Apomixis and Polyembryony — Definition

Definition

Imagine a plant that can produce seeds, and from those seeds, new plants grow, just like normal. But here's the twist: these seeds are formed without the usual 'mating' process – no pollen fertilizing an egg cell.

This fascinating phenomenon is called Apomixis. It's like a plant having a shortcut to reproduction, creating offspring that are exact genetic copies of itself, bypassing the genetic mixing that happens in sexual reproduction.

Think of it as asexual reproduction that cleverly disguises itself as sexual reproduction because it still produces seeds. This is incredibly useful for plants, especially if they live in environments where pollinators are scarce or if they want to pass on a particularly good set of genes without any changes.

Now, let's talk about Polyembryony. This term literally means 'many embryos.' Normally, one seed contains one embryo, which develops into one plant. But in polyembryony, a single seed contains two, three, or even more embryos!

It's like finding multiple babies in one cradle. These extra embryos can arise in several ways: sometimes the original embryo splits into several, or other cells within the ovule (like the nucellus or integuments, or even synergids and antipodals) decide to develop into embryos alongside the 'main' one.

A classic example where you might encounter this is in citrus fruits like oranges or lemons; if you plant a seed, you might sometimes see multiple seedlings emerge from it. This phenomenon is also very important because it can lead to the production of genetically identical seedlings (especially if the extra embryos come from nucellar cells), which is highly desirable in horticulture for maintaining specific plant varieties.

So, while apomixis is about *how* seeds are formed (without fertilization), polyembryony is about *how many* embryos are found *within* a seed.