Submitted to: In Vitro Cellular and Developmental Biology - Plants
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 23, 2013
Publication Date: October 3, 2013
Citation: Reed, B.M., Wada, S., De Noma, J.S., Niedz, R.P. 2013. Mineral nutrition influences physiological responses of pear in vitro. In Vitro Cellular and Developmental Biology - Plants. 49:699-709. Interpretive Summary: Micropropagated (tissue culture) plants sometimes develop growth disorders and their causes are not well understood. During our study of mineral nutrition to improve growth of pear shoot cultures we also noted the effect of minerals in the medium on these disorders. Mineral nutrients were tested over a range of concentrations using a computer designed experiment. Shoot cultures of five types of pears were grown on each treatment combination and analyzed to determine the factors that contributed to growth disorders and also the factors that remedied them. Many of the factors affecting overall shoot quality also contributed to specific physiological disorders. Most of the disorders could be alleviated with the proper concentrations of mineral nutrients.
Technical Abstract: Physiological disorders such as callus, shoot tip necrosis and hyperhydricity are some of the most difficult challenges in micropropagation and their causes are not well understood. A comprehensive medium optimization study to improve the growth of pear shoot cultures was also designed to determine the effects of mineral stock solutions on physiological disorders. Five Murashige and Skoog mineral salt factors were tested over a range of concentrations in a 5-dimensional surface response experimental design. Pyrus communis ‘Old Home × Farmingdale 87,’ ‘Horner 51’ and ‘Winter Nelis,’ P. dimorphophylla and P. ussuriensis ‘Hang Pa Li’ shoot cultures were grown on 43 computer designed treatments. Analysis of shoot response to these treatments identified the factors that contributed to physiological disorders and also the factors that remedied them. Callus was common for pear shoots cultured on the standard medium and decreased on formulations with increased NH4NO3, Fe and mesos (CaCl2, KH2PO4 and MgSO4) for most genotypes. Shoot-tip necrosis varied with the genotype but low mesos or low nitrogen concentrations contributed to the necrosis. Hyperhydricity was more prominent with low mesos or low NH4NO3. Hooked and upward curled new leaves were seen in most genotypes and were due to low mesos in P. communis cvs., nitrogen and mesos for ‘Hang Pa Li,’ and micro nutrients and mesos for P. dimorphophylla. Fasciation and hypertrophy were seen infrequently. For most genotypes, Murashige and Skoog medium with moderate NH4NO3 and higher mesos produced normal shoots without physiological disorders.