Project description:• To dissect how the genes are dynamically and differentially expressed during fruit development in sweet orange, a comprehensive transcriptomic study was performed in a pleiotropic mutant (MT) and its wild type (WT). • The detection of the fruit transcriptomic changes was conducted at five stages of fruit development by deep sequencing; the obtained millions of reliable tags were mapped on orange unigenes and subjected to cluster analysis and functional categorization. Sugar and organic acid contents were determined based on the prediction of differential biological processes. • The global clustering analysis revealed a total of 14 expression patterns for the genes involved in fruit development of sweet orange. More than 94% of the genes showed differential expression during fruit development. Comparative transcripts profiling between WT and MT revealed that between 410 and 634 genes were significantly differentially expressed at the five stages. Functional categorization indicated that TCA cycle, carotenoid biosynthesis, and pentose phosphate pathway (OPP) were among the most regulated pathways. • This study provided a dynamic-view of the transcriptome changes during fruit ripening in sweet orange; the results highlighted a set of molecular processes involved in the formation of the mutation trait in the orange fruits. Investigate the transcriptome changes during five fruit developmental stages of two sweet orange genotypes
Project description:• To dissect how the genes are dynamically and differentially expressed during fruit development in sweet orange, a comprehensive transcriptomic study was performed in a pleiotropic mutant (MT) and its wild type (WT). • The detection of the fruit transcriptomic changes was conducted at five stages of fruit development by deep sequencing; the obtained millions of reliable tags were mapped on orange unigenes and subjected to cluster analysis and functional categorization. Sugar and organic acid contents were determined based on the prediction of differential biological processes. • The global clustering analysis revealed a total of 14 expression patterns for the genes involved in fruit development of sweet orange. More than 94% of the genes showed differential expression during fruit development. Comparative transcripts profiling between WT and MT revealed that between 410 and 634 genes were significantly differentially expressed at the five stages. Functional categorization indicated that TCA cycle, carotenoid biosynthesis, and pentose phosphate pathway (OPP) were among the most regulated pathways. • This study provided a dynamic-view of the transcriptome changes during fruit ripening in sweet orange; the results highlighted a set of molecular processes involved in the formation of the mutation trait in the orange fruits.
Project description:Citrus greening or huanglongbing (HLB) is a devastating disease of citrus. HLB is associated with the phloem-limited fastidious prokaryotic alpha-proteobacterium Candidatus Liberibacter spp. In this report, we used sweet orange (Citrus sinensis) leaf tissue infected with 'Ca. Liberibacter asiaticus' and compared this with healthy controls. Investigation of the host response was examined with citrus microarray hybridization based on 30,171 sets expressed sequence tag sequences from several citrus species and hybrids. The microarray analysis indicated that HLB infection significantly affected expression of 624 genes whose encoded proteins were categorized according to function. The categories included genes associated with sugar metabolism, plant defense, phytohormone, and cell wall metabolism, as well as 14 other gene categories. Young, healthy Valencia sweet orange (C. sinensis) plants were graft inoculated with budwood from Ca. L. asiaticus-infected citrus plants. Prior to the innocualtion, the plants were confirmed to be Ca. L. asiaticus-free in ordinary and quantitative PCR tests. The presence of the bacteria in the inoculated plants was confirmed in both conventional and quantitative PCR with specific primers to Ca. L. asiaticus. The stem and root samples used for RNA extraction and hybridization on Affymetrix microarrays were obtained from three symptomatic and three healthy control trees of similar size, approximately 1 year after inoculation.
Project description:Citrus and most other fruit crops are commercially propagated via grafting, which ensures trees have consistent fruit traits combined with favorable traits from the rootstock such as soil adaptability, vigor, and resistance to soil pathogens. Breeding new rootstocks requires careful agronomic evaluations, and widespread use of new rootstocks and scions requires graft compatibility with commercially important scions and rootstocks. Graft incompatibility can occur when the scion and rootstock are not able to form a permanent, healthy union. Understanding and preventing graft incompatibility is therefore of paramount importance in the breeding of new fruit cultivars and in the choice of scion and rootstock by growers. The rootstock US-1283 is a citrandarin generated from a cross of ‘Ninkat’ mandarin (Citrus reticulata) and ‘Gotha Road’ #6 trifoliate orange (Poncirus trifoliata). It was released in 2014 after years of field evaluation because of its superior productivity and good fruit quality on ‘Hamlin’ sweet orange (C. sinensis) under Florida’s growing conditions. Subsequently, it was observed that trees of ‘Bearss’ lemon (C. limon) and ‘Valencia’ sweet orange (C. sinensis) grafted onto US-1283 exhibited apparent incompatible and unhealthy growth near the graft union. The incompatibility manifested as stem grooving and necrosis underneath the bark on the rootstock side of the graft. A genetically similar citrandarin rootstock, US-812 (C. reticulata ‘Sunki’ × P. trifoliata ‘Benecke’), is fully graft compatible with the same scions. Transcriptome analysis was performed on the vascular tissues above and below the graft union of compatible US-812 and incompatible US-1283 graft combinations with ‘Bearss’ and ‘Valencia’ to identify expression networks associated with incompatibility and help understand the processes and potential causes of incompatibility in citrus. Transcriptional reprogramming was stronger in the incompatible rootstock than in the grafted scions. Functional analysis of the transcriptional events below the graft unions of US-1283 incompatible combinations revealed differentially expression genes (DEGs) associated with oxidative stress and plant defense, among other pathways, similar to a pathogen-induced immune response localized to the rootstock, although no known pathogens were detected in the assayed plants. These changes were not observed above the graft unions.Differentially expressed genes (DEGs) in US-1283, but not the scions, were associated with oxidative stress and plant defense, among others, similar to a pathogen-induced immune response localized to the rootstock. No pathogen infection was detected. It is hypothesized this response could have been triggered by signaling miscommunications between rootstock and scion either through 1) unknown molecules from the scion that were perceived as danger signals by the rootstock, 2) missing signals from the scion or missing receptors in the rootstock necessary for the formation of a healthy graft union, 3) the overall perception of the scion by the rootstock as non-self, or 4) a combination of the above.
Project description:To identify genes associated with citrus peel development and manifestation of peel disorders, we analyzed flavedo, albedo and juice sac tissues from five types of citrus fruit including, mandarin orange, navel orange, valencia orange, grapefruit and lemon.
Project description:This SuperSeries is composed of the following subset Series: GSE41309: Differential expression in response to water deficit in diploid leaves of sweet orange scion grafted alternatively on a diploid or auto-tetraploid Rangpur lime rootstock: data concerning the scion grafted onto diploid rootstock. GSE41310: Differential expression in response to water deficit in diploid leaves of sweet orange scion grafted alternatively on a diploid or auto-tetraploid Rangpur lime rootstock: data concerning the scion grafted onto tetraploid rootstock Refer to individual Series
Project description:We have used the citrus GeneChip array (GPL5731) to survey the transcription profiles of sweet orange in response to the bacterial pathogens Xanthomonas axonopodis pv. citri (Xac) and Xanthomonas axonopodis pv. aurantifolii (Xaa). Xac is the causal agent of the citrus canker disease on a wide range of citrus species, including sweet oranges (Citrus sinensis). On the other hand, Xaa is pathogenic to Mexican lime (Citrus aurantifolia) only, and in sweet orange it triggers a defense response. In order to identify the genes induced during the defense response (Xaa-responsive genes) or citrus canker development (Xac-responsive genes), we conducted microarrays hybridization experiments at 6 and 48 hours after bacterial infiltration (habi). The analysis revealed that genes commonly modulated by Xac and Xaa are associated with basal defenses normally triggered by pathogen-associated molecular patterns, including those involved in reactive oxygen species production and lignification. Significantly, Xac-infected leaves showed considerable changes in the transcriptional profiles of defense-, cell wall-, vesicle trafficking- and cell growth-related genes between 6 and 48 habi. This is consistent with the notion that Xac suppresses host defenses near the beginning of the infection and simultaneously changes the physiological status of the host to promote cell enlargement and division. Finally, Xaa triggered a MAP kinase signaling pathway involving WRKY and ethylene-responsive transcriptional factors known to activate downstream defense genes. Keywords: Comprehensive transcriptional analysis of the Citrus-Xanthomonas interaction Adult leaves of sweet orange were infiltrated with the bacterial suspensions or water (mock control). Two stages were selected after bacterial infiltration for RNA extraction and hybridization on Affymetrix microarrays. In total, these experiments consist of two biological replicates of six samples: water-infiltrated leaves, Xaa-infiltrated leaves and Xac-infiltrated leaves, at both 6 and 48 (habi).