Are pollination and fertilisation necessary in apomixis? Give reasons.

NCERT Exemplar · Q35

Q. Are pollination and fertilisation necessary in apomixis? Give reasons.

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Concept understanding — Parthenocarpy Induction Mechanism

Let’s start with something you already know: a fruit is the ripened ovary of a flower. Normally, for that ovary to swell into a fruit, the flower must first be pollinated — pollen lands on the stigma, a pollen tube grows down, and fertilisation happens. Seeds then develop inside the fruit. That’s the usual sequence.

Now imagine a fruit that forms without any of that. No pollination, no fertilisation, no seeds. That’s parthenocarpy — from Greek parthenos (virgin) and karpos (fruit). The fruit develops from the ovary all by itself, as if it skipped the entire reproductive step.

How is that induced? In nature, some plants do it spontaneously — bananas, grapes, oranges, cucumbers. But commercially, farmers and horticulturists often induce parthenocarpy artificially. The mechanism is simple in principle: you trick the ovary into thinking it has been pollinated and fertilised.

The key is a group of plant hormones called auxins and gibberellins. When pollen lands on a stigma, it triggers a surge of these hormones in the ovary, which makes it grow. If you spray the flower with synthetic auxins (like 2,4-D or NAA) or gibberellins (like GA₃) at the right time, the ovary gets the same chemical signal — and starts swelling into a fruit, even though no fertilisation occurred.

Note

This is not genetic modification. It’s a hormonal treatment applied externally. The plant itself is not altered permanently; only that particular flower’s development is redirected.

Why does this matter? Two big reasons:

Seedless fruits — consumers prefer seedless watermelons, grapes, cucumbers. Parthenocarpy gives you that without any seeds to remove.
Reliable yield — if weather or lack of pollinators prevents pollination, the crop can still set fruit. This is especially useful in greenhouses or during rainy seasons when bees are inactive.

What NCERT says: In the Class 12 Biology textbook (Chapter 2, Sexual Reproduction in Flowering Plants), parthenocarpy is defined as the development of fruit without fertilisation. The textbook mentions that it can be induced by applying growth hormones like auxins, and that such fruits are seedless. Examples given: banana, grapes, cucumber. …

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Apomixis is a form of asexual reproduction through seeds, so pollination and fertilisation are generally not necessary — though in some cases, pollination may still be required to trigger seed development without actual fertilisation.

To understand why apomixis bypasses the need for pollination and fertilisation, we first need to recall what these processes normally achieve. In a typical flowering plant, pollination brings the male gamete (pollen) to the female gamete (egg), and fertilisation fuses them to form a zygote. That zygote then develops into an embryo inside the seed. Apomixis, however, is a clever evolutionary shortcut: the plant produces seeds without the fusion of gametes. The embryo develops directly from the mother plant's own cells — either from the egg cell without fertilisation (a process called parthenogenesis) or from some other cell of the ovule, such as a nucellar cell.

Because no male gamete is involved in forming the embryo, pollination is not required to deliver a sperm cell. And since there is no fusion of male and female nuclei, fertilisation does not occur. The seed that results is genetically identical to the mother plant — a clone, in effect. This is why apomixis is considered a form of asexual reproduction, even though it produces seeds.

Note

There is a subtle exception: in some apomictic plants, pollination is still needed to stimulate the development of the endosperm (the nutritive tissue in the seed). This is called pseudogamy. Here, pollen lands on the stigma and the pollen tube grows, but the sperm cell does not fuse with the egg. Instead, it may fuse with the polar nuclei to form the endosperm, while the embryo develops parthenogenetically. So pollination may be necessary for seed formation, but fertilisation of the egg is not. …

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Q.Are pollination and fertilisation necessary in apomixis? Give reasons.

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