Potential roles of melatonin and ABA on apple dwarfing in semi-arid area of Xinjiang China

Abstract

Dwarfing is a typic breeding trait for mechanical strengthening and relatively high yield in modern apple orchards. Clarification of the mechanisms associated with dwarfing is important for use of molecular technology to breed apple. Herein, we identified four dwarfing apple germplasms in semi-arid area of Xinjiang, China. The internodal distance of these four germplasms were significantly shorter than non-dwarfing control. Their high melatonin (MT) contents are negatively associated with their malondialdehyde (MDA) levels and oxidative damage. In addition, among the detected hormones including auxin (IAA), gibberellin (GA), brassinolide (BR), zeatin-riboside (ZR), and abscisic acid (ABA), only ABA and ZR levels were in good correlation with the dwarfing phenotype. The qPCR results showed that the expression of melatonin synthetic enzyme genes MdASMT1 and MdSNAT5, ABA synthetic enzyme gene MdAAO3 and degradative gene MdCYP707A, ZR synthetic enzyme gene MdIPT5 all correlated well with the enhanced levels of MT, ABA and the reduced level of of ZR in the dwarfing germplasms. Furthermore, the significantly higher expression of ABA marker genes (MdRD22 and MdRD29) and the lower expression of ZR marker genes (MdRR1 and MdRR2) in all the four dwarf germplasms were consistent with the ABA and ZR levels. Considering the yearly long-term drought occurring in Xinjiang, China, it seems that dwarfing with high contents of MT and ABA may be a good strategy for these germplasms to survive against drought stress. This trait of dwarfing may also benefit apple production and breeding in this semi-arid area.

Rol de los brasinoesteroides en frutales con énfasis en condiciones de estrés abiótico: Una revisión

“…En manzana "Golden Delicious" se investigaron los niveles de transcripción de MdPRE y se encontró que la expresión se indujo por ABA, BR, ácido indolacético (AIA), y giberelinas (GA) siendo las expresiones de PRE1, PRE3, PRE4 y PRE6 las inducidas por BR y ABA (Li et al, 2022b). También se evaluó el papel de BRs en el enanismo del manzano evaluando el genotipo Dwarf1-4 en donde se expresa el gen MdNAC1 y se manifiesta una síntesis reducida de ABA y BR, sin embargo, no es claro aún si esta es la causa principal del enanismo (Yan et al, 2022).…”