Effect of Iron Source and Medium pH on Growth and Development of Sorbus commixta In Vitro

Abstract

Sorbus commixta is a valuable hardwood plant with a high economical value for its medicinal and ornamental qualities. The aim of this work was to investigate the effects of the iron (Fe) source and medium pH on the growth and development of S. commixta in vitro. The Fe sources used, including non-chelated iron sulfate (FeSO4), iron ethylenediaminetetraacetic acid (Fe-EDTA), and iron diethylenetriaminepentaacetic acid (Fe-DTPA), were supplemented to the Multipurpose medium with a final Fe concentration of 2.78 mg·L−1. The medium without any supplementary Fe was used as the control. The pH of the agar-solidified medium was adjusted to either 4.70, 5.70, or 6.70. The experiment was conducted in a culture room for six weeks with 25 °C day and night temperatures, and a 16-h photoperiod with a light intensity of 50 mmol·m−2·s−1 photosynthetic photon flux density (PPFD). Both the Fe source and pH affected the growth and development of the micropropagated plants in vitro. The leaves were greener in the pH 4.70 and 5.70 treatments. The tissue Fe content decreased with the increase of the medium pH. The leaf chlorophyll content was similar between plants treated with FeSO4 and those with Fe-EDTA. The numbers of the shoots and roots of plantlets treated with FeSO4 were 2.5 and 2 times greater than those of the control, respectively. The fresh and dry weights of the shoot and the root were the greatest for plants treated with Fe-EDTA combined with pH 5.70. The calcium, magnesium, and manganese contents in the plantlets increased in the pH 5.70 treatments regardless of the Fe source. Supplementary Fe decreased the activity of ferric chelate reductase. Overall, although the plantlets absorbed more Fe at pH 4.70, Fe-EDTA combined with pH 5.70 was found to be the best for the growth and development of S. commixta in vitro.

A Critical Review of Methodologies for Evaluating Iron Fertilizers Based on Iron Reduction and Uptake by Strategy I Plants

“…Fuentes et al [ 43 ] reported a reduction in FCR root activity levels in chlorotic cucumber plants treated by foliar Fe application. Similarly, Xiao et al [ 53 ] obtained higher FCR rates in Fe-deficient plants than in plants growing in a medium with Fe treatments. On the other hand, there are other experiments where FCR activity in chlorotic plants without Fe supplementation showed lower FCR activity ratios than in plants with treatments to alleviate chlorosis.…”

“…The common thread across all studies is that FCR is activated in the roots by the presence of an Fe source in the rhizosphere as a mechanism for its subsequent uptake while the methodology applied may differ. Some studies were conducted in vivo by removing plants from the growing media and submerging roots in an aerated solution with the corresponding sequestering ligand [ 17 , 24 , 25 , 26 , 27 , 28 , 40 , 44 , 49 , 52 , 53 ]. Other studies use excised root segments from the plants, called in vitro , and similarly these root samples are immersed in solutions [ 16 , 18 , 29 , 39 , 41 , 42 , 43 , 45 , 46 , 47 , 48 , 50 , 51 , 54 , 55 , 56 , 57 ].…”

Iron Source and Medium pH Affect Nutrient Uptake and Pigment Content in Petunia hybrida ‘Madness Red’ Cultured In Vitro

“…The composition was (in mg·L −1 ): Ca(NO 3 ) 2 ·4H 2 O 436.6, KNO 3 232.3, KH 2 PO 4 272.0, MgSO 4 ·7H 2 O 209.1, NH 4 NO 3 80.0, K 2 SO 4 17.4, H 3 BO 3 1.40, CuSO 4 ·5H 2 O 0.20, MnSO 4 ·4H 2 O 2.10, Na 2 MoO 4 ·2H 2 O 0.12, and ZnSO 4 ·7H 2 O 0.80, containing 3.0% ( w / v ) sucrose and 0.80% ( w / v ) agar. The iron sulfate (FeSO 4 ·7H 2 O) or iron chelated with ethylenediaminetetraacetic acid (Fe-EDTA) were used as the Fe sources, according to the protocol of Xiao et al [ 42 ] with a final Fe content of 27.8 mg·L −1 in the MNS medium, and the treatment without Fe was used as the control. Before autoclaving, the pH of the medium was adjusted to 4.70, 5.70, or 6.70 with 1 M NaOH or HCl.…”

“…Moreover, petunia is also very sensitive to the surrounding NH 4 + and NO 3 − [ 40 , 41 ]. In some previous studies, the effects of the Fe source and pH on the growth of shrub ornamental plants Sorbus commixta [ 42 ] and Hydrangea macrophylla [ 43 ], as well as the regulation of Fe-handling gene expressions, were studied. Moreover, in previous studies, more attention was paid to the effects of the NH 4 + and NO 3 − supply on the Fe absorption of plants, while studies seldom discussed the effects of different Fe sources and pH on plant ammonium and nitrate contents.…”

Iron Supplement-Enhanced Growth and Development of Hydrangea macrophylla In Vitro under Normal and High pH

“…It is necessary to investigate the responses to different Fe sources and pH levels. In our previous studies, supplemental FeSO 4 or Fe-EDTA have been found to have a growthpromoting effect on sensitive plants Sorbus commixta [31]. However, the regulation mode of Fe is not discussed in depth.…”