Frost tolerance and adventitious rooting in hybrid clones of Eucalyptus

AYALA, P.G.; VIVAS, VLL.; SANSBERRO, P.A.; HARRAND, L.; MARGARIT, E.; OBERSCHELP, G.P.J.

Rosario

Congreso; XXXIV Argentinian Meeting of Plant Physiology - SAFV; 2023

SAFV

Frost tolerance and adventitious rooting in hybrid clones of Eucalyptus (1) Ayala, P.G.; (1) Vivas, V.L.; (2,3) Sansberro, P.A.; (1) Harrand, L.; (4)Margarit, E.; (1) Oberschelp, G.P.J..(1) Instituto Nacional de Tecnología Agropecuaria (INTA) Ruta 22 y vías del ferrocarril, CP E3200AQK, Estación Yuquerí, Concordia, Entre Ríos, Argentina; (2) Laboratorio de Biotecnología Aplicada y Genómica Funcional. Instituto de Botánica del Nordeste (CONICET); (3) Facultad de Ciencias Agrarias (UNNE). Sgto. Cabral 2131. W3402BKG, Corrientes, Argentina. (4) Centro de Estudios Fotosintéticos y Bioquímicos (CEFOBI-CONICET). Suipacha 570, Rosario, Santa FeEmail*: ayala.paula@inta.gob.ar Cultivated eucalyptus species are characterized by high productivity. However, the vast majority of tropical and subtropical species are sensitive to frost, and those that are more tolerant are difficult to propagate. Therefore, the development of genotypes with both traits is of great interest for forest breeding. In this work, the tolerance to freezing stress and adventitious rooting of hybrid genotypes of Eucalyptus benthamii x E. camaldulensis subsp. camaldulensis (BCC) and E. benthamii x E. camaldulensis subsp. acuta (BCP), E. benthamii (EB), E. camaldulensis subsp. camaldulensis (ECC) and E. camaldulensis subsp. acuta (ECP) as parental species, and E. grandis (EG) as a control. Leaf discs of each genotype were sampled and temperature ramps down to -3°C were applied to evaluate the percentage of electrolyte leakage by freezing (EL). Mini-cuttings were collected from the same plant material, then conditioned and transferred to the rooting module to evaluate rooting after 30 days. Evaluations were made twice, in spring and in autumn.Overall, a lower EL was observed in autumn (25.6% rel. to EG) compared to spring (45.7%), indicating a greater tolerance to cold in autumn due to acclimation. Some hybrid genotypes showed lower EL values in both seasons, indicating a higher basal tolerance to cold. Still, although the rooting of mini-cuttings was similar on average in both seasons, it decreased notably in autumn for EB, and increased for BCC hybrids and EG. However, rooting was lower in these hybrids than in their E. camaldulensis parents. Apart from the main trends, a large variability in responses was observed among the hybrid genotypes, identifying individuals with high tolerance to frost tolerance and rooting ability.These results suggest the potential of these hybrid combinations. Furthermore, it represents a starting point for metabolomics and proteomics studies, which will help to elucidate the relationship between cold tolerance and adventitious rooting ability.Keywords: Breeding, cold acclimation, freezing, rooting