AUTHOR=Li Fang , Li Jinjin , Qian Ming , Han Mingyu , Cao Lijun , Liu Hangkong , Zhang Dong , Zhao Caiping 

TITLE=Identification of Peach NAP Transcription Factor Genes and Characterization of their Expression in Vegetative and Reproductive Organs during Development and Senescence

JOURNAL=Frontiers in Plant Science

VOLUME=7

YEAR=2016

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2016.00147

DOI=10.3389/fpls.2016.00147

ISSN=1664-462X

ABSTRACT=<p>The NAP (NAC-like, activated by AP<sub>3</sub>/P<sub>1</sub>) transcription factor belongs to a subfamily of the NAC transcription factor family, and is believed to have an important role in regulating plant growth and development. However, there is very little information about this subfamily in Rosaceous plants. We identified seven <italic>NAP</italic> genes in the peach genome. <italic>PpNAP2</italic> was categorized in the NAP I group, and contained a conserved transcription activation region. The other <italic>PpNAP</italic> genes belonged to the NAP II group. The expression patterns of the <italic>PpNAP</italic> genes differed in various organs and developmental stages. <italic>PpNAP1</italic> and <italic>PpNAP2</italic> were highly expressed in mature and senescing flowers, but not in leaves, fruits, and flower buds. <italic>PpNAP3</italic> and <italic>PpNAP5</italic> were only expressed in leaves. The <italic>PpNAP4</italic> expression level was high in mature and senescing fruits, while <italic>PpNAP6</italic> and <italic>PpNAP7</italic> expression was up-regulated in mature and senescent leaves and flowers. During the fruit development period, the <italic>PpNAP4</italic> and <italic>PpNAP6</italic> expression levels rapidly increased during the S1 and S4 stages, which suggests these genes are involved in the first exponential growth phase and fruit ripening. During the fruit ripening and softening period, the <italic>PpNAP1</italic>, <italic>PpNAP4</italic>, and <italic>PpNAP6</italic> expression levels were high during the early storage period, which was accompanied by a rapid increase in ethylene production. <italic>PpNAP1</italic>, <italic>PpNAP4</italic>, and <italic>PpNAP6</italic> expression slowly increased during the middle or late storage periods, and peaked at the end of the storage period. Additionally, abscisic acid (ABA)-treated fruits were softer and produced more ethylene than the controls. Furthermore, the <italic>PpNAP1</italic>, <italic>PpNAP4</italic>, and <italic>PpNAP6</italic> expression levels were higher in ABA-treated fruits. These results suggest that <italic>PpNAP1</italic>, <italic>PpNAP4</italic>, and <italic>PpNAP6</italic> are responsive to ABA and may regulate peach fruit ripening.</p>