Quantitative and qualitative interspecific genomic differences between the non-model crop trees, Ilex paraguariensis and I. dumosa (Aquifoliaceae)

GOTTLIEB, AM & POGGIO L

Plant Genetic Resources Newsletter

Robert Koebner, CropGen International, UK

Año: 2014 p. 1 - 11

0048-4334

The development of modern approaches for the genetic improvement of the tree crops Ilex paraguariensis (?yerba mate?) and I. dumosa (?yerba señorita?) is halted by the scarcity of basic genetic information. We have characterized both species implementing low-cost methodologies such as Representational Difference Analysis (RDA), Single Strand Conformation Polymorphisms (SSCP), and reverse and direct Dot-Blot filter hybridization assays coupled with thorough bioinformatic characterizations of sequence data. Also, we have estimated the genome size of each species using Flow Cytometry. This paper is a contribution towards the better understanding of the genetic differences between two cultivated species, by generating new quantitative and qualitative genome-level data. From the RDA we isolated a group of non-coding repetitive sequences, tentatively considered as Ilex-specific, which are 1.21 to 39.62-fold more abundant in the I. paraguariensis genome. Another group of repetitive DNA involves retrotransposons, which appear 1.41 to 35.77-fold more abundantly in I. dumosa´s genome. Each species´ genomic DNA showed different performances in the filter hybridizations; while I. paraguariensis showed high intraspecific affinity, I. dumosa exhibited a higher affinity for the genome of the former species (i.e., interspecific). These differences could be based on the occurrence of homologous but slightly divergent repetitive DNAs, highly amplified in I. paraguariensis genome but not in I. dumosa. Additionally, our outcomes suggest that both species´ genomes have less than 80% similarity. Then, for I. paraguariensis we estimated a genome size of 1670 Mbp and of 1848 Mbp for I. dumosa, values that are reported here for the first time.