Abstract
Shoot-tip cultures of Pyrus elaeagrifolia Pallas, an important gene source for drought and chlorosis resistance in pear rootstock breeding, were established from a wild mature tree originated from seed. Murashige and Skoog basal medium supplemented with different concentrations of benzyladenine (BA) singly or in combination with auxin was used in the study. In the initial culture, the highest percentages (>80%) of shoot proliferation were obtained in the mediums supplemented with 9.0 μM BA and 0.5 μM indole-3-acetic acid. In the subcultures, the highest shoot proliferation rates were obtained in the medium containing 4.5 and 9.0 μM BA. The shoot proliferation rates ranged from 91.1 ± 2.4 to 96.4 ± 2.0% in the second subculture and from 76.7 ± 7.8 to 89.4 ± 3.3% in the third subculture. In the second subculture, the shoots grown on 9.0 μM BA without auxin produced the best proliferation (10.6 ± 1.6). For the in vitro rooting experiments, the highest rooting rate (54.2 ± 10.4%), root length (10.5 ± 2.4 mm), and root number (2.5 ± 0.6) were obtained from 10 days dark treatment on the medium containing half strength of macronutrients supplemented with 5 μM indole-3-butyric acid (IBA). For the ex vitro rooting experiments, shoot rooting was significantly influenced by 10 mM IBA applied as quick-dip method. The percentage of rooting was 55 ± 9.6% and root number was 1.8 ± 0.3 at this concentration.
Highlights
Iron-chlorosis in pears is a widespread problem, in regions with calcareous soils (Dolcet-Sanjuan et al, 2004)
Plant Material In the present study, a wild mature tree originated from the seed of P. elaeagrifolia Pallas was used as plant material, and in vitro shoot-tip cultures were established from actively growing shoots
The highest percentages (>80%) of shoot proliferation were obtained from the medium supplemented with 9.0 μM BA and 0.5 μM indole-3-acetic acid (IAA) (Table 1) In the second and the third subcultures, the shoot multiplication rate was significantly influenced by BA concentrations with the highest obtained from 4.5 to 9.0 μM BA concentrations
Summary
Iron-chlorosis in pears is a widespread problem, in regions with calcareous soils (Dolcet-Sanjuan et al, 2004). Pyrus elaeagrifolia Pallas is one of the gene sources used to improve rootstock tolerance to drought and chlorosis (Lombard and Westwood, 1987). According to Lombard and Westwood (1987), drought tolerance and nitrogen, phosphorus, iron, boron, and zinc uptake from soil of pear scion cultivar by P. elaeagrifolia are at high levels. This species is resistant to black end, pear decline, and wooly pear aphid. Healthy pear trees could be grown in arid soils with pH 7.5–8 Seedlings of this species display high genetic variation. Vegetative clonal propagation techniques could be used for selected P. elaeagrifolia genotypes as rootstocks
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