Microsporogenesis and meiotic abnormalities in different ‘Oblačinska’ sour cherry (Prunus cerasus L.) clones

Abstract

The Oblačinska sour cherry (Prunus cerasus) is a mixture of different clones with similar tree and fruit characteristics that is indigenous to and widely planted in commercial orchards in Serbia. Sour cherry, including Oblačinska sour cherry clones, exhibits irregular meiosis which may contribute to low fruit set in some selections. The goal of this study was to examine the process of microsporogenesis and to determine if meiosis and its anomalies effect the in vitro pollen germination and pollen tube length in four 'Oblačinska' sour cherry clones that differ in fruit set and yields. All clones displayed varying degrees of chromosomal abnormalities in all meiosis sub-phases. The abnormalities became evident from late pachytene with more than half of the pollen mother cells (PMC) showing abnormal conjugation of chromosomes in metaphase I. The lowest number of PMCs with laggards was in clone III/9 and the highest in clone XIII/1. In second division, the univalent and multivalent association was observed at metaphase-II, the lagging and stickiness in anaphase-II, and the phenomenon persisted up to the microspore stage. In all four 'Oblačinska' clones, PMCs exhibited cytomixis phenomena, however, it was only observed in the second experimental year. Cytomixis differed among the four clones but was equally frequent in all stages of meiosis. The syncytia formed, most often consisted of 2-3 PMCs that were at the same phase of meiosis, and exhibited common cytoplasm and occasionally nuclear fusion. In vitro pollen germination and pollen tube length significantly differed between the clones. Most probably abnormalities during meiosis, regardless of the good results of pollen germination, influenced the reduced potential clones XI/3 and XIII/1.

A chromosome-scale assembly for tetraploid sour cherry (Prunus cerasusL.) ‘Montmorency’ identifies three distinct ancestralPrunusgenomes

“…Still, given these results and speculations, it would be reasonable to suggest sour cherry exemplifies the behavior of a neopolyploid actively undergoing the process of diploidization. Cytological and genetic data is consistent with a neopolyploid as irregular meiosis visualized as trivalents and quadrivalents is documented in several sour cherry genotypes (10,68), and genetic data indicates that although disomic inheritance is more common, tetrasomic inheritance has also been observed (9,11,71). Such events can result in aneuploid gametes, endosperm imbalance, embryo abortion, and unsuccessful seed and fruit development.…”

“…If the A and A’ chromosomes preferentially pair, crossing over will result in a patchwork of regions exchanged between these two homoeologous chromosome sets. Additionally, cytological analysis of meiotic pairing for ‘Montmorency’ shows lack of complete bivalent pairing: quadrivalents, trivalents and univalents occur (10,68). Segregation data support primarily subgenome pairing (A with A’ and B with B); however genetic results are consistent with occasional homoeologous pairing (5,11).…”

Genome of tetraploid sour cherry (Prunus cerasus L.) ‘Montmorency’ identifies three distinct ancestral Prunus genomes

“…Still, given these results and speculations, it would be reasonable to suggest sour cherry exhibits the behavior of a neopolyploid actively undergoing the process of diploidization. Cytological and genetic data are consistent with a neopolyploid as irregular meiosis visualized as trivalents and quadrivalents is documented in several sour cherry genotypes, and genetic data indicate that although disomic inheritance is more common, tetrasomic inheritance also occurs [ 9 , 15 , 16 , 74 , 78 ]. Such events can result in aneuploid gametes, endosperm imbalance, embryo abortion, and unsuccessful seed and fruit development.…”

“…If the A and A' chromosomes preferentially pair, crossing over will result in a patchwork of regions exchanged between these two homoeologous genomes. Additionally, cytological analysis of meiotic pairing for ‘Montmorency’ shows lack of complete bivalent pairing: quadrivalents, trivalents, and univalents occur [ 15 , 74 ]. Segregation data support primarily “homologous” pairing (A with A' and B with B); however genetic results are consistent with occasional homoeologous pairing [ 5 , 16 ].…”

The effect of genotype and temperature interaction on pollen performance in the pistils of autochthonous sour cherry cultivar ‘Feketićka’

“…The opposite tendencies manifested in pollen germination in vitro by years are directly associated with the regularity in microsporogenesis. In autochthonous sour cherry cultivar 'Oblačinska', pollen germination in vitro positively correlated with microsporogenesis regularity (Fotirić Akšić et al, 2016) and was strongly influenced by the genotype (Fotirić Akšić et al, 2017).…”