FUNCTIONAL GAIN OF FRUIT NETTED-CRACKING IN AN INTROGRESSION LINE OF TOMATO WITH HIGHER EXPRESSION OF THE FNC GENE

• Published in: Frontiers of Agricultural Science and Engineering
• Main Author: Chunli ZHANG, Taotao WANG, Jing LI, Danqiu ZHANG, Qingmin XIE, Shoaib MUNIR, Jie YE, Hanxia LI, Yongen LU, Changxian YANG, Bo OUYANG, Yuyang ZHANG, Junhong ZHANG, Zhibiao YE
• Format: Article
• Language: English
• Published: Higher Education Press 2021-06-01
• Subjects: fine mapping|fruit netted-cracking|introgression line|transcript level
• Online Access: https://academic.hep.com.cn/fase/fileup/2095-7505/PDF/28815/1609403060111-1300824053.pdf

&lt;List&gt; &lt;ListItem&gt;&lt;ItemContent&gt;&lt;p&gt;&#8226; A novel netted-cracking fruit phenotype was discovered in tomato introgression line IL4-4.&lt;/p&gt;&lt;/ItemContent&gt;&lt;/ListItem&gt; &lt;ListItem&gt;&lt;ItemContent&gt;&lt;p&gt;&#8226; A single dominant gene (FNC) determined the fruit netted-cracking phenotype.&lt;/p&gt;&lt;/ItemContent&gt;&lt;/ListItem&gt; &lt;ListItem&gt;&lt;ItemContent&gt;&lt;p&gt;&#8226; The high transcript level of FNC results in the functional gain of fruit netted-cracking and it was found to be a common mechanism in a diverse range of plant species.&lt;/p&gt;&lt;/ItemContent&gt;&lt;/ListItem&gt;&lt;/List&gt;&lt;/p&gt; &lt;p&gt;Fruit cracking is a major disorder that affects the integrity of fruit and reduces the commercial value of tomato and other fleshy fruit. Here, we have found a novel fruit &#8216;netted-cracking&#8217; (FNC) phenotype in tomato introgression line IL4-4 which is present in neither the donor parent (LA0716) nor the receptor parent (M82). An F<inf>2</inf> population was generated by crossing IL4-4 with M82 to genetically characterize the FNC gene and this showed that a single dominant gene determined fruit netted-cracking. Further map-based cloning narrowed down the FNC locus to a 230 kb region on chromosome 4. Sequencing and annotation analysis show that FNC (Solyc04 g082540) was the most likely candidate gene. Functional characterization of FNC by overexpressing FNC^AC and FNC^IL4-4 resulted in the fruit netted-cracking phenotype, suggesting that the FNC transcript level results in the functional gain of fruit netted-cracking. These findings were further confirmed by FNC ortholog in netted-cracking pepper and melon, indicating a common regulatory mechanism in different plant species. Furthermore, cytoplasm and nucleus-localized FNC indicates increased expression of genes involved in suberin, lignin, lipid transport and cell wall metabolism. These findings provide novel genetic insights into fruit netted-cracking and offer a way to promote molecular improvement toward cracking resistant cultivars.