Overexpression of a Novel <i>LcKNOX</i> Transcription Factor from <i>Liriodendron chinense</i> Induces Lobed Leaves in <i>Arabidopsis thaliana</i>

• Main Authors: Jikai Ma, Guoguo Mei, Huanhuan Liu, Huogen Li
• Format: Article
• Language: English
• Published: MDPI AG 2019-12-01
• Series: Forests
• Subjects: leaf shape; primordia initiation; axes growth; transcription factors; phytohormone
• Online Access: https://www.mdpi.com/1999-4907/11/1/33

<i>Liriodendron chinense</i> is a common ornamental tree that has attractive leaves, which is a valuable trait for use in landscape architecture. In this work, we aimed to identify the potential genes that control and regulate the development of <i>L. chinense</i> leaf lobes. Based on the transcriptome data for the leaf developmental stages we previously generated, two candidate genes were identified in this study. <i>KNOTTED-LIKE HOMEOBOX</i>(<i>KNOX</i>), encoding homeobox family proteins, play a large role in leaf lobe and leaf complexity regulation. Here, two full length <i>KNOX</i> genes from <i>L. chinense</i> were amplified and named <i>LcKNOX1</i> and <i>LcKNOX6</i> according to their sequence similarities with the respective <i>Arabidopsis thaliana KNOX</i> family genes. Overexpression vectors were constructed and subsequently transformed into wild type (WT) <i>A. thaliana</i>. Additionally, <i>LcKNOX6</i> was expressed in tobacco leaves to examine its subcellular localization, and the <i>35S::LcKNOX6</i> transgenic <i>A. thaliana</i> leaf cells were imaged with the use of SEM. The expression of several genes that participate in <i>KNOX</i> gene regulation were validated by quantitative real-time PCR. The results show that <i>LcKNOX1</i> produces almost the same phenotype as that found in WT <i>A. thaliana.</i> Notably, the <i>LcKNOX6-1</i> lines presented deep leaf lobes that were similar to <i>L. chinense</i> leaf lobes. Two <i>35S::LcKNOX6</i> lines induced an abnormal growth phenotype whose seeds were abortive. In short, these results indicate that the <i>LcKNOX6</i> gene might affect leaf development in <i>A. thaliana</i> and provide insights into the regulation of <i>L. chinense</i> leaf shaping.