Tissue proliferation condition in micropropagated ericaceous plants

Abstract

Tissue proliferation (TP) is an abnormal tumorlike growth produced at or near the crown of the plant, but may also be found on aerial plant parts of some genotypes. Basal tumors may or may not be accompanied by proliferation of compact shoots with short internodes and a whorled leaf arrangement. Genera exhibiting TP include Rhododendron, Kalmia and Pieris of the Ericaceae family. Development of TP symptoms in a plant is highly correlated to a history of micropropagation and also to genetic background of the genotype. Similarities of TP symptoms to crown gall caused by Agrobacterium tumefaciens led many to initially believe TP to be a form of crown gall, but all evidence suggests that a pathogen is not involved in the TP disorder. Abnormal lignotuber formation is another possible cause for TP for which little supportive evidence could be developed. An epigenetic condition, possibly cytokinin habituation, is the possible cause of TP that is best supported by the majority of research evidence. It is likely that TP is induced in vitro by adventitious shoot formation, resulting from high cytokinin concentrations used to rapidly proliferate shoots. Some nursery production practices may result in increased TP symptoms development post-propagation. TP is well managed now due to greater awareness and adoption of sound micropropagation practices for ericaceous plants by tissue culture labs.

Impact of girdling and leaf removal on Alhagi sparsifolia leaf senescence

“…When plants exposed to adversity stress (e.g. osmotic pressure and temperature stress), the content of Pro and MDA tend to increase dramatically Brand 2011). Drought, high salinity, and high temperature often Predawn water potential, midday water potential, Pro content, MDA content, and ABA content of A. sparsifolia under control, phloem girdling, leaf removal, and combine girdling and removal after 1 and 30 days.…”