Cell number regulator genes in Prunus provide candidate genes for the control of fruit size in sweet and sour cherry

Abstract

Striking increases in fruit size distinguish cultivated descendants from small-fruited wild progenitors for fleshy fruited species such as Solanum lycopersicum (tomato) and Prunus spp. (peach, cherry, plum, and apricot). The first fruit weight gene identified as a result of domestication and selection was the tomato FW2.2 gene. Members of the FW2.2 gene family in corn (Zea mays) have been named CNR (Cell Number Regulator) and two of them exert their effect on organ size by modulating cell number. Due to the critical roles of FW2.2/CNR genes in regulating cell number and organ size, this family provides an excellent source of candidates for fruit size genes in other domesticated species, such as those found in the Prunus genus. A total of 23 FW2.2/CNR family members were identified in the peach genome, spanning the eight Prunus chromosomes. Two of these CNRs were located within confidence intervals of major quantitative trait loci (QTL) previously discovered on linkage groups 2 and 6 in sweet cherry (Prunus avium), named PavCNR12 and PavCNR20, respectively. An analysis of haplotype, sequence, segregation and association with fruit size strongly supports a role of PavCNR12 in the sweet cherry linkage group 2 fruit size QTL, and this QTL is also likely present in sour cherry (P. cerasus). The finding that the increase in fleshy fruit size in both tomato and cherry associated with domestication may be due to changes in members of a common ancestral gene family supports the notion that similar phenotypic changes exhibited by independently domesticated taxa may have a common genetic basis.Electronic supplementary materialThe online version of this article (doi:10.1007/s11032-013-9872-6) contains supplementary material, which is available to authorized users.

QTL mapping of pomological traits in peach and related species breeding germplasm

“…In a protein homology search of cell number regulator (CNR) genes, first performed on the peach reference genome sequence for later localization in cherry, De Franceschi et al (2013) reported four homologs located at *15.6 Mb of G2. The CNR genes modulate cell proliferation in the ovary carpel, as validated in various crop species including tomato, maize, eggplant and peppers (Guo and Simmons 2011).…”

Differences in Physiological Characteristics and Gene Expression Levels in Fruits between Japanese Persimmon (<i>Diospyros kaki</i> Thunb.) ‘Hiratanenashi’ and Its Small Fruit Mutant ‘Totsutanenashi’

“…It was reported that the expression level of Pafw2.2-like was higher in smaller fruits than in normal fruits of 'Hass' in avocado (Cowan et al, 1997;Dehan et al, 2010;Zilkah and Klein, 1987). FW2.2/CNR family genes are known to be associated with the regulation of fruit cell number in tomato (Frary et al, 2000) and sweet cherry (De Franceschi et al, 2013). Although our studies also suggested that the difference in fruit size between HTN and TTN attributed mainly to different cell numbers, the expression levels of FW2.2/CNR family genes did not significantly differ.…”

“…The FW2.2/CNR family of genes controls organ size by modulating cell numbers in other plant species such as avocado (Persea americana Mill. ; Dehan et al, 2010) and sweet cherry (De Franceschi et al, 2013). In avocado, the expression level of Pafw2.2-like was higher in the smaller fruits of 'Hass' trees than in normal fruits (Cowan et al, 1997;Dehan et al, 2010;Zilkah and Klein, 1987).…”

“…In avocado, the expression level of Pafw2.2-like was higher in the smaller fruits of 'Hass' trees than in normal fruits (Cowan et al, 1997;Dehan et al, 2010;Zilkah and Klein, 1987). In sweet cherry, De Franceschi et al (2013) reported that PavCNR12, a CNR gene, is located within the confidence interval of the major fruit size G2 quantitative trait loci, which is postulated to affect fruit size by controlling mesocarp cell numbers , thereby, controlling fruit size (Olmstead et al, 2007). If the fewer cell numbers in TTN fruits lead to the smaller fruit size, then the expression intensities of the FW2.2/CNR family genes between TTN and HTN during the cell division period should be interesting.…”

A standard nomenclature for gene designation in the Rosaceae

“…In tomato, the ARF gene family was independently named by two different research groups, resulting in each gene having two names (Kumar et al 2011;Wu et al 2011). whereon the other hand, in some cases, the same three letter abbreviation has been given to different genes, such as CELL NUMBER REGULATOR (CNR) in cherry (De Franceschi et al 2013) and COLORLESS NON RIPENING (CNR) in tomato (Manning et al 2006). Once a reference genome has become available, the problem can amplify, as independent groups annotate entire gene families.…”