Publication Overview
Abstract The spur-type growth habit in apple trees is characterized by short internodes, increased
number of fruiting spurs, and compact growth that promotes flowering and facilitates
management practices, such as pruning. The molecular mechanisms responsible for
regulating spur-type growth have not been elucidated. In the present study, miRNAs
and the expression of their potential target genes were evaluated in shoot tips of
“Nagafu 2” (CF) and spur-type bud mutation “Yanfu 6” (YF). A total of 700 mature
miRNAs were identified, including 202 known apple miRNAs and 498 potential novel
miRNA candidates. A comparison of miRNA expression in CF and YF revealed 135
differentially expressed genes, most of which were downregulated in YF. YF also had
lower levels of GA, ZR, IAA, and ABA hormones, relative to CF. Exogenous applications
of GA promoted YF shoot growth. Based on the obtained results, a regulatory network
involving plant hormones, miRNA, and their potential target genes is proposed for the
molecular mechanism regulating the growth of YF. miRNA164, miRNA166, miRNA171,
and their potential targets, and associated plant hormones, appear to regulate shoot
apical meristem (SAM) growth. miRNA159, miRNA167, miRNA396, and their potential
targets, and associated plant hormones appear to regulate cell division and internode
length. This study provides a foundation for further studies designed to elucidate the
mechanism underlying spur-type apple architecture.
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