Physiological and morphological responses of Prunus species with different degree of tolerance to long-term root hypoxia

• ‘Mariana M2624′, a plum based rootstock, is the most tolerant genotype to root hypoxia.
• Prunus avium confers root hypoxia sensitiveness to their genotypes and hybrids.
• Waterlogging strongly affected gas exchange parameters in sensitive genotypes.
• Morpho-anatomical adaptations are associated to root hypoxia tolerant genotypes.

Prunus species are considered as hypoxia-sensitive, although differences exist in the degree of tolerance among different genotypes. Our aim was to evaluate the responses and adaptations of different Prunus rootstocks species under root hypoxia. Prunus rootstocks, ‘Mariana 2624′ (Prunus cerasifera × Prunus munsoniana W. Wight & Hedrick), ‘Cab6P’ (Prunus cerasus L.), ‘Colt’ (Prunus avium (L.) L. × Prunus pseudocerasus Lindl.), ‘Maxma 14′ (Prunus mahaleb L. × Prunus avium), ‘Maxma 60′ (Prunus mahaleb × Prunus avium), ‘Garnem’ (G × N15) (Prunus dulcis (Mill.) Rchb. × (Prunus persica (L.) Batsch × Prunus davidiana (Carrière) N.E.Br.)) and ‘Mazzard F12/1′ (Prunus avium) were subjected to waterlogging for 14 days and physiological and morphological responses were assessed. Severe leaf damage, early plant mortality, decreases in photosynthesis rate (A) and stomatal conductance (gs) and higher concentration of malondialdehyde (MDA) were detected in sensitive genotypes when in waterlogged soil. However, in tolerant ones, gas exchange parameters and MDA concentration were unaffected in such condition. In addition, development of hypertrophied lenticels on the stem, adventitious roots and aerenchyma were observed in tolerant genotypes under waterlogged plants, being these morpho-anatomical adaptations reported here for the first time in these Prunus rootstocks. A comparative study of the most contrasting genotypes; i.e., ‘Mariana 2624′ (tolerant) and ‘Mazzard F12/1′ (sensitive), revealed that these morpho-anatomical changes would be playing a key role in survival of the tolerant Prunus genotype during O2 deprivation caused by waterlogging.