Expression Analysis of TCP Genes in Peach Reveals an Involvement of PpTCP.A2 in Ethylene Biosynthesis During Fruit Ripening

Abstract

Plant-specific TCP transcription factor has been studied in plant growth and development, but little is known the roles during fruit development and ripening. Based on phylogenetic analysis, in this study, the 20 TCP genes isolated from peach were divided into two classes (I and II) comprised by four groups (A → D), and distributed into 19 clusters. Expression profiles of TCP genes in peach were analyzed to evaluate their potential roles during fruit development and ripening. The result showed that there are four genes (PpTCP.A2, PpTCP.A10, PpTCP.B1, and PpTCP.C1) and each gene had similar expression patterns detected by qRT-PCR to that tested by RNA-Seq, and higher expressed in fruitlets than in other developmental and ripening fruits, suggesting that these four genes were probably related to early development in peach fruit. Noteworthy, PpTCP.A2 was lower expressed in ripening fruits than in developmental or pre-ripening fruits of 11 peach cultivars, and virus-induced silencing PpTCP.A2 increased ethylene production and promoted PpACS1, but not PpACO1 and PpendoPGM expression. This result indicates that PpTCP.A2 was a transcription repressor, which could regulate ethylene biosynthesis by affecting PpACS1 expression, and thus should be involved in fruit ripening.