Identification and Expression Analysis of Fruit Weight Loci in Italian Plum (Prunus domestica L.) Varieties

Abstract Background Increasing global food demand is one of the greatest challenges of modern agricultural sciences. A crucial agronomic trait for plant breeding programs to increase yield production is fruit weight (FW). Although two major FW quantitative loci (FW2.2 and FW11.3) have been isolated and studied in several crop species, much still remains to be done for stone fruit trees, such as plum ( Prunus domestica L.). Results In this study, six Italian plum varieties were evaluated for fruit size-related traits and genotypic characteristics. Data brought out that Pappacona varieties were a good model for identifying molecular markers associated with fruit size. Using the recently released plum genome assembly , 73 cell number regulator (CNR) and 42 cell size regulator (CSR) genes were finely annotated. Two FW2.2 (PdCNR-1 and PdCNR-2) and one FW11.3 (PdCSR-1) homologs were identified. To provide a first transcriptional characterization, PdCNR-1, PdCNR-2, and PdCSR-1 were analyzed by real-time PCR. PdCNR-1 and PdCSR-1 expression patterns suggested a potential novel regulatory pathway in plum, which might contribute to variations in fruit size and weight. Conclusions A better understanding of plum FW quantitative loci will promote progress in both basic research and practical breeding activities aiming to select large-fruited varieties.