Varietal variation and chromosome behaviour during meiosis in Solanum tuberosum

Abstract

Naturally occurring autopolyploid species, such as the autotetraploid potato Solanum tuberosum, face a variety of challenges during meiosis. These include proper pairing, recombination and correct segregation of multiple homologous chromosomes, which can form complex multivalent configurations at metaphase I, and in turn alter allelic segregation ratios through double reduction. Here, we present a reference map of meiotic stages in diploid and tetraploid S. tuberosum using fluorescence in situ hybridisation (FISH) to differentiate individual meiotic chromosomes 1 and 2. A diploid-like behaviour at metaphase I involving bivalent configurations was predominant in all three tetraploid varieties. The crossover frequency per bivalent was significantly reduced in the tetraploids compared with a diploid variety, which likely indicates meiotic adaptation to the autotetraploid state. Nevertheless, bivalents were accompanied by a substantial frequency of multivalents, which varied by variety and by chromosome (7–48%). We identified possible sites of synaptic partner switching, leading to multivalent formation, and found potential defects in the polymerisation and/or maintenance of the synaptonemal complex in tetraploids. These findings demonstrate the rise of S. tuberosum as a model for autotetraploid meiotic recombination research and highlight constraints on meiotic chromosome configurations and chiasma frequencies as an important feature of an evolved autotetraploid meiosis.

The recombination landscape and multiple QTL mapping in a Solanum tuberosum cv. ‘Atlantic’-derived F1 population

“…2 ). These results are in accordance with recent findings published by Choudhary et al ( 2020 ). These authors presented a map of meiotic stages in S. tuberosum in one diploid and three tetraploid varieties using fluorescence in situ hybridization (FISH).…”

“…They concluded that bivalent chromosome associations are the most common in metaphase I of tetraploid potatoes. Likewise, the broad range of multivalent signature rates observed in our study (2.2~39.2%) was also observed by Choudhary et al ( 2020 ) (7~48%). Similarly, as their observations differed depending on variety and chromosome, in our study, the variation occurred by parents and by linkage groups.…”

The recombination landscape and multiple QTL mapping in aSolanum tuberosumcv. ‘Atlantic’-derived F1population

“…In addition, most of the parental meiotic configurations based on the B2721 population were inferred as bivalents (62.3% on average) since they involved two homologs exchanging segments during the metaphase I (Figure 2). These results are in accordance with recent findings published by Choudhary et al . (2020).…”

“…They concluded that bivalent chromosome associations are the most common in metaphase I of tetraploid potatoes. Likewise, the broad range of multivalent signature rates observed in our study (2.2∼39.2%) was also observed by Choudhary et al . (2020) (7∼48%).…”

The Unique Existence of Chromosomal Abnormalities in Polyploidy Plants

“…The convergent tasks detected (other meiotic pathway, chromosome arrangement or remodeling, ABA cues and ion transport) offer initially insights into the noticeable challenges related to polyploidization. Another example, investigating the meiosis of autotetraploid potato S. tuberosum revealed variety of challenges in correct segregation and recombination of multiple homologous chromosomes that constraints on meiotic chromosomal configuration [2].…”