The creation of green areas within urban centers was born as a response to profoundly different problems, such as the demographic increase and the progressive urbanization of landscapes. Moreover, up to date, the genetics of plants has not been considered for urban contexts. The purpose of this review is to discuss the state of the art and the advantages in planning genetic improvement for plants for urban destinations, also providing technical information, that may contribute in a concrete way. Firstly, recent genomic sources and their potential contribution to breeding programs are discussed. Then, dividing the urban scenarios into four macro areas (i.e., urban/metropolitan parks, urban gardens, road verges and roofs/terraces/balconies), we described the role of genetics in the adaptability and sustainability of plants in these different contexts. In addition, we analyzed the genetic traits plants need to provide services for a city environment and population (e.g., pollution reduction, biodiversity conservation, soil stability, and food production).

Lantana camara L. is sold worldwide for ornamental purposes, although it is also characterized by high invasiveness potential. Genetic and molecular data available for L. camara are still poor, and breeding is performed through conventional methods. This study focused on a molecular genotyping analysis through the ddRADseq method on an experimental collection of lantana clonal lines to evaluate the potential of molecular techniques in performing marker-assisted breeding, in favour of variety registration and in guaranteeing plant variety protection for the species. Although high genetic uniformity was observed in the population, a unique molecular profile was assigned to every line, indicating the effectiveness of the approach used. Interestingly, low degrees of heterozygosity were observed. In addition, the possibility of inferring ploidy levels through SNP profiles was assessed since it would avoid the necessity of previous biological knowledge and the use of fresh materials. Ploidy analysis is of high interest for lantana breeding to obtain less invasive triploids. Flow cytometry and chromosome counting were used for inference assessment. An nQuack framework provided correct results for the majority of the clonal lines, confirming its effectiveness. These findings encourage the adoption of molecular systems to help breed minor species such as L. camara.

Molecular genotyping is a key factor for plant breeding programming and Plant Variety Protection. However, its potential still remains to be elucidated when considering ornamental plants like Petunia × hybrida. In this study, a Petunia breeding clone collection, including sister line groups, was genotyped through double digest Restriction-site Associated DNA sequencing (ddRADseq), and its genetic diversity and structure were studied. In addition to estimate the high genetic similarity observed among sister lines, this approach allowed the unique discrimination of each clone too. Molecular results agreed with genealogy data, assessing genotyping effectiveness. In addition, the minimal number of variants able to correctly genotype the population was investigated. The variant number could be reduced to a hundred with minor adjustments in genotyping results. Moreover, analysis of the chromosomal distribution of variants revealed a predominant accumulation in distal regions. Eventually, genetic analyses were repeated considering only variants located in coding sequences and results were in agreement with what previously observed, disclosing the potential of the expressed regions for genotyping purposes. Our findings encourage the adoption of high-throughput and cost-effective sequencing techniques for plant genotyping, to enhance the technological advancement of breeding programs, in particular for ornamental species.

Molecular genotyping is a key factor for plant breeding programming and plant variety protection (PVP). However, its potential still remains to be elucidated when considering ornamental plants like Petunia × hybrida. In this study, a petunia breeding clone collection, including sister line groups, was genotyped through double digest Restriction-site Associated DNA sequencing (ddRADseq), and its genetic diversity and structure were studied. In addition to estimating the high genetic similarity observed among sister lines, this approach allowed the unique discrimination of each clone too. Molecular results agreed with genealogy data, supporting the assessment of genotyping effectiveness. In addition, the minimal number of variants able to uniquely discriminate and/or correctly cluster the experimental lines was investigated. The loci number could be reduced to eight to achieve line discrimination, and a method to identify the specific variant sets is presented. Conversely, to preserve the original clustering with minor adjustments, one hundred loci were required and were obtained through minor allele frequency (MAF) filtering. Moreover, analysis of the chromosomal distribution of variants revealed a predominant accumulation in distal regions. Genetic analyses were repeated considering only variants located in coding sequences and results were in agreement with what previously observed, disclosing the potential of the expressed regions for genotyping purposes. Eventually, the applied approach enabled the investigation of SNPs within genes putatively involved in traits of interest. Our findings encourage the adoption of high-throughput and cost-effective sequencing techniques for petunia genotyping aimed at achieving PVP, supporting new variety registration, and developing marker-assisted breeding (MAB) and marker-assisted selection (MAS) strategies.