AUTHOR=Chang Yingying , Song Xiaobo , Li Mingjun , Zhang Qixiang , Zhang Pu , Lei Xiashuo , Pei Dong 

TITLE=Characterization of walnut JrWOX11 and its overexpression provide insights into adventitious root formation and development and abiotic stress tolerance

JOURNAL=Frontiers in Plant Science

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2022.951737

DOI=10.3389/fpls.2022.951737

ISSN=1664-462X

ABSTRACT=<p>The well-developed root system enables plant survival under various environmental stresses. <italic>WUSCHEL-RELATED HOMEOBOX GENE 11</italic> (<italic>WOX11</italic>) plays a critical role in adventitious root formation and development in rice, <italic>Arabidopsis</italic>, and easy-to-root tree poplar. However, in difficult-to-root trees, the knowledge of <italic>WOX11</italic> during adventitious root formation and development remains scarce. In this study, the <italic>JrWOX11</italic> gene was isolated from a difficult-to-root tree walnut and heterologously expressed in the “84K” poplar. The results showed that <italic>JrWOX11</italic> contained a similar structure and sequence to the homologous genes in rice, <italic>Arabidopsis</italic>, and poplar, but had different numbers and types of motifs and <italic>cis</italic>-elements. JrWOX11 lacked the motif GGAIQY compared to that in easy-to-root trees. In addition, <italic>JrWOX11</italic> expression was induced by ABA, PEG, and NaCl treatments. Overexpression of <italic>JrWOX11</italic> in poplar promoted root initiation and significantly increased adventitious root (ARs) number, lateral roots (LRs) number, and root hair (RH) length. Furthermore, the aboveground biomass was notably increased under NaCl and PEG treatments in transgenic plants. When NaCl and PEG were removed, the survival rate, aerial shoot development, and <italic>de novo</italic> root organogenesis were also markedly enhanced in transgenic shoot cuttings. The study provides valuable information on the differences between <italic>JrWOX11</italic> and the homologous genes in rice, <italic>Arabidopsis</italic>, and poplar, and supports the critical role of <italic>JrWOX11</italic> in the formation of AR and tolerance to salt and osmotic stresses.</p>