Abstract
Flower induction is an essential stage in walnut (Juglans regia L.) trees, directly affecting yield, yield stability, fruit quality and commodity value. The objective of this study was to identify miRNAs related to female flower induction via high-throughput sequencing and bioinformatics analysis. A total of 123 miRNAs were identified including 51 known miRNAs and 72 novel miRNAs. Differential expression was observed in 19 of the known miRNAs and 34 of the novel miRNAs. Twelve miRNAs were confirmed by RT-qPCR. A total of 1339 target genes were predicted for the differentially expressed miRNAs. The functions of 616 of those target genes had been previously annotated. The target genes of the differentially expressed miRNAs included: (i) floral homeotic protein APETALA 2 (AP2) and ethylene-responsive transcription factor RAP2-7 which were targeted by jre-miRn69; (ii) squamosa promoter-binding protein 1 (SPB1) and various SPLs (squamosa promoter-binding-like protein) which were targeted by jre-miR157a-5p; (iii) various hormone response factors which were targeted by jre-miR160a-5p (ARF18) and jre-miR167a-5p (ARF8) and (iv) transcription factor SCL6 which was targeted by jre-miR171b-3p, jre-miRn46 and jre-miRn49. The KEGG pathway analysis of the target genes indicated that the differentially expressed miRNAs were mainly enriched to ubiquitin mediated proteolysis, RNA degradation and various carbohydrate metabolism pathways. Many miRNAs were detected in J. regia during female flower induction. Some miRNAs (jre-miR157a-5p, jre-miR160a-5p, jre-miR167a-5p, miR171b-3p jre-miRn69 and jre-miRn49) were involved in female flower induction. The results of this experiment will contribute valuable information for further research about the function of miRNAs in flower induction of J. regia and other fruit trees.
Highlights
Walnut (Juglans regia L.) is an economically important nut tree, with more than 7000 years of evolutionary and domestication history in China [1,2]
We constructed three small RNA libraries using female flower buds collected at different stages of flower development: (i) before flower induction (F_1); (ii) during flower induction (F_2); and (iii) after flower induction (F_3)
We identified 72 novel miRNAs and 45 novel miRNA*s which corresponded to 75 precursors
Summary
Walnut (Juglans regia L.) is an economically important nut tree, with more than 7000 years of evolutionary and domestication history in China [1,2]. The development of J. regia flowers begins with flower induction, flower initiation, and flower differentiation during the first growing season and ends with blooming in the second growing season. Flower induction involves the anatomical and morphological transition from vegetative meristems to reproductive meristems [3]. The date, intensity and quality of flower induction and differentiation directly influence the fruit tree’s early fruiting, fruiting stability, fruit quality and commodity value. Flower induction in woody trees is closely related to the time when new shoots stop growing [4]. In J. regia, the induction of female flowers occurs 3 to 7 weeks after medium and short branches cease vegetative growth.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
