Nodular competent callus was induced on the basal cut surface of the shoot apex explants cultured on MS (Murashige and Skoog) medium supplemented 1, 3, or 5 mg/L thidiazuron (TDZ) and incubated in darkness for one week followed by 4 weeks under white fluorescent light. A high percentage of proliferated callus was obtained with the medium containing 1 mg/L TDZ. The separated callus pieces were maintained on the same fresh medium. Shoot differentiation, following each of three successive maintenance passages, occurred on the medium either lacking or containing 1 mg/L benzyladenine (BA). The shoots developed roots on medium with 1 mg/L IBA. Up to seventy-five percent of the produced plantlets were acclimatized to the ex vitro conditions. The novel protocol may be useful for biotechnological applications in salvia improvement via genetic transformation or mutagenesis and cloning approaches.

Shoot-tip explants were excised from axenic and non-axenic plant cultures of two cumin (Cuminum cyminum L.) landrace lines from Assiut (ASS) and Qina (QIN), Egypt. Explants were cultured on MS (Murashige and Skoog, 1962) medium supplemented with different concentrations of benzyladenine (BA) or kinetin. The two landraces performed similarly throughout the study. Shoot-tip explants from axenic cultures were superior to those prepared from non-axenically grown plants regarding the percentage of explants that produced micro-shoots and the number of micro-shoots that proliferated. The maximum number of excisable micro-shoots was produced on medium with 1 μM BA. Up to 20 micro-shoots per explant were excised from cultures on this medium. The largest number of micro-shoots obtained on medium containing kinetin was five. Most (80-90%) micro-shoots formed roots on medium with 1 μM indole-3-butyric acid (IBA) and 2% (w/v) polyethylene glycol (PEG-6000). The survival rate ex vitro was as high as 70%. A high concentration of BA (4 μM) induced calli, retarded elongation of the micro-shoots and reduced both the number of roots formed on subsequent rooting medium, and plant survival ex vitro. This study supports the feasibility of in vitro cloning of cumin using shoot tips for germplasm collection, conservation and exchange.

Shoot-tip explants were excised from axenic and non-axenic plant cultures of two cumin (Cuminum cyminum L.) landrace lines from Assiut (ASS) and Qina (QIN), Egypt. Explants were cultured on MS (Murashige and Skoog, 1962) medium supplemented with different concentrations of benzyladenine (BA) or kinetin. The two landraces performed similarly throughout the study. Shoot-tip explants from axenic cultures were superior to those prepared from non-axenically grown plants regarding the percentage of explants that produced micro-shoots and the number of micro-shoots that proliferated. The maximum number of excisable micro-shoots was produced on medium with 1 μM BA. Up to 20 micro-shoots per explant were excised from cultures on this medium. The largest number of micro-shoots obtained on medium containing kinetin was five. Most (80-90%) micro-shoots formed roots on medium with 1 μM indole-3-butyric acid (IBA) and 2% (w/v) polyethylene glycol (PEG-6000). The survival rate ex vitro was as high as 70%. A high concentration of BA (4 μM) induced calli, retarded elongation of the micro-shoots and reduced both the number of roots formed on subsequent rooting medium, and plant survival ex vitro. This study supports the feasibility of in vitro cloning of cumin using shoot tips for germplasm collection, conservation and exchange.

Growth and osmotic potential of calli induced from leaf- and root-derived tissues of six tepary bean lines (Phaseolus acutifolius) varying in drought resistance were assessed in vitro after polyethylene glycol-induced (10%, PEG-10,000) dehydration. Calli of resistant teparies were characterized by low initial osmotic potential (ψs) and relative growth rate (RGR) on medium lacking PEG (−0.30 MPa). However, calli of both resistant and sensitive lines were similar in dry matter percent (DM). Presence of PEG in the medium (−0.58 MPa) elevated DM in all teparies except one resistant line. Both leaf- and root-derived calli of sensitive teparies exhibited osmotic adjustment (OA) but reduced RGR that remained after rehydration in one line. We concluded that preexisting force of low cellular ψs rather than induced OA plays an important role in buffering adverse effects of dehydration and conditioning drought resistance of tepary beans. This information may aid Phaseolus breeders in screening for drought resistance among large number of accessions.

Growth and osmotic potential of calli induced from leaf- and root-derived tissues of six tepary bean lines (Phaseolus acutifolius) varying in drought resistance were assessed in vitro after polyethylene glycol-induced (10%, PEG-10,000) dehydration. Calli of resistant teparies were characterized by low initial osmotic potential (ψs) and relative growth rate (RGR) on medium lacking PEG (−0.30 MPa). However, calli of both resistant and sensitive lines were similar in dry matter percent (DM). Presence of PEG in the medium (−0.58 MPa) elevated DM in all teparies except one resistant line. Both leaf- and root-derived calli of sensitive teparies exhibited osmotic adjustment (OA) but reduced RGR that remained after rehydration in one line. We concluded that preexisting force of low cellular ψs rather than induced OA plays an important role in buffering adverse effects of dehydration and conditioning drought resistance of tepary beans. This information may aid Phaseolus breeders in screening for drought resistance among large number of accessions.

Nodular meristematic callus was induced on the basal cut surface of apical shoot explants of salvia cultured on Murashige and Skoog (MS) medium supplemented with 4.5, 13.5, or 22.5 μM thidiazuron (TDZ). Cultures were incubated in the dark for 1 wk and then transferred to light conditions for 4 wk. A higher percentage of explants developing callus was observed on medium containing either 4.5 or 13.5 μM TDZ, although explants on 4.5 μM developed larger calluses. The callus was maintained on medium containing 4.5 μM TDZ and 0.45 mM ascorbic acid. Shoot differentiation, after each of three successive maintenance passages, was induced from callus grown on medium containing either 4.4 or 8.8 μM benzyladenine (BA). A greater number of shoots were harvested from callus differentiated on BA (4.4 or 8.8 μM) medium with 0.45 mM ascorbic acid added. Shoots developed roots on MS medium supplemented with 4.9 μM of indole-3-butyric acid. The addition of ascorbic acid to the shoot differentiation medium enhanced rooting, number of roots per shoot, and survival rate. Approximately 75% in vitro plantlets were acclimatized to ex vitro conditions. Histological investigations confirmed both adventitious meristem initiation during the callus induction phase, and subsequent organogenic shoot development on the differentiation medium. The novel protocol for the meristematic callus induction and plant regeneration in this study may be useful for biotechnological applications for salvia improvement via genetic transformation or mutagenesis and in vitro propagation approaches.

Nodular meristematic callus was induced on the basal cut surface of apical shoot explants of salvia cultured on Murashige and Skoog (MS) medium supplemented with 4.5, 13.5, or 22.5 μM thidiazuron (TDZ). Cultures were incubated in the dark for 1 wk and then transferred to light conditions for 4 wk. A higher percentage of explants developing callus was observed on medium containing either 4.5 or 13.5 μM TDZ, although explants on 4.5 μM developed larger calluses. The callus was maintained on medium containing 4.5 μM TDZ and 0.45 mM ascorbic acid. Shoot differentiation, after each of three successive maintenance passages, was induced from callus grown on medium containing either 4.4 or 8.8 μM benzyladenine (BA). A greater number of shoots were harvested from callus differentiated on BA (4.4 or 8.8 μM) medium with 0.45 mM ascorbic acid added. Shoots developed roots on MS medium supplemented with 4.9 μM of indole-3-butyric acid. The addition of ascorbic acid to the shoot differentiation medium enhanced rooting, number of roots per shoot, and survival rate. Approximately 75% in vitro plantlets were acclimatized to ex vitro conditions. Histological investigations confirmed both adventitious meristem initiation during the callus induction phase, and subsequent organogenic shoot development on the differentiation medium. The novel protocol for the meristematic callus induction and plant regeneration in this study may be useful for biotechnological applications for salvia improvement via genetic transformation or mutagenesis and in vitro propagation approaches.

Initial and adjusted osmotic potentials of separate leaf- and root-derived calli were assessed in vitro for two teparies (Phaseolus acutifolius A. Czray) and a common bean (P. vulgaris L.) cultivar differing in physiological and morpho-physiological reactions of intact plants to water stress. Unstressed leaf- and root-derived calli of common bean (CB) had higher preexisting osmotic potential (ψs) and relative growth rate (RGR) but lower dry-matter percent (DM) than those of tepary bean (TB) lines when grown on basal Murashige and Skoog medium (-0.30 MPa). Exposure to water stress (-0.58 MPa) imposed by adding polyethylene glycol (10% [w/v], PEG-10,000) did not affect these parameters for leaf-derived callus of CB and both leaf- and root-derived calli of TB. However, root-derived callus of CB showed decreased ψs that was maintained after transferring stressed callus onto medium lacking PEG for recovery from water stress. Nevertheless, its RGR decreased and DM increased. Stressed plants of both CB and TB grown in the greenhouse manifested significant reduction in leaf, stem, and root dry mass and leaf area. However, the magnitude of mass reduction was especially high for CB stem, leaf, and root. While TB root system penetrated deeper in the soil profile, CB root depth did not significantly change in response to drought. In addition, substantial CB root mass was detected in the top 10 to 20 cm of the soil profile. Stomata conductance and transpiration rate were higher for CB than TB under both well-watered and water-stress conditions. Significant relative water content reduction was detected only in CB. In spite of water stress, soil moisture was high around roots of CB compared with TB, suggesting lesser efficiency of CB root system to extract water. Stressed CB grown in the production field did not produce seed yield whereas TB gave 60 to 64% of its potential dry seed yield. In vitro assay for root osmotic potential should be useful in improving drought resistance in common bean.