Project description:In this study, 17 plants of tetraploid “Zhique” were firstly identified by screening 570 natural seedlings of Citrus wilsonii Tanaka. These tetraploid plants showed different morphology and exhibited significantly increased drought tolerance than the diploids via determination of leaf water potential, relative water content and electrolyte leakage. Large number of genes involved in photosynthesis-responsive were differentially expressed in tetraploids under drought stress by global transcriptome analysis, which was consistent with the detection of photosynthesis indicator including photosynthetic rate, stomatal conductance, chlorophyll and so on. Compared with diploids, phosphorylation modification also plays an important role in the tetraploids after drought stress through the transcriptional and protein level analysis. Additionally, the genes involved in the phenylpropanoid biosynthesis and starch and sucrose metabolism pathways were enriched in both tetraploids and diploids in response to water deficient. Importantly, tetraploids significantly take priority over the diploid via regulating plant hormone signal transduction, especially improving the levels of 3-indoleacetic acid, abscisic acid and salicylic acid and reducing gibberellic A3 and jasmonic acid contents. Collectively, our data reveals that synergistic regulation photosynthesis, phosphorylation modification and plant hormones accumulation contribute to drought tolerance of autotetraploid in Citrus wilsonii.
Project description:Drought, heat and high light irradiation are abiotic stresses that negatively affect plant development and reduce crop productivity. The confluence of these three factors is common in nature, causing extreme situations for plants that compromise their viability. Drought and heat stress increase the saturation of the photosystem’s reaction centers, increasing sensitivity to high light irradiation. In addition, these stress conditions affect PSII integrity, alter redox balance of the electron transport chain and decrease photosynthetic rate. Here, we studied the effect of drought, high light and heat stress factorial stress combination on the photosynthetic apparatus of two citrus rootstocks, Carrizo citrange (Citrus sinensis × Poncirus trifoliata) and Cleopatra mandarin (Citrus reshni). Proteomic data, together with transcriptomic, showed the main responses of citrus plant to multiple abitoic stress conditions. The enhancement of KEGG pathways such as RNA metabolic processes and the accumulation of family proteins like HSPs were key responses to face the combination of these abiotic stress factors.
Project description:Salt stress, especially saline-alkali stress, has seriously negative effect on citrus production. Ziyang xiangcheng (Citrus junos Sieb.) (Cj) has been reported as a saline-alkali stress and iron deficiency tolerant citrus rootstock. However, the molecular mechanism of its saline-alkali stress tolerance is still not clear. Two citrus rootstocks and one navel orange scion, Cj, Poncirus trifoliate (Poncirus trifoliata (L.) Raf.) (Pt) and ‘Lane Late’ navel orange (Citrus sinensis (L.) Osb.) (LL), were used in this study. The grafted materials Cj+LL and Pt+LL grown in calcareous soil were used to identify genes and pathways responsive to saline-alkali stress using RNA-seq. The seedlings of Cj and Pt grown in the solutions with different gradient pH value were used to perform a supplement experiment. Comprehensively analyzing the data of RNA-seq, physiology and biochemistry, agronomic traits and mineral elements of Cj+LL, Pt+LL, Cj and Pt, several candidate pathways and genes were identified to be highly regulated under saline-alkali stress. Here, we propose citrate is important for the tolerance to iron deficiency and the jasmonate (JA) biosynthesis and signal transduction pathway may play a crucial role in tolerance to saline-alkali stress in citrus by interacting with other plant hormones, calcium signaling, ROS scavenging system and lignin biosynthesis.
Project description:Fruit ripening in Citrus is not well understood at the molecular level. Knowledge of the regulatory mechanism of citrus fruit ripening at the post-transcriptional level in particular is lacking. Here, we comparatively analyzed the miRNAs and their targeted genes in a spontaneous late-ripening mutant, ?Fengwan? sweet orange (MT) (Citrus sinensis L. Osbeck), and its wild-type counterpart ('Fengjie 72-1', WT). Using high-throughput sequencing of small RNAs and RNA degradome tags, we identified 107 known and 21 novel miRNAs, as well as 225 target genes. A total of 24 miRNAs (16 known miRNAs and 8 novel miRNAs) were shown to be differentially expressed between MT and WT. The expression pattern of several key miRNAs and their target genes during citrus fruit development and ripening stages was examined. Csi-miR156k, csi-miR159 and csi-miR166d suppressed specific transcription factors (GAMYBs, SPLs and ATHBs) that are supposed to be important regulators involved in citrus fruit development and ripening. In the present study, miRNA-mediated silencing of target genes was found under complicated and sensitive regulation in citrus fruit. The identification of miRNAs and their target genes provide new clues for future investigation of mechanisms that regulate citrus fruit ripening.
Project description:To investigate the cooperation of light drought with flower branches building and flower bud formation in Citrus, we set two groups including 75 days light drought (LD) and CK to uncover which target genes relatived to flower bud and branches building have been influenced by LD. We then performed gene expression profiling analysis using data obtained from RNA-seq of two different treatment.
Project description:Alkaline stress has serious negative effects on citrus production. Ziyang xiangcheng (Citrus junos Sieb. ex Tanaka) (Cj) has been reported to be a rootstock that is tolerant to alkaline stress and iron deficiency. Poncirus trifoliata (Poncirus trifoliata (L.) Raf.) (Pt), the most widely used rootstock in China, is sensitive to alkaline stress. To investigate the molecular mechanism underlying the tolerance of Cj to alkaline stress, next-generation sequencing was employed to profile the root transcriptomes and small RNAs of Cj and Pt seedlings which were cultured in nutrient solution with three gradient pH. This two-regulation level data set provides a system-level view of molecular events with precise resolution. The data suggest that the auxin pathway may play a central role in inhibitory effect of alkaline stress on root growth, and the regulation of auxin homeostasis under alkaline stress was important for citrus adapting to alkaline stress. Moreover, the JA pathway shown an opposite response to alkaline stress in Cj and Pt may contributes to the differentials of root system architecture and iron deficiency tolerance between Cj and Pt. The data set provides a wealth of genomic resources and new clues for further studying the mechanisms underlying Cj that resist alkaline stress.
Project description:Huanglongbing, or citrus greening disease, has devastated the citrus industry. It is associated with the gram negative bacterium Candidatus Liberibacter asiaticus (CLas) that can be transmitted by Diaphorina citri, the Asian citrus psyllid. For transmission to occur, CLas must cross the gut of the ACP to circulate through the insect body. The insect gut is the first site of widespread interactions between the CLas and the ACP and forms a barrier to transmission. To investigate the effect of CLas exposure on this dynamic interface, we performed RNAseq and mass spectrometry-based proteomics to analyze the transcriptome and proteome respectively of dissected ACP guts. We found changes in iron metabolism, insecticide resistance, immune system, and apoptosis. We identified 83 long non-coding RNAs that are responsive to CLas, two of which have no homology to other organisms in NCBI. We also determined that Wolbachia, a symbiont of the ACP, undergoes protein regulation when CLas is present. Fluorescent in situ hybridization (FISH) confirmed that Wolbachia and CLas can inhabit the same ACP gut cell, but do not co-localize. These data provide a snapshot of the ACP gut under normal and CLas-exposed conditions, and provide tools to better understand the insect vector of the citrus greening pathosystem.
Project description:To dissect the molecular mechanisms underlying drought tolerance (DT) in rice, transcriptome differences of a DT introgression line H471, the DT donor P28 and the drought sensitive recurrent parent HHZ under drought stress were investigated using deep transcriptome sequencing. Results revealed a differential constitutive gene expression prior to stress and distinct global transcriptome reprogramming among three genotypes under time-series drought stress, consistent with their differential genotypes and DT phenotypes.
Project description:Background: MicroRNAs play important roles in the adaptive responses of plants to nutrient deficiencies. Here, we sequenced two small RNA libraries from B-deficient and -sufficient (control) Citrus sinensis leaves, respectively, using Illumina sequencing in order to identify the potential miRNAs related to the tolerance of citrus to B-deficiency. Results: Ninety one (83 known and 8 novel) up- and 81 (75 known and 6 novel) downregulated miRNAs were isolated from B-deficient leaves. The great alteration of miRNA expression might contribute to the tolerance of citrus to B-deficiency. The adaptive responses of miRNAs to B-deficiency might related to several aspects: (a) attenuation of plant growth and development by repressing auxin signaling due to decreased TIR1 level and ARF-mediated gene expression by altering the expression of miR393, miR160 and miR3946; (b) maintaining leaf phenotype and enhancing the stress tolerance by up-regulating NACs targeted by miR159, miR782, miR3946 and miR7539; (c) activation of the stress responses and antioxidant system through down-regulating the expression of miR164, miR6260, miR5929, miR6214, miR3946 and miR3446; (d) decreasing the expression of major facilitator superfamily protein genes targeted by miR5037, thus lowering B export from plants. Also, B-deficiency-induced downregulation of miR408 might play a role in plant tolerance to B-deficiency by regulating Cu homeostasis and enhancing superoxide dismutase activity. Conclusions: Our study reveals some novel responses of citrus to B-deficiency, which increase our understanding of the adaptive mechanisms of citrus to B-deficiency at the miRNA (post-transcriptional) level.