RESUMEN
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.
Asunto(s)
Arabidopsis , Brasinoesteroides , Regulación de la Expresión Génica de las Plantas , Malus , Proteínas de Plantas , Tolerancia a la Sal , Malus/genética , Malus/metabolismo , Malus/efectos de los fármacos , Brasinoesteroides/metabolismo , Brasinoesteroides/biosíntesis , Brasinoesteroides/farmacología , Arabidopsis/genética , Arabidopsis/metabolismo , Arabidopsis/efectos de los fármacos , Tolerancia a la Sal/genética , Regulación de la Expresión Génica de las Plantas/efectos de los fármacos , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Plantas Modificadas Genéticamente , Estrés Salino/genética , Sistema Enzimático del Citocromo P-450/genética , Sistema Enzimático del Citocromo P-450/metabolismoRESUMEN
Drought stress is one of the main environmental factors limiting plant growth and development. Plants adapt to changing soil moisture by modifying root architecture, inducing stomatal closure, and inhibiting shoot growth. The AP2/ERF transcription factor DREB2A plays a key role in maintaining plant growth in response to drought stress, but the molecular mechanism underlying this process remains to be elucidated. Here, it was found that overexpression of MdDREB2A positively regulated nitrogen utilisation by interacting with DRE cis-elements of the MdNIR1 promoter. Meanwhile, MdDREB2A could also directly bind to the promoter of MdSWEET12, which may enhance root development and nitrogen assimilation, ultimately promoting plant growth. Overall, this regulatory mechanism provides an idea for plants in coordinating with drought tolerance and nitrogen assimilation to maintain optimal plant growth and development under drought stress.