Orchids aren’t easy, but that makes them fun

It happened four days before Valentine’s Day, in my grocer’s produce department. A new shipment had just been rolled out from the back room, triggering a full-blown swoon in some of Yakima’s more weather-wearied food shoppers. You’re thinking it was lush strawberries for dipping in chocolate? The first California asparagus? No, it was even more sublime.

Breathtakingly perfect Phalaenopsis orchids had been potted and beribboned for gifting our sweethearts. It’s been a long, long winter, and these pretties had us at “hello.”

The orchid family is so large (25,000 species) that it’s estimated that one in every 15 flowering plants in the world is an orchid. Found in nearly every environment (including above the Arctic Circle), the great majority are tropical. They can be epiphytic, meaning they grow on trees, or lithophytic, growing on rocks. Orchids that grow in soil are called terrestrial, and are usually found in the world’s temperate regions.

Not that long ago, orchids were for the wealthy, or the serious plant connoisseur. They were certainly not something you would grab, along with a bag of potatoes or onions, on a quick trip to the grocery store.

What kept them uncommon is the fact that orchids are notably difficult to propagate from seed. Unlike most seeds, dust-sized orchid seeds lack nutritional storage tissue, which made mass distribution from conventional propagation difficult. These days, new micropropagation techniques, often called tissue culture, and advances in stem cell technology, have made some orchids almost as the ubiquitous as ordinary houseplants, and just as affordable.

Bacterial contaminants of plant tissue culture

Bacterial contaminants of plant tissue culture from Amer T. Wazwaz

Aseptic Techniques in Plant Tissue Culture

Aseptic techniques in plant tissue culture from kumarkanika

Plant Tissue Culture Technique and its applications

Plant Tissue Culture Technique and its applications from Komal Jalan

The Many Dimensions of Plant Tissue Culture Research

The practice of plant tissue culture has changed the way some nurserymen approach plant propagation. In the recent past, the applicability of this technology to the propagation of trees and shrubs has been documented. Some firms have established tissue culture facilities and commercial scale operations are presently in operation for the mass propagation of apples, crabapples, rhododendrons, and a few other selected woody species. The intent of this research update is to briefly examine "what is being done" and to explore "what can be done" with regard to the tissue culture of ornamental plants. Such a consideration necessarily includes an overview of tissue culture as a propagation tool. The major impact of plant tissue culture will not be felt in the area of micropropagation, however, but in the area of controlled manipulations of plants at the cellular level in ways which have not been possible prior to the introduction of tissue culture techniques.

THE ART AND SCIENCE OF MICROPROPAGATION

Of all the terms which have been applied to

History of Plant Tissue Culture

The theoretical basis for plant tissue culture was proposed by Gottlieb Haberlandt in his address to the German Academy of Science in 1902 on his experiments on the culture of single cells (2). He opioned that, to my knowledge, no systematically organized attempts to culture isolated vegetative cells from higher plants have been made. Yet the results of such culture experiments should give some interesting insight to the properties and potentialities that the cell, as an elementary organism, possesses. Moreover, it would provide information about the interrelationships and complementary influences to which cells within a multi cellular whole organism are exposed (from the English translation, [3]). He experimented with isolated photosynthetic leaf cells and other functionally differentiated cells and was unsuccessful, but nevertheless he predicted that one could successfully cultivate artificial embryos from vegetative cells. He, thus, clearly established the concept of totipotency, and further indicated that the technique of cultivating isolated plant cells in nutrient solution permits the investigation of important problems from a new experimental approach. On the basis of that 1902 address and

Plant Tissue Culture: A Review

Plant tissue culture refers to growing and multiplication of cells, tissues and organs of plants on defined solid or liquid media under aseptic and controlled environment. The commercial technology is primarily based on micro propagation, in which rapid proliferation is achieved from tiny stem cuttings, axillary buds, and to a limited extent from somatic embryos, cell clumps in suspension cultures and bioreactors. The cultured cells and tissue can take several pathways. The pathways that lead to the production of true-to-type plants in large numbers are the preferred ones for commercial multiplication. The process of micro propagation is usually divided into several stages i.e., pre-propagation, initiation of explants, subculture of explants for proliferation, shooting and rooting, and hardening. These stages are universally applicable in large-scale multiplication of plants. The delivery of hardened small micro propagated plants to growers and market also requires extra care.

1. Preparation of nutrient medium:
A semi-solid medium is prepared in double distilled water containing macro elements, micro elements, amino acids, vitamins, iron source, carbon source like

Great Overview Video of the Tissue Culture Process

Tissue Culture Terminology

Plant tissue culture - a collection of techniques used to maintain or grow plant cells, tissues or organs under sterile conditions on a nutrient culture medium of known composition

Callus - Undifferentiated, swollen cell mass forming under the influence of elevated plant hormone levels.

Etiolation - Yellow and stretched plant; parts elongate until light is intercepted.

Explant - Part of an organism used in "in vitro" culture.

IAA - Indoleacetic acid; a plant hormone increasing cell elongation and, under certain circumstances, implicated in stimulating cell division and root formation. IAA moves in a polar manner in plants forming an IAA gradient in tissues. Orientation of plant organs, then, influence callus formation and morphogenesis.

"in vitro" - "In glass"; as in tissue culture methods

Morphogenesis - Change in shape

Polarity - Orientation in gravitational field.

Primordia - The earliest detectable stage of an organ, such as a leaf, root or root branch.

Root Hairs - Epidermal cell extensions of

What is Tissue Culture?

Tissue Culture is the process of replicating cells in a sterile environment. Typically this is done in glass containers. The plant cells are placed in or on a nutrient rich media: liquid, semi-liquid or solid (agar). Many times this process is called 'in vitro' culture.

• Agar is a jelly like substance with nutrients for the plant cells to pull from as they multiply.   

In the picture above you can see the plants are growing in agar, the translucent media at the base of the container.

There are several parts of the plant that can be considered a culture or starting point. This includes, shoots, nodes, roots, callus, single cells, seeds and embryo. Many factors go into whether or not the plant cells will replicate, including chemicals, viability of the plant parts, maintained sterile environment and the growing media. 

Check out this biology discussion to see more.