AUTHOR=Muhammad Noor , Luo Zhi , Zhao Xin , Yang Meng , Liu Zhiguo , Liu Mengjun 

TITLE=Transcriptome-wide expression analysis of MYB gene family leads to functional characterization of flavonoid biosynthesis in fruit coloration of Ziziphus Mill

JOURNAL=Frontiers in Plant Science

VOLUME=14

YEAR=2023

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2023.1171288

DOI=10.3389/fpls.2023.1171288

ISSN=1664-462X

ABSTRACT=<p>The <italic>Ziziphus mauritiana</italic> Lam. and <italic>Z. jujuba</italic> Mill. are the two most economically important members of the genus <italic>Ziziphus.</italic> The fruit color of <italic>Z. mauritiana</italic> remains green throughout fruit development in the majority of commercial cultivars, whereas its close relative, <italic>Z. jujuba</italic> Mill. turns from green to red in all cultivars. However, the lack of transcriptomic and genomic information confines our understanding of the molecular mechanisms underlying fruit coloration in <italic>Z. mauritiana</italic> (Ber). In the present study, we performed the transcriptome-wide analysis of MYB transcription factors (TFs) genes in <italic>Z. mauritiana</italic> and <italic>Z. jujuba</italic>, and identified 56 ZmMYB and 60 ZjMYB TFs in <italic>Z. mauritiana</italic> and <italic>Z. jujuba</italic>, respectively. Through transcriptomic expression analysis, four similar <italic>MYB</italic> genes (<italic>ZmMYB/ZjMYB13, ZmMYB/ZjMYB44, ZmMYB/ZjMYB50</italic>, and <italic>ZmMYB/ZjMYB56)</italic> from <italic>Z. mauritiana</italic> and <italic>Z. jujuba</italic> were selected as candidate key genes regulating flavonoid biosynthesis. Among these genes, the <italic>ZjMYB44</italic> gene was transiently highly expressed in fruit, and flavonoid content accumulation also increased, indicating that this gene can influence flavonoid content during the period of fruit coloration in <italic>Z. jujuba</italic>. The current study adds to our understanding of the classification of genes, motif structure, and predicted functions of the MYB TFs, as well as identifying MYBs that regulate flavonoid biosynthesis in <italic>Ziziphus</italic> (<italic>Z. mauritiana</italic> and <italic>Z. jujuba</italic>). Based on this information, we concluded that <italic>MYB44</italic> is involved in the flavonoids biosynthesis pathway during the fruit coloring of <italic>Ziziphus</italic>. Our research results provide an important understanding of the molecular mechanism of flavonoid biosynthesis resulting in fruit coloration and laying a foundation for further genetic improvement of fruit color in <italic>Ziziphus</italic>.</p>