An Optimized Micropropagation Protocol by Ex Vitro Rooting of Pear Rootstock OHF 333 (Pyrus communis L.)

Abstract

Pear rootstock OHF 333 ( Pyrus communis L.), which is included in the US ‘Old Home’ × ‘Farmingdale’ series, is characterized by good compatibility with most other varieties, high yields, and a moderate degree of resistance to fire blight. Micropropagation in vitro has shown promise for rapid, large-scale cloning of disease-free plant material throughout the year. However, pear shoots are often recalcitrant to rooting, and this process is highly genotype-dependent. This study aimed to improve the micropropagation protocol by ex vitro rooting of pear rootstock OHF 333 ( Pyrus communis L. ‘Old Home’ × ‘Farmingdale’). Charkor, a new plant growth regulator of natural origin was used, which contains metabolism products of symbiotic fungus-endophytes of ginseng roots, as an alternative to synthetically produced plant growth regulators (PGRs). Microcuttings were obtained from in vitro cultured shoots and subjected to four different treatments for ex vitro rooting: 1 g L −1 1-naphthaleneacetic acid (NAA) (as a powder), 0.5 mL L −1 Charkor for 3 hr or 6 hr, or the same concentration of Charkor prepared as a powder. Microshoots dipped in sterile distilled water with no additional hormonal treatments served as controls. Cultures were kept in a growth chamber under a 16-hr photoperiod, with air humidity maintained close to 100% (above 96%) for 2 weeks and then gradually reduced to 60%. Data on final acclimatization rate (survival rate; %), mean number of roots per plant, stem and root length, mean number of leaves per plant, and final acclimatization rate were collected 90 days after transplanting to ex vitro conditions. All treatments induced a successful acclimatization rate of more than 31%. The highest survival rate (86%) and longest stems were achieved by treatment with 0.5 mL L −1 Charkor for 6 hr. The greatest mean number of roots per plant, root length, and number of leaves was achieved in the variant treated with 1 g L −1 powdered NAA.

Selection for Sustainable Preservation through In Vitro Propagation of Mature Pyrus spinosa Genotypes Rich in Total Phenolics and Antioxidants

“…Other researchers have also reported successful acclimatization with various survival rates in a number of Pyrus species, such as 50% up to 83-90% for P. communis [45] and [8] or [43], respectively, 73% for P. pyrifolia [46] and 95% for P. syrica [32]. In a more recent study, Dimitrova et al [47] reported, for P. communis, a faster and better in vitro rooting and acclimatization protocol by using a commercial plant biostimulator of natural origin named Charkor.…”

Self-pruning in lime (<i>Citrus aurantifolia</i> Swingle) after treatments with ichiphon, abscisic acid and nitrogen, phosphorus, and potassium fertilizers

“…In olives, leaf abscission was accelerated by ABA or ethylene treatment, and the combination of ABA and ethylene treatments showed an effective additive effect in leaf abscission. Abscisic acid can accelerate abscission directly (Estornell et al, 2013;Taylor & Whitelaw, 2001), while some studies suggest that ABA promoting organ abscission depends on interactions with ethylene and auxin (Roberts et al, 2002;Wilmowicz et al, 2016;Dimitrova & Nacheva, 2021). Moreover, ABA can promote abscission through ethylene (Gómez-Cadenas et al, 2000).…”

Regenerative potential and its variability in different topophysical zones of Kalanchoe daigremontiana leaves in in vitro culture conditions

“…In such cases, the only effective method of propagation is micropropagation. Since experimenters most often want to regenerate whole plants in in vitro cultures, they are more interested in shoot organogenesis (caulogenesis) than root organogenesis (rhizogenesis) [Dimitrova andNacheva 2021, Kuang et al 2021].…”