Project description:Roughing disorder (RD) is a significant quality barrier in citrus fruit, occurring more easily on easy-peeling mandarins. As RD is not yet well understood, this study aimed to examine the changes and synergic molecular processes involved. Peel with RD was induced by severely defruiting Satsuma mandarin trees. Morphology observations, RNA-sequencing and untargeted and targeted metabolic analyses were conducted.
Project description:Somatic embryogenesis in nucellar tissues is widely recognized to induce polyembryony in major citrus varieties such as sweet oranges, satsuma mandarins and lemons. This capability for apomixis is attractive in agricultural production systems using hybrid seeds, and many studies have been performed to elucidate the molecular mechanisms of various types of apomixis. To identify the gene responsible for somatic embryogenesis in citrus, a custom oligo-DNA microarray including predicted genes in the citrus polyembryonic locus was used to compare the expression profiles in reproductive tissues between monoembryonic and polyembryonic varieties. The full length of CitRKD1, which was identified as a candidate gene responsible for citrus somatic embryogenesis, was isolated from satsuma mandarin and its molecular function was investigated using transgenic ‘Hamlin’ sweet orange by antisense-overexpression. The candidate gene CitRKD1, predominantly transcribed in reproductive tissues of polyembryonic varieties, is a member of the plant RWP-RK domain proteins. CitRKD1 of satsuma mandarin comprised two alleles (CitRKD1-mg1 and CitRKD1-mg2) at the polyembryonic locus controlling embryony type (mono/polyembryony) that were structurally divided into two types with or without a miniature inverted-repeat transposable element (MITE)-like insertion in the upstream region. CitRKD1-mg2 with the MITE insertion was the predominant transcript in flowers and young fruits where somatic embryogenesis of nucellar cells occurred. Loss of CitRKD1 function by antisense-overexpression abolished somatic embryogenesis in transgenic sweet orange and the transgenic T1 plants were confirmed to derive from zygotic embryos produced by self-pollination by DNA diagnosis. Genotyping PCR analysis of 95 citrus traditional and breeding varieties revealed that the CitRKD1 allele with the MITE insertion (polyembryonic allele) was dominant and major citrus varieties with the polyembryonic allele produced polyembryonic seeds.
Project description:The postharvest senescence processes of citrus fruits were analyzed transcriptomic. The present study was aimed to: further uncover the rind-flesh communication of hesperidium; characterize the differential storage behaviors of different citrus varieties; reveal the important changes during storing process; and demonstrate the specific non-climacteric characteristics of citrus fruits. We chose four major table fruit varieties of citrus: satsuma mandarin (Citrus unshiu Marc) (M), ponkan (Citrus reticulata Blanco) (K), newhall navel orange (Citrus sinensis L. Osbeck) (O) and shatian pummelo (Citrus grandis Osbeck) (P). They were sampled every 10 days during 50 DAH (days after harvest), almost covering the commercial storage period of loose-skin citrus.
Project description:To characterize the site-specific methylation landscape of the Mandarin fish ranavirus (MRV) genome, whole-genome bisulfite sequencing (WGBS) was conducted on an isolated MRV strain.