Genetic variability in a Brazilian apple germplasm collection with low chilling requirements

Livia Costa Mariano; Felipe Liss Zchonski; Clandio Medeiros da Silva; Paulo Roberto Da-Silva

doi:10.7717/peerj.6265

Genetic variability in a Brazilian apple germplasm collection with low chilling requirements

PeerJ. 2019 Jan 21:6:e6265. doi: 10.7717/peerj.6265. eCollection 2019.

Authors

Livia Costa Mariano¹, Felipe Liss Zchonski¹, Clandio Medeiros da Silva², Paulo Roberto Da-Silva¹

Affiliations

¹ Plant Genetics and Molecular Biology Laboratory, Universidade Estadual do Centro-Oeste, UNICENTRO, Guarapuava, Paraná, Brazil.
² Instituto Agronômico do Paraná, Londrina, Paraná, Brazil.

Abstract

The apple (Malus domestica Borkh) originally evolved to require temperatures below 7.2 °C for the induction of budding and flowering. In Brazil, breeders have overcome the climate barrier and developed the cultivars Anabela, Julieta, Carícia, and Eva, with low chilling requirements and good yield characteristics. These cultivars are grown in many warmer climate countries in South America, Africa, and the Middle East. The apple germplasm collection that originated these cultivars has several genotypes with pedigrees for a low chilling requirement. Knowledge of the variability and genetic relationships among these genotypes may be useful in the development of superior new cultivars. In this work, we first selected the best ISSR (inter-simple sequence repeat) primers for genetic studies in apple, and then we used the selected primers to evaluate the genetic variability of the apple germplasm collection at the Instituto Agronômico do Paraná. The evaluation of 42 ISSR primers in 10 apple genotypes allowed us to select the best nine primers based on the polymorphic information content (PIC) and resolving power (RP) indexes. The primer selection step was robust since the dendrogram obtained with the nine selected primers was the same as the one obtained using all 26 polymorphic primers. Primer selection using PIC and RP indexes allowed us to save about 60% of time and costs in the genetic variability study. The nine ISSR primers showed high levels of genetic variability in the 60 apple genotypes evaluated. The relevance of the primer selection step is discussed from the perspective of saving time and money in germplasm characterization. The high genetic variability and the genetic relationships among the genotypes are discussed from the perspective of the development of new apple cultivars, mainly aiming for a low chilling requirement that can better adapt to current climatic conditions or those that may arise with global warming.

Keywords: Genetic divergence; ISSR; Inter-simple sequence repeat; Malus; Molecular markers; Pre-breeding.

Grants and funding

This work was supported by the Fundação Araucária de Apoio ao Desenvolvimento Científico e Tecnológico do Estado do Paraná (No. 229/2010). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.