RNA‐Seq analysis unveils gene regulation of fruit size cooperatively determined by velocity and duration of fruit swelling in peach

Abstract

Fruit swelling determines fruit size and usually occurs in two distinct time periods in peach. However, little is known about the gene regulation of fruit swelling. In this study, measurements of longitudinal and transverse diameters in developing and ripening peach fruits unveiled two periods of fruit swelling: the first swelling ends at approximately 65 days after flower blooming (DAFB) and the second swelling starts at approximately 75 DAFB. Comparisons of diameters sizes and development periods among cultivars and accessions revealed a cooperative regulation of swelling velocity and swelling duration, which leads to final determination of fruit size. Furthermore, RNA-sequencing was conducted for fruits at the initial swelling, non-swelling interval between the two swellings (hereafter, 'the interval'), second swelling and ripening stages. A total of 110 and 128 differentially expressed genes were screened from fruits in the first and second swelling, respectively. Besides, the nine most differentially expressed genes located within the reported quantitative trait locations (QTLs) of fruit size in peach were detected in both the first and second swelling stages. Those genes have been reported to be involved in mediating cell size, which indicates the occurrence of both cell proliferation and cell expansion in each of the two major periods of fruit swelling. In addition, a potential gene regulation network is proposed herein and could be used to elucidate the molecular mechanism of peach fruit swellings mediated by multiple key genes.

Regulation of Fruit Growth in a Peach Slow Ripening Phenotype

“…Before the description of SR, the study of peach fruit size was restricted to the combination of RNA-Seq and QTL mapping. These approaches have been successfully used to determine critical genes for anthocyanin biosynthesis, stone adhesion, fleshy melting, and fruit swelling [25,26]. Fruit swelling has been related to fruit growth by linking nine highly transcribed genes, located within the QTLs for peach fruit size [27][28][29][30], to the swelling process [25].…”

The NAM/ATAF1/2/CUC2 transcription factor PpNAC.A59 enhances PpERF.A16 expression to promote ethylene biosynthesis during peach fruit ripening

“…Baixianglu fruit presents a semifreestone melting flesh phenotype, and the fruits of the other ten peach cultivars present a clingstone melting flesh phenotype. Based on the dynamic investigation of fruit development and ripening 71 , the fruits of cv. Xiahui No.…”

Comparative transcriptome analyses of fruit development among pears, peaches, and strawberries provide new insights into single sigmoid patterns

“…In a previous study, bHLH was defined as the upstream factor regulating cell expansion-related genes in peaches [13]. In this study, four bHLH genes, bHLH3 To investigate the role of the four bHLH transcription factors (TFs) on the expression of cell expansion-related genes, full-length sequences of the four bHLH genes were amplified and inserted into pSAK277 as effectors.…”

“…The distinction between single and double sigmoid patterns is whether a slow-growth period occurs during fruit enlargement. A previous study reported that cooperation between the velocity and duration of fruit swelling determines fruit size [13], which is determined by both cell number and size [14][15][16]. Currently, little is known about the genes that control fruit size, with the exception of genes involved in the cell cycle, cell wall metabolism, cytochrome, and ubiquitin [13,17,18].…”

“…A previous study reported that cooperation between the velocity and duration of fruit swelling determines fruit size [13], which is determined by both cell number and size [14][15][16]. Currently, little is known about the genes that control fruit size, with the exception of genes involved in the cell cycle, cell wall metabolism, cytochrome, and ubiquitin [13,17,18]. Specifically, cyclin, RNA polymerase II transcription, and mitogen-activated protein kinase kinase kinase are involved in the cell cycle [19][20][21], xyloglucan galactosyltransferase, glycosyltransferase, cellulose synthase, β-galactosidase, and microtubule-associated proteins are associated with cell wall metabolism [22][23][24][25], and transcription factors, including basic region/leucine zipper motif (bZIP) [26], NAM/ATAF1/2/CUC2 (NAC) [27], v-myb avian myeloblastosis viral oncogene homolog (MYB) [28], basic/helix-loop-helix (bHLH) [29], and WRKY [30], are components of the fruit size regulation network.…”