Genetic and phenotypic analyses reveal major quantitative loci associated to fruit size and shape traits in a non-flat peach collection (P. persica L. Batsch)

Fruit size and shape are critical agronomical and pomological attributes and prime targets in peach breeding programs. Apart from the flat peach type, a Mendelian trait well-characterized at the genetic level, ample diversity of fruit size and shapes is present across peach germplasms. Nevertheless, knowledge of the underlying genomic loci remains limited. In this work, fruit size and shape were assessed in a collection of non-flat peach accessions and selections, under controlled fruit load conditions. The architecture of these traits was then dissected by combining association and linkage mapping, revealing a major locus on the proximal end of chromosome 6 (qSHL/Fs6.1) explaining a large proportion of phenotypic variability for longitudinal shape and also affecting fruit size. A second major locus for fruit longitudinal shape (qSHL5.1), probably also affecting fruit size, was found co-localizing at locus G, suggesting pleiotropic effects of peach/nectarine traits. An additional QTL for fruit longitudinal shape (qSHL6.2) was identified in the distal end of chromosome 6 in a cross with an ornamental double-flower peach and co-localized with the Di2 locus, controlling flower morphology. Besides assisting breeding activities, knowledge of loci controlling fruit size and shape paves the way for more in-depth studies aimed at the identification of underlying genetic variant(s).

Phenotypic, Genetic, and Epigenetic Variation among Diverse Sweet Cherry Gene Pools

Sweet cherry germplasm contains a high variety of phenotypes which are associated with fruit size and shape as well as sugar content, etc. High phenotypic variation can be a result of genetic or epigenetic diversity that may interact through time. Recent studies have provided evidence that besides allelic variation, epiallelic variation can establish new heritable phenotypes. Herein we conducted a genetic and an epigenetic study (using amplified fragment length polymorphism (AFLP) and methylation-sensitive amplified polymorphism (MSAP) markers, respectively), accompanied by phenotypic traits correlation analysis in sweet cherry gene pools. The mean genetic diversity was greater than the epigenetic diversity (hgen = 0.193; hepi = 0.185), while no significant relationship was found between genetic and epigenetic distance according to a Mantel test. Furthermore, according to correlation analyses our results provided evidence that epigenetic diversity in predefined populations of sweet cherry had a stronger impact on phenotypic traits than their rich genetic diversity.

The fruit metric trait characterization of scarlet eggplant using the high-throughput tomato analyzer software

Scarlet eggplant (Solanum aethiopicum [L.]) is an indigenous, underutilized fruit vegetable in Africa. Preference for fruit shape and size is high among growers and consumers. Fruit metric traits are important for yield improvement. Fruit metric descriptors are important contributors to variation, phenotypic and genotypic variation, and heritability. However, the measurement of these traits is cumbersome and subjective. Forty-three accessions were evaluated in 2016 and 2017. At maturity, 5 fruits were randomly harvested from each accession, digitalized and processed using the Tomato Analyzer software. Sixteen fruit metric traits were automatically generated and submitted for analysis of variance and multivariate analysis. The accessions differed over fruit size and shape due to genetic make-up. Fruit metric trait variation among S. aethiopicum groups was less influenced by the environment. The cv. Gilo group has oblong fruits, the cv. Shum group fruits are circular and ovoid; the cv. Kumba group fruits are less circular, lobed and flattened. AE/113 (C3), FUO 1 (C1) and FUO 5 (C2) Gilo groups are promising for fruit size. There were phenotypic plasticity and overlapping for fruit metric traits between the Gilo and Shum groups due to a common genome. The Tomato Analyzer software was able to discriminate accessions based on fruit phenomic traits, and the information could be used to establish commonalities between groups.

A preliminary evaluation of the effects of pollinator enhancement and gibberellins on the fruit set and fruit shape of ‘Conference’ pears – Short Communication

‘Conference’ (Pyrus communis L.) is a self-incompatible cultivar, although it can also set fruit parthenocarpically. Stimulating parthenocarpy through gibberellin (GA) applications increases the fruit set, but it may also negatively affect the fruit size and shape. The aim of this study was to investigate the effects of a bumblebee (BB) amendment in combination with a GA treatment on the fruit set and fruit shape of ‘Conference’ pears. In the first experiment, we applied three treatments (GA, GA + BB & control) in a ‘Conference’ monoculture. In the second experiment, we applied two treatments (GA & GA + BB) in a ‘Conference’ orchard inter-planted with ‘Concorde’ as pollinizer trees. Both experiments showed that the GA application and bumblebee supplementation did not affect the fruit set. However, the BB treatment resulted in significantly higher amounts of normally shaped pears. Trees closer to the bumblebee hive had more normal shaped pears than trees further away.

Commodity and consumer qualities of fruits of plum cultivars from the RRIFCB (VNIISPK) gene pool

Relevance. One of the most important directions in the breeding and variety study of fruits, in particular domestic plum European, is the breeding of cultivars with high commercial and consumer qualities of fruits. In this regard, the assessment of some commercial and consumer qualities of fruits in plum cultivars of the RRIFCB gene pool was of great practical and scientific interest. Material and methods. As objects of research, we used 8 plum cultivars of the RRIFCB gene pool and a control cultivar of the RRIFCB breeding Bolkhovchanka. The studies were carried out on the basis of the laboratory of breeding and variety study of stone fruit crops of RRIFCB in 2015-2019. Determination of color, shape, average weight, taste, size of fruit, size and shape of the stone, density of pulp, separation and length of the stalk, color of the juice were carried out in accordance with the "Program and methodology for the variety study of stone fruit crops" and "Pomology". Results. Most of the studied plum cultivars from the gene pool of the Russian Research Institute for Fruit Crops Breeding have valuable commercial and consumer qualities of fruits, which will allow them to be used in further breeding for this trait. Cultivars Californiyskaya krupnaya, Zarechnaya rannyaya, Volgogradskaya can be recommended for further use in breeding as sources of high fruit mass. Cultivars Californiyskaya krupnaya and Bolkhovchanka can be recommended for further use in breeding as sources of high pulp content in fruits and fruit sizes. On the basis of the tasting assessment of the fresh fruits, the fruits of the cultivar Volgogradskaya stood out positively.

Cucumber Fruit Size and Shape Variations Explored from the Aspects of Morphology, Histology, and Endogenous Hormones

Fruit size and shape are important qualities and yield traits in cucumber (Cucumis sativus L.), but the factors that influence fruit size and shape remain to be explored. In this study, we investigated the dynamic changes of fruit size and shape from the aspects of morphology, cellular levels and endogenous hormones for nine typical cucumber inbred lines. The results show that fruit length had a strong positive correlation to the cell number in the longitudinal section of fruit throughout the four stages of 0, 6, 12, and 30 DAA (days after anthesis). However, the significant negative correlations were found between fruit length and the fruit cell size at 12 and 30 DAA. Furthermore, fruit diameter was positively correlated to the cell number in the cross section at all the investigated fruit growth stages. The indole-3-acetic acid (IAA) content showed significant positive correlations to the fruit length at all fruit growth stages of −6, −3, 0, 3, 6, 9 and 12 DAA, but IAA content and fruit diameter showed significant negative correlations for all the stages except for at −6 DAA. The trans-zeatin riboside (tZR), zeatin (ZT), gibberellic acid (GA3) and jasmonic acid (JA) content had a positive or negative correlation with fruit length or diameter only at certain stages. Neither fruit length nor diameter had significant correlations to abscisic acid (ABA) content. These results indicate that variations in fruit size and shape of different cucumber inbred lines mainly result from the differences in fruit cell number and endogenous IAA content. The present work is the first to propose cucumber fruit size and shape changes from the combined aspects of morphology, cellular levels, and endogenous hormones.

Decreased number of locules and pericarp cell layers underlie smaller and ovoid fruit in tomato smaller fruit (sf) mutant

Fruit size and shape are the primary criteria for domestication and improvement of tomato. The varying sizes and shapes of tomato fruit further signify their importance as agronomic traits. Here, we characterized a tomato mutant, smaller fruit (sf), which bears relatively small and ovoid fruits compared with the large and flat fruits of the wild-type (WT). Phenotypic measurements and histological analyses revealed that fruit diameter but not fruit length of the sf mutant decreased compared with that of the WT. This phenotypic change was attributed to significant decreases in locule number and pericarp cell layers in a transverse direction, which resulted in the transition of fruit shape from flat in the WT to ovoid in sf. Comparison of the transcriptomes of ovaries of sf with the WT using RNA-Seq identified 2596 differentially expressed genes, in which 1737 genes significantly were up-regulated and 859 genes were dramatically down-regulated in the sf ovary. Further analyses confirmed that some genes, such as CRCa, CNRs, CYCs, WUS, SUNs, OFRs, CDKs, participate in regulation of fruit size and shape of sf mutant. Thus, our study adds a new genetic resource regarding fruit size and shape of tomato, and provides a valuable basis for understanding molecular regulation of small and ovoid fruit of the sf mutant.