Abstract
Plant height is an important trait for fruit trees. The dwarf characteristic is commonly associated with highly efficient fruit production, a major objective when breeding for apple (Malus domestica). We studied the function of MdNAC1, a novel NAC transcription factor (TF) gene in apple related to plant dwarfing. Localized primarily to the nucleus, MdNAC1 has transcriptional activity in yeast cells. Overexpression of the gene results in a dwarf phenotype in transgenic apple plants. Their reduction in size is manifested by shorter, thinner stems and roots, and a smaller leaf area. The transgenics also have shorter internodes and fewer cells in the stems. Levels of endogenous abscisic acid (ABA) and brassinosteroid (BR) are lower in the transgenic plants, and expression is decreased for genes involved in the biosynthesis of those phytohormones. All of these findings demonstrate that MdNAC1 has a role in plants dwarfism, probably by regulating ABA and BR production.
Highlights
Apple (Malus domestica) is one of the most widely cultivated fruit trees worldwide
The expression of the MdNAC1 gene was tested in dwarfing and nondwarfing apple rootstocks. Expression of it was significantly higher in the three dwarfing rootstocks (M9, SH2, and T337) than that in the three nondwarfing rootstock (Malus zumi, Malus pruifolia, and Malus robusta) (Figure S1). These results suggested that it possible plays a role in apple dwarfing
These results demonstrated that overexpression of MdNAC1 in apple modifies the abscisic acid (ABA) and Several NAC transcription factor (TF) are involved in plant dwarfism and/or growth inhibition in plants
Summary
The incubator conditions included 24◦ C/20◦ C (day/night), 16 h photoperiod, and a light intensity of 100 μmol m−2 s−1 After another month, plants of uniform size from each genotype were moved to plastic pots containing a mixture of forest soil and organic substrate (5:1, v:v), and were exposed to natural, outdoor conditions for another month. Plants of uniform size from each genotype were moved to plastic pots containing a mixture of forest soil and organic substrate (5:1, v:v), and were exposed to natural, outdoor conditions for another month They were transferred to the greenhouse where the experiments were conducted. A total of 40 plants for each line were used in the experiments
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