A Set of 20 New SSR Markers Developed and Evaluated in Mandevilla Lindl.

Abstract

Abstract:Mandevilla is an ornamental crop with a bright future worldwide because of its high commercial acceptance and added value. However, as with most ornamental species, there are few molecular tools to support cultivar breeding and innovation. In this work, we report the development and analysis of 20 new Simple Sequence Repeat (SSR) markers in Mandevilla. Microsatellites were isolated from two enriched small-insert genomic libraries of Mandevilla × amabilis. The diversity parameters estimated after their amplification in a group of 11 commercial genotypes illustrate the effect of two opposite drifts: the high relatedness of cultivars belonging to the same commercial group and the high divergence of other cultivars, especially M. × amabilis. Based on their different band patterns, six genotypes were uniquely distinguished, and two groups of sport mutations remained undistinguishable. The amplification of the SSRs in three wild species suggested the existence of unexploited diversity available to be introgressed into the commercial pool. This is the first report of available microsatellites in Mandevilla. The development process has provided some clues concerning the genome structure of the species, and the SSRs obtained will help to create new products and to protect existing and upcoming plant innovations.

First genomic insights into the Mandevilla genus

“…Based on the Botstein et al (1980) classification, the majority of SSRs (18 loci, 78%) were highly polymorphic, with PIC values always higher than 0.5. Moreover, it is worth pointing out that the overall PIC of this new set of SSR panels was demonstrated to be higher than that of the only other SSR set available for the Mandevilla genus ( Oder et al, 2016 ). In this latter study, Oder et al (2016) tested a set of 20 SSRs on 11 accessions belonging to the Mandevilla genus, and their PIC values oscillated from 0.08 to 0.76, and the average was 0.48 ( Table 3 ).…”

“…Several Apocynaceae family members are highly reputed in traditional medicine and have been extensively investigated for a wide range of curative properties, including antioxidant ( Naidoo et al, 2021 ), anti-inflammatory ( Bhadane et al, 2018 ), anticancer ( Wen et al, 2016 ), and antimicrobial ( Anand et al, 2020 ) activities. Mandevilla instead represents a leading product of the world ornamental scenario, as demonstrated by the growing number of new varieties that literally flood the market every year ( Oder et al, 2016 ). Despite this, very few studies have been accomplished in this species, and many biological questions remain unsolved.…”

“…Almost 100 years later, a second classification ( Woodson, 1933 ) revolutionized the genus organization: Dipladenia spp., along with seven other genera, all of which were incorporated in the Mandevilla genus. Although Dipladenia is currently generally considered a historical synonym of Mandevilla, a recent study demonstrated that the Dipladenia group clustered apart from the Mandevilla group ( Oder et al, 2016 ). Moreover, some breeding companies are still tied to tradition, and they continue selling their products, clearly distinguishing Mandevilla from Dipladenia ( Flowers, 2021 ).…”

“…What makes this genus challenging for taxonomists is the remarkable morphological variation observed among and within species due to a continuous process of adaptation to a plethora of different geographical environments ( Simões et al, 2006 ). Another level of complexity is given by the fact that most of the genotypes available are interspecific hybrids, characterized by complex genealogies ( Oder et al, 2016 ) and possibly even by different levels of ploidy or by unbalanced numbers of chromosomes. Additionally, Mandevilla is an understudied species: no information about DNA content ( c -value) and ploidy levels is available in the scientific literature.…”

“…Taxonomic classification and phylogenetic relationships are not the only lacking aspects; molecular markers, with one exception ( Oder et al, 2016 ), have never been exploited in these species, suggesting that despite the huge turnover, breeding schemes are still planned almost exclusively on a phenotypic basis. Historically, marker-assisted breeding in ornamental species has been delayed compared to crop species for several reasons, such as reduced economic importance, genome complexity (i.e., ornamental plants have genomes that are usually larger and polyploid) and methods of propagation (i.e., ornamental plants are mainly vegetatively propagated).…”