RESUMO
Branch number is one of the most important agronomic traits of fruit trees such as peach. Little is known about how LncRNA and/or miRNA modules regulate branching through transcription factors. Here, we used molecular and genetic tools to clarify the molecular mechanisms underlying brassinosteroid (BR) altering plant branching. We found that the number of sylleptic branch and BR content in pillar peach ('Zhaoshouhong') was lower than those of standard type ('Okubo'), and exogenous BR application could significantly promote branching. PpTCP4 expressed great differentially comparing 'Zhaoshouhong' with 'Okubo'. PpTCP4 could directly bind to DWARF2 (PpD2) and inhibited its expression. PpD2 was the only one differentially expressed key gene in the path of BR biosynthesis. At the same time, PpTCP4 was identified as a target of miR6288b-3p. LncRNA1 could act as the endogenous target mimic of miR6288b-3p and repress expression of miR6288b-3p. Three deletions and five SNP sites of lncRNA1 promoter were found in 'Zhaoshouhong', which was an important cause of different mRNA level of PpTCP4 and BR content. Moreover, overexpressed PpTCP4 significantly inhibited branching. A novel mechanism in which the lncRNA1-miR6288b-3p-PpTCP4-PpD2 module regulates peach branching number was proposed.
Assuntos
Brassinosteroides , Regulação da Expressão Gênica de Plantas , MicroRNAs , Proteínas de Plantas , Prunus persica , RNA Longo não Codificante , RNA Longo não Codificante/genética , RNA Longo não Codificante/metabolismo , MicroRNAs/genética , MicroRNAs/metabolismo , Prunus persica/genética , Prunus persica/crescimento & desenvolvimento , Prunus persica/metabolismo , Brassinosteroides/metabolismo , Brassinosteroides/biossíntese , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Regiões Promotoras Genéticas/genética , Sequência de Bases , Polimorfismo de Nucleotídeo Único/genética , Genes de PlantasRESUMO
Salt stress is a critical limiting factor for fruit yield and quality of apples. Brassinosteroids (BRs) play an important role in response to abiotic stresses. In the present study, application of 2,4- Epicastasterone on seedlings of Malus 'M9T337' and Malus domestica 'Gala3' alleviated the physiological effects, such as growth inhibition and leaf yellowing, induced by salt stress. Further analysis revealed that treatment with NaCl induced expression of genes involved in BR biosynthesis in 'M9T337' and 'Gala3'. Among which, the expression of BR biosynthetic gene MdBR6OX2 showed a three-fold upregulation upon salt treatment, suggesting its potential role in response to salt stress in apple. MdBR6OX2, belonging to the CYP450 family, contains a signal peptide region and a P450 domain. Expression patterns analysis showed that the expression of MdBR6OX2 can be significantly induced by different abiotic stresses. Overexpressing MdBR6OX2 enhanced the tolerance of apple callis to salt stress, and the contents of endogenous BR-related compounds, such as Typhastero (TY), Castasterone (CS) and Brassinolide (BL) were significantly increased in transgenic calli compared with that of wild-type. Extopic expression of MdBR6OX2 enhanced tolerance to salt stress in Arabidopsis. Genes associated with salt stress were significantly up-regulated, and the contents of BR-related compounds were significantly elevated under salt stress. Our data revealed that BR-biosynthetic gene MdBR6OX2 positively regulates salt stress tolerance in both apple calli and Arabidopsis.