Genome-Wide Identification and Expression Analysis of LBD Transcription Factor Genes in Passion Fruit ().

The lateral organ boundary domain () gene is a plant-specific transcription factor that plays a crucial role in plant growth and development, including the development of lateral vegetative organs such as leaf and root development, as well as floral organs such as sepal, petal, and pollen development. Passion fruit is a tropical fruit with important agricultural, economic and ornamental value. However, there is no systematic research report available on the gene family of passion fruit. In this study, a genome-wide analysis of passion fruit genes identified 33 that were unevenly distributed across nine chromosomes. According to phylogenetic and gene structure analysis, were divided into two categories: Class I (27) and Class II (6). Homologous protein modeling results showed that the gene members of the two subfamilies were structurally and functionally similar. -acting element and target gene prediction analysis suggested that might participate in various biological processes by regulating diverse target genes involved in growth and development, metabolism, hormones and stress response. Collinearity analysis indicated that the expansion of the gene family likely took place mainly by segmental duplication, and some duplicated gene pairs such as might show functional redundancy, while most duplicated gene pairs such as showed different expression profiles indicating their functional diversification. After filtering low expressed genes, all Class Id s were more highly expressed during pollen development. At the same, all Class Ic and many other were relatively highly expressed during ovule development, similar with their homologous genes in Arabidopsis, indicating their potential regulatory roles in reproductive tissue development in passion fruit. that were highly expressed in floral tissues were also expressed at a higher level in tendrils with some differences, indicating the close relationships of tendrils to floral tissues. Some genes such as might be simultaneously related to floral development and leaf early formation in passion fruit, while other showed a strong tissue-specific expression. For example, were specifically expressed in floral tissues, while were only highly expressed in fruit, suggesting their specific function in the development of certain tissues. A qRT-PCR was conducted to verify the expression levels of six in different tissues. Our analysis provides a basis for the functional analysis of genes and new insights into their regulatory roles in floral and vegetative tissue development.