Developmental Transcriptome Profiling Uncovered Carbon Signaling Genes Associated with Almond fruit drop

Almond is one of the most featured nut crops owing to its high nutritional value. However, due to three different waves of flower and fruitlet drop, fruit drop is a major concern for growers. In this study, we carried out a time-course transcriptome analysis to investigate gene expression difference between normal and abnormal fruitlet development. By de novo assembly analysis, we identified 33,577 unigenes and provided their functional annotations. In total, we identified 8,676 differentially expressed genes and observed the most apparent difference between normal and abnormal fruits at 12 and 17 day after flowering. Their biological functions were enriched in carbon metabolism, carbon fixation in photosynthetic organisms and plant hormone signal transduction. RT-qPCR validated the expression pattern of 15 representative genes, including glycosyltransferase like family 2, MYB39, IAA13, gibberellin-regulated protein 11-like and POD44, which confirmed the reliability of our transcriptome data. This study provides an insight into the association between abnormal fruit development and carbohydrate signaling from the early developmental stages and could be served as useful information for understanding the regulatory mechanism related to almond fruit drop. Overall design: Gene expression profiling analysis in normal and abnormal fruitlets and identification of differentially expressed genes at different developmental stages were performed