Revolutionizing peach breeding: Pioneering peach-almond introgression lines unlock genetic diversity and stress resistance

Peaches, with their low genetic variability, stand in contrast to their diverse relative, the almond. While both are inter-compatible, producing fertile hybrids, almonds offer a rich source of new genes potentially beneficial for peach, especially in conferring stress tolerance. Introgression Line (IL) collections, which incorporate fragments of a donor genome into a recurrent genome, have been invaluable in plant breeding and genetics, aiding in the analysis of complex traits and gene interactions. This approach, however, is challenging in tree species like peach due to long intergeneration period. Recent research has focused on the crossbreeding of peach and almond, utilizing Marker-Assisted Introgression (MAI) to expedite the generation of ILs. This method has already yielded peach lines with almond genes for disease resistance, demonstrating the potential for introducing almond genetic diversity into peach breeding programs. The current challenge lies in effectively integrating and analyzing these new genetic elements to enhance  adaptability and resistence of peach.

In March 2022, Horticulture Research published a research article entitled by “Construction of a collection of introgression lines of “Texas” almond DNA fragments in the “Earlygold” peach genetic background”. 

This research focused on developing a collection of peach-almond introgression lines (ILs), combining a single fragment of almond (cv. Texas) into a peach background (cv. Earlygold). Using a total of 8,467 fruits from various generations of the almond × peach cross, the researchers constructed the IL collection by initially using simple-sequence repeat markers and later employing the 18 k peach SNP chip for selection. The research yielded a collection of 39 heterozygous ILs covering 99% of the genome with a small DNA fragment of almond and 28 homozygous ILs covering 83% of the genome. Segregation analysis in the “Earlygold” background was also conducted using the SNP chip, revealing large genome regions without segregating markers. As a proof of concept, four major genes and four quantitative characters were examined in the selected ILs, major genes and quantitative traits were examined in the IL collection, and results were consistent with previous genetic information. Traits such as juiciness, blood flesh, resistance to powdery mildew, and maturity date were consistent with expectations, and QTLs were identified for fruit weight, soluble solid contents, and petiole length.

Overall, as the first of its kind in a woody perennial species, this IL collection represents a culmination of 15 years of research and breeding across three backcross generations. Its significance lies not just in enriching the genetic diversity of peaches but also in offering insights into key aspects of species divergence, such as differences in fruit morphology and adaptation to abiotic stress.

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References

Authors

Naveen Kalluri¹, Octávio Serra², José Manuel Donoso³, Roger Picañol⁴, Werner Howad^1,5, Iban Eduardo^1,5,* and Pere Arús^1,5,*

Affiliations

¹Centre for Research in Agricultural Genomics (CRAG) CSIC-IRTA-UAB-UB, Campus UAB, Edifici CRAG, Cerdanyola del Vallès (Bellaterra), 08193 Barcelona, Spain

²Instituto Nacional de Investigação Agrária e Veterinária, I.P., Banco Português de Germoplasma Vegetal (BPGV), Braga, Portugal

³Instituto de Investigaciones Agropecuarias (INIA), Centro Regional de Investigación Rayentué, Av. Salamanca s/n Sector Los Choapinos, Rengo 2940000, Chile

⁴Rijk Zwaan Ibérica S.A. Finca La Marina-PJ Lo Contreras 30395, La Puebla|Cartagena (Murcia), Spain

⁵IRTA, Campus UAB, Edifici CRAG, Cerdanyola del Vallès (Bellaterra), 08193 Barcelona, Spain

About Iban Eduardo & Pere Arús

Iban Eduardo: He is a researcher at IRTA, and he is in the research group of Rosaceae genetics and genomics.

Pere Arús: He is a researcher at IRTA, and he is in the research group of Rosaceae genetics and genomics.