the bacterial strain Pst DC3000. Furthermore, a virus-based transformation in apple fruits and transgenic apple calli demonstrated that MdMYB30 increased resistance to Botryosphaeria dothidea. Our findings suggest that MdMYB30 plays a vital role in the accumulation of cuticular wax and enhances disease resistance in apple.ConclusionsMdMYB30 bound to the MdKCS1 gene promoter to activate its transcription and regulate cuticular wax content and composition, which influenced the surface properties and expression of pathogenesis-related genes to resistance against pathogens. MdMYB30 appears to be a crucial element in the formation of the plant cuticle and confers apple with a tolerance to pathogens.
Highlights
The MYB transcription factor family is one of the largest transcriptional factor families in plants and plays a multifaceted role in plant growth and development
The results indicated that apple MdMYB30 exhibited the closest evolutionary relationship with pear PbMYB30 (XP_009376268), because they were in the same clade
The MdMYB30 fluorescence signal indicated that it was located in the nucleus, demonstrating that MdMYB30 as a transcription factor (TF) might target the genes localized in the nucleus that are involved in wax synthesis
Summary
The MYB transcription factor family is one of the largest transcriptional factor families in plants and plays a multifaceted role in plant growth and development. MYB transcription factors involved in pathogen resistance in apple remain poorly understood. Apple (Malus × domestica) is an important fruit crop that is commonly grown worldwide. Cuticular wax is responsible for resistance to apple pathogens and gloss. An epicuticular film of wax crystals covers the plant surface [1]. The basic constituents of plant cuticular wax are very long chain fatty acids (VLCFAs) and their derivatives. The cuticular synthetic pathway can be divided into three reactions: (1) de novo synthesis of C16 and C18 fatty acids; (2) extension of VLCFAs: Zhang et al BMC Plant Biology (2019) 19:362 the C16 and C18 fatty acids produced during the first stage extend on the endoplasmic reticulum to form C20–C36 VLCFAs; and (3) synthesis of derivatives of VLCFA, such as aldehydes, alcohols, alkanes, ketones, and esters [2]
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