Project description:Transcription profiling of citrus rootstock Poncirus trifoliata (L.) Raf. Keywords: Abiotic stress (Iron chlorosis) Total RNA from four replicates for each sample category (Poncirus trifoliata (L.) Raf watered for 60 days with 18 uM Fe-EDDHA or without Fe-EDDHA) were generated and compared.
Project description:To date, little is known about molecular mechanisms by which woody plants engage symbiosis with arbuscular mycorrhizal (AM) fungi. Here we investigated transcriptome changes in the roots of Poncirus trifoliata (the most common citrus rootstock) that are induced during colonization of an AM fungus Glomus versiforme (Gv). A total of 282 Poncirus genes were differentially expressed in response to Gv colonization, of which 138 could identify homologous genes from the model legume Medicago truncatula that also exhibit similar AM-induced transcriptional changes, while the remaining 144 do not. A high proportion of the AM-responsive Poncirus genes are predicted to be involved in transcription regulation, transport process, cellular organization and protein degradation, implicating these processes in the establishment of AM symbiosis. Promoter-GUS analysis of six AM-induced Poncirus genes [encoding an exocyst subunit (PtrEXO70I), two transcription factors (PtNAC1 and PtPALM1), one chitinase (PtrChit2), one plastid movement associated protein (PtrPMI2) and one lipase (PtrLipase3)] showed that all of them exhibit specific expression in arbuscule-containing root cortical cells, suggesting their potential involvement in establishing AM symbiosis. Notably, down-regulation of the ortholog of PtrExo70I in Medicago by RNAi significantly impaired arbuscule development, indicating that Exo70I is an important host component required for arbuscule development in root cortical cells. This study not only helps identify conserved host genes engaged in AM symbiosis but should also guide future mechanistic studies of potentially Poncirus-specific events during its symbiosis with AM fungi.
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:Solexa sequencing was performed at different developmental stages both an early flowering mutant of trifoliate orange (precocious trifoliate orange, Poncirus trifoliata L. Raf.) and its wild-type in this study, resulting in the obtainment of a total of 143 known miRNAs belonging to 99 families and 75 novel miRNAs in four libraries. A total of 317 potential target genes were predicted based on the 50 novel miRNAs families, GO and KEGG annotation revealed that high ranked miRNA-target genes are those implicated in diverse cellular processes in plants, including development, transcription, protein degradation and cross adaptation. To characterize those miRNAs expressed at the juvenile and adult development stages of the mutant and its wild-type, further analysis on the expression profiles of several miRNAs through real-time PCR was performed. The results revealed that most miRNAs were down-regulated at adult stage compared with juvenile stage both the mutant and its wild-type. These results indicate that both conserved and novel miRNAs may play important roles in citrus growth and development, stress responses and other physiological processes.
