Nucellar embryony

Figure 1. Nucellar Embryony Process

Nucellar embryony is a form of asexual reproduction in plants, particularly in certain species of flowering plants. This phenomenon occurs when an embryo is formed from the nucellus tissue of the ovule, rather than from the fertilized egg cell. As a result, the offspring are genetically identical to the parent plant.

Mechanism

In nucellar embryony, the nucellus cells, which are diploid and part of the maternal tissue, give rise to an embryo. This process bypasses the normal sexual reproduction mechanism involving the fusion of gametes. The nucellar cells undergo mitotic divisions to form an embryo, which eventually develops into a seedling. This type of reproduction ensures the propagation of the parent plant's genetic traits without variation.

Occurrence

Nucellar embryony is commonly observed in certain species of the Rutaceae family, particularly in citrus plants such as oranges, lemons, and grapefruits. It is also found in some species of the Sapotaceae family, such as mango.

Advantages

One of the primary advantages of nucellar embryony is the production of uniform and true-to-type plants. This is particularly beneficial in agriculture and horticulture where consistency in crop quality and characteristics is desired. Additionally, nucellar embryony can help in the preservation of desirable traits in cultivars.

Disadvantages

Despite its advantages, nucellar embryony can also have drawbacks. The lack of genetic diversity in the offspring can make the plants more susceptible to diseases and pests. Furthermore, the absence of genetic variation limits the potential for evolution and adaptation to changing environmental conditions.

Applications

Nucellar embryony is utilized in the propagation of certain fruit crops to maintain the quality and uniformity of the produce. It is also used in plant breeding programs to preserve and propagate elite genotypes.

See also

• Apomixis
• Polyembryony
• Somatic embryogenesis
• Vegetative reproduction