Ovule culture

ovule cultre is used to produuce whole plants

1. Ovule Culture Mrs. Praveen Garg VITS College, Satna

2. Ovule culture is an experimental system by which ovules are aseptically isolated from the  ovary. It is grown aseptically on chemically defined nutrient medium under controlled conditions . Ovaries and unfertilized ovules are also possible alternative sources for haploid or doubled-haploid production. Introduction

3. Structure of Ovule The ovule is a multicellular oval-shaped structure which originates from the placenta and lies inside the chamber of the ovary.  Each chamber may consist of one or more number of ovules.  A fully mature ovule consists of the stalk or  funicle  and the  body .  One end of the funicle is attached to the placenta and the other end to the body of the ovule.  The point of attachment of the funicle with the body is called  hilum .  Funicle sometimes extends up to the base of the ovule and the ridge thus formed is called  raphe . The body of the ovule shows two ends – the basal end often called, the  chalaza  and the upper end, known as the  micropylar  end. 

4. The main body of the ovule is covered with one or two envelops called the integument.  In some cases, however, there may be a single layer of integument.  Accordingly, the ovules are referred to as  unitegmic  or  bitegmic .  The integument gives protection to the internal tissues. There is a small opening at the apex of the integument called the  micropyle .  The integument encloses a large parenchymatous tissue known as  nucellus .  In center of the nucellus is situated the female gametophyte known as embryo-sac which develops from a functional megaspore.  The embryo sac bears the embryo and is the most important part of the ovule.

5. Principle An ovule is a mega sporangium covered by integument. Ovules are attached with placenta inside the ovary by means of its funiculus . An ovule contains a megaspore or an egg cell. After fertilization, a single cell zygote is formed which ultimately leads to form a mature embryo possessing shoot and root primordia . Ovules can be isolated and cultured in nutrient medium. In vitro ovule culture helps to understand the factors that regulate the development of a zygote through organized stages to a mature embryo. Alternatively , it may be possible to germinate pollen in the same culture as the excised ovule and to induce in vitro fertilization and sub­sequently embryo production.

6. Protocol Collect the open flower (unfertilized ovules). If fertilized ovules are desired, collect the open flower where the anthers are dehisced and pollination has taken place. To ensure the fertilization, collect the flower after 48 hrs. of anther dehiscence. Remove sepals, petals, androecium etc. from the ovaries containing either fertilized or unfertilized ovules. Soak the ovaries in 6% NaOCl (sodium hypochlorite) solution . Rinse the ovaries 3-4 times with sterile distilled water. Using sterile techniques, ovules are gently prodded with the help of spoon shaped spatula by breaking the funicles at its junction with placental tissue .

7. The spatula with ovules is gently lowered into the sterile solid or liquid medium as the culture vial is slanted about 45°. Damaged or undersized ovules are rejected when possible, during transfer. Incubate the ovule culture in either dark or light (16 hrs. 3,000 lux ) at 25°C.

8. Importance Of Ovule Culture Through ovule culture, test tube pollination and fertilization can be done. By technique, it may be possible to germinate pollen in the same culture as the excised ovule and to induce a vitro fertilization leading to the formation of mature seeds containing viable embryos . Ovule culture has been successfully employed to obtain hybrid seedlings in Interspecific and Intergeneric crosses . By ovule cultures, viable hybrids have been obtained in three out of five crosses. It is possible to obtain haploid callus by culturing unfertilized ovules.

9. Thank You