Ovary Culture: Meaning, Principle, Protocol and Importance | Plant Tissue Culture

In this article, we will discuss about the meaning, principle, protocol and importance of the ovary culture.

What is the Meaning of Ovary Culture?

Ovary culture is a technique of culture of ovaries isolated either from pollinated or un-pollinated flowers.

Principle:

Ovary is a ovule bearing region of a pis­til. Excised ovaries can be cultured in vitro. For many species e.g. tomato, gherkin (Cucumis anguria) excised ovaries grow in culture and form the fruits that ripen and produce viable seeds. This development takes place on a simple nu­trient medium containing only mineral salts and sucrose, provided the flowers have been fertil­ized two or more days before excision (Fig 2.4).

But the ovaries of un-pollinated flowers do not grow on simple nutrient medium. However, use of some synthetic auxins such as 2, 4-D, 2 4 5- T (2, 4-5-trichlorophenoxyacetic acid), NOA (2, Napthoxyacetic acid) in the nutrient medium in­duces the development of ovaries of un-pollinated flowers.

Often, in culture, the ovaries fail to grow into full size fruits in the restricted space of cul­ture vial. To overcome this problem, a partial sterile culture technique is devised in which only the long flower stalk is inserted into the aseptic nutrient medium through an opening in the stop­per, thus leaving the ovary free to grow outside the culture vial.

Protocol:

(1) Collect the pollinated or un-pollinated flow­ers from a healthy plant.

(2) Wash them thoroughly with tap water, dip into 5% Teepol solution for 10 minutes and again wash to remove the trace of Teepol.

(3) Transfer the flowers to laminar air flow cabi­net. Surface sterilizes the flowers by immers­ing in 5% sodium hypochlorite solution for 5-7 minutes. Wash them with sterile dis­tilled water.

(4) Transfer the flowers to a sterile petri dish. Using a flamed force and a surgical scalpel, dissect out the calyx, petals, anther fila­ments etc. of the flower to isolate the pis­til. During isolation of pistils care should be taken to ensure that the ovaries are not injured in any way. Damaged pistil, should be discarded as they often form callus tissue from the damaged parts.

(5) Place the ovaries on agar solidified nutrient medium.

(6) Incubate the cultures at 25°C in a 16 hrs, daylight regime at about 2000 lux. The light is provided by fluorescent lamp.

Importance:

Ovary culture is an useful technique to in­vestigate many fundamental and applied aspects.

Importance’s of Ovary Culture are:

(1) It is useful to study the early development of embryo development, fruit development, different aspects of fruit physiology includ­ing respiration, maturation and disease.

(2) The effect of phytohormones on parthenocarpic fruit development can be studied from the culture of un-pollinated pistil.

(3) Floral organs play a significant role in fruit development. Role of floral organs can be studied from the in vitro culture of ovary. In some cases it has been found that pollinated ovary produce the normal fruits in vitro if the sepals are not removed before culture.

However, if the sepals are removed before culture, addition of sucrose (5%) is neces­sary to obtain satisfactory growth of ovary in culture. In barley, lemma and palea are very important. In onion, the growth of ovaries without perianth is markedly inhibi­tory.

(4) In hybridization, the plant breeders face many problems such as the failure of pollen germination on the stigma or the slow and insufficient growth of pollen tube as well as precocious abscission of flowers. Ovary or pistil culture, in vitro fertilization (test tube pollination) has been used to circum­vent these obstacles. In many cases, suc­cessful results of in vitro fertilization and seed formation has been obtained.

Petunia Violaceae is a self-incompatible species. But in vitro pollination and seed formation over­come the self-incompatibility. Actually, in vitro fertilization has got the immense value in plant breeding where problems of incom­patibility or sterility exist as a barrier to normal sexual reproduction.

It might be possible, therefore, to produce a hybrid be­tween two species or varieties in vitro that could not be produced under normal in vivo conditions. Ovary culture has been success­fully employed to obtain hybrids of diploid Brassica chinensis and autotetraploid B. pekinensis which are normally cross incom­patible.

(5) Ovary culture has also been successful in inducing polyembryony. Poly-embryo may develop in culture from the various parts of the ovary. These poly-embryos give rise to many shoots instead of a single plantlet.

(6) The process of double fertilization not only brings about the formation of embryo and endosperm, but also stimulates the develop­ment of ovary into fruit. In most apomictic plants, although there is no fertilization, pollination alone stimulates the growth of the ovary and seed. The culture of ovaries of apomicts may, therefore, help in under­standing the nature of stimulus provided by pollination.