AUTHOR=Yi Shan-na , Mao Jian-xin , Zhang Xin-yu , Li Xiao-ming , Zhang Zhi-hong , Li He 

TITLE=FveARF2 negatively regulates fruit ripening and quality in strawberry

JOURNAL=Frontiers in Plant Science

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2022.1023739

DOI=10.3389/fpls.2022.1023739

ISSN=1664-462X

ABSTRACT=<p>Auxin response factors (ARFs) are transcription factors that play important roles in plants. ARF2 is a member of the ARF family and participates in many plant growth and developmental processes. However, the role of <italic>ARF2</italic> in strawberry fruit quality remains unclear. In this study, <italic>FveARF2</italic> was isolated from the woodland strawberry ‘Ruegen’ using reverse transcription-polymerase chain reaction (RT-PCR), which showed that <italic>FveARF2</italic> expression levels were higher in the stem than in other organs of the ‘Ruegen’ strawberry. Moreover, <italic>FaARF2</italic> was higher in the white fruit stage of cultivated strawberry fruit than in other stage. Subcellular localization analysis showed that FveARF2 is located in the nucleus, while transcriptional activation assays showed that FveARF2 inhibited transcription in yeast. Silencing <italic>FveARF2</italic> in cultivated strawberry fruit revealed earlier coloration and higher soluble solid, sugar, and anthocyanin content in the transgenic fruit than in the control fruit, overexpression of <italic>FveARF2</italic> in strawberry fruit delayed ripening and lower soluble solid, sugar, and anthocyanin content compared to the control fruit. Gene expression analysis indicated that the transcription levels of the fruit ripening genes <italic>FaSUT1</italic>, <italic>FaOMT</italic>, and <italic>FaCHS</italic> increased in <italic>FveARF2-RNAi</italic> fruit and decreased in <italic>FveARF2-OE</italic> fruit, when compared with the control. Furthermore, yeast one-hybrid (Y1H) and GUS activity experiments showed that FveARF2 can directly bind to the AuxRE (TGTCTC) element in the <italic>FaSUT1</italic>, <italic>FaOMT</italic>, and <italic>FaCHS</italic> promoters <italic>in vitro</italic> and <italic>in vivo</italic>. Potassium ion supplementation improved the quality of strawberry fruit, while silencing <italic>FveARF2</italic> increased potassium ion content in transgenic fruit. The Y1H and GUS activity experiments also confirmed that FveARF2 could directly bind to the promoter of <italic>FveKT12</italic>, a potassium transporter gene, and inhibited its expression. Taken together, we found that <italic>FveARF2</italic> can negatively regulate strawberry fruit ripening and quality, which provides new insight for further study of the molecular mechanism of strawberry fruit ripening.</p>