Ovary culture is the in-vitro technique which is carried outside on a suitable nutrient medium in an unpollinated flower to grow new haploid plants. The process of ovary culture refers as “Gynogenesis” as the ovary is the female reproductive part or also refers to as “Gynoecium”.
Gynogenesis was first studied by the scientist San Noem in 1976. For the Gynogenesis, we can select either pollinated or un-pollinated flower. A pollinated flower is cultured into the simple nutrient medium whereas the un-pollinated flower is cultured on the special medium added with synthetic auxins and sucrose.
Content: Ovary culture
Definition of Ovary culture
Ovary culture can define as the in-vitro culturing of ovaries in an aseptic condition from the pollinated or un-pollinated flowers, in an appropriate nutrient medium and under optimal conditions.
Ovary culture gives rise to haploid plantlets by the fertilization of egg-cell or megaspore either through embryogenesis or regeneration from callus.
What is Ovary
Ovary: An ovary is a part of a flower which is the female reproductive part and also refers as “Gynoecium”. The ovary is the part of carpel which also includes long style, terminal stigma and ovule within the ovary.
Style and Stigma: The ovary is present below the style or pistil which resembles the long, slender tube on the terminal of which stigma is present.
Ovule: Within the ovary, there is an ovule which also refers to as “Megasporangium” as it carries megaspore or egg-cell. The integument surrounds the egg-cell. The egg cell undergoes fertilization by which a zygote is produced that later develops into a mature embryo.
The principle of gynogenesis is based on the Regeneration principle, where an ovary can regenerate into a fully differentiated plant. In the ovary culture, the flowers are excised from the plant either in pollinated or non-pollinated stage, and from that pistil containing ovary is removed. The ovary comprises of ovule which is a female reproductive part of a plant by the growth on nutrient medium and under controlled conditions.
Gynogenesis includes the following steps:
- First, collect the open flowers from a healthy plant, in a sterilized zip-lock bag.
- Wash the flowers with the distilled water.
- Then, dip the flowers into the 5% of Teepol solution for 10 minutes.
- Again, wash with the flowers with the distilled water.
- Wash the flowers again with the distilled water.
- Bring the flowers to the laminar airflow chamber.
- Then subject the flowers for surface-sterilization by immersing in a 5% of sodium hypochlorite solution for 5-7minutes. And, then wash it with the distilled water.
- To a sterile Petri-plate, transfer the surface sterilized flower and by using sharp scalpel dissect out the calyx, petal, anther filaments etc. to separate the ovary.
- Then, the ovary can culture either through induction or regeneration process. In induction, the ovaries float over the liquid medium. And, in regeneration culture the ovaries on the solid nutrient medium.
- Incubate the cultures for 16hours at 25֯ C. For the regeneration of ovary, keep the culture plates in a daylight regime by using a fluorescent lamp. Place the culture tubes in a dark for the induction process.
- After 2 weeks, haploid plantlets grow either through embryogenesis or through plant regeneration from callus.
Ovary culture helps in the study of the early stages of embryo development. Gynogenesis also helps in the study of fruit development and its physiology including maturation.
From the culture of the un-pollinated pistil, the effect of phytohormones on the parthenocarpic fruit can be studied. Role of floral organs can be studied which plays a significant role in fruit development.
Gynogenesis also helps in inducing Polyembryony where instead of single plantlet, many shoots also develop. Ovary culture also explains the in-vitro pollination and seed formation method.
The culture of an ovary from the apomictic plant can help us to understand the stimulus provided by pollination. As in apomistic plant, there is no fertilization, the only pollination occurs which alone stimulates the ovary growth and seed development.
Ovary culture also helps to understand the hybridization process to obtain hybrid varieties of seedlings by crossing over of interspecific and intergenic species.
The frequency of haploid production is very low in Ovary culture as only 1-5% of the responding ovaries are there. This technique requires high technical skills and management. In some case, besides a haploid plant, some different traits may develop. Gynogenesis can be employed only in limited species, for example, wheat, rice, maize, sugar beet etc.