Abstract
Adventitious root (AR) formation is indispensable for vegetative asexual propagation. Indole-3-butyric acid (IBA) functioned indirectly as precursor of IAA in regulating AR formation. Ethylene affects auxin synthesis, transport, and/or signaling processes. However, the interactions between auxin and ethylene that control AR formation in apple have not been elucidated. In this study, we investigated the effects of IBA and its interaction with ethylene on AR development in apple. The results revealed that IBA stimulated the formation of root primordia, increased the number of ARs, and upregulated expression of genes (MdWOX11, MdLBD16, and MdLBD29) involved in AR formation. Comparison of different periods of IBA application indicated that IBA was necessary for root primordium formation, while long time IBA treatment obviously inhibited root elongation. RNA-seq analysis revealed that many plant hormone metabolism and signal transduction related genes were differentially expressed. IBA stimulated the production of ethylene during AR formation. Auxin inhibiting ARs elongation depended on ethylene. Together, our results suggest that the inhibitory role of auxin on AR elongation in apples is partially mediated by stimulated ethylene production.
Highlights
Apple (Malus domestica Borkh.) is one of the most economically important fruits worldwide and China has the largest area of apple tree cultivation (Wang et al, 2018)
Experiment 1 To investigate the roles of Indole-3-butyric acid (IBA) in primordium induction of Adventitious root (AR), stem cuttings of M9-T337 were divided into two groups: Control, for which the stem cuttings were transferred to 1/2 MS medium without IBA; and IBA treatment (IBA), for which the stem cuttings were transferred to 1/2 MS medium with 0.6 mg·L−1 IBA
There were no signs of AR formation in control cuttings before day 7
Summary
Apple (Malus domestica Borkh.) is one of the most economically important fruits worldwide and China has the largest area of apple tree cultivation (Wang et al, 2018). Apple trees are a combination of two genetically different parts: rootstock and scion. Rootstocks play a vital role in regulating the environmental adaptability and controlling the growth and development of apple trees (Atkinson et al, 2003; Gan et al, 2018). M9-T337, an excellent rootstock widely used in commercial orchards, could lead to dwarf tree architecture, early fruiting, and high fruit yield and quality (Zhang et al, 2016). Since the apple genome is highly heterozygous, vegetative propagation is widely used for experimental and commercial propagation in apple rootstock (Teixeira et al, 2019). Identification and characterization of the factors regulating AR formation and development are essential for understanding and potentially manipulating AR formation
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
