Project description:High-throughput small RNA and degradome sequencing were performed to identify a large number of miRNAs and their targets. Differential expression of several miRNAs reveals that miRNA regulatory network was closely linked to gametophyte development and male sterility in Ponkan mandarin. The expression profiles of miR156 and miR167 as well as their targets demonstrated their contribution in male sterility in the Ponkan seedless type. This study provides valuable information for better understanding of miRNAs network in plant anther development and lays a foundation to future research on male sterility in citrus and even other species. small RNA and degradome sequencing of seedy ‘Egan No.1’ and its male sterile and seedless mutant ‘Qianyang seedless’
Project description:Seedlessness is an important agronomic trait for citrus, and male sterility (MS) is one main cause of seedless citrus fruit. However, the molecular mechanism of citrus seedlessness remained not well explored. An integrative strategy combining SSH (suppression subtractive hybridization) library with cDNA microarray was employed to study the underlying mechanism of seedlessness of a Ponkan mandarin seedless mutant (Citrus reticulate Blanco). Screening with custom microarray, a total of 279 differentially expressed clones were identified, and 133 unigenes (43 contigs and 90 singletons) were obtained after sequencing. Gene Ontology (GO) distribution showed that the majority of differential genes involved in metabolic process, responded to stimulus and functioned as DNA/RNA binding, catalytic activity and oxidoreductase activity. Expression dynamics of some candidate clones revealed a gene encoding male sterility protein 2 was highly up-regulated, while several transcription factors (TFs) such as AP2/EREBP, MYB, WRKY, NAC and C2C2-GATA zinc-finger domain TFs were specifically down-regulated in the seedless mutant compared with the wild type. Our research highlighted some candidate pathways that participated in the citrus male gametophyte development and could be beneficial for seedless citrus breeding in the future. Flower buds from the seedless citrus mutant and its wild type were collected at four developmental stages: quaring stage (SF, about 20 DBF), medium bud stage (MF, about 10 DBF), flowers at full bloom stage (BF) and young ovaries of 2-3 days after flowering (OV). Total RNA extracted from the mutant and the wild type was hybridized to the array. The hybridization was performed in duplicate by dye swap.