Plants Reproductive Adaptations

Front 1

The basic flower structure

Back 1

Inside the flower there is the filament which runs up from the receptacle which has the anther at the end. This is the stamen of the flower. In the middle is the Pistil.

In the pistil is the ovary and the stigma at the top.

Front 2

Pollen development

Back 2

The sporophytic tissue is the anther that contains 2n mother cells. These split by meiosis twice, producing a tetrad that is 1n. This is then released as a microspore. The tapetum is also present as the cell wall which protects the cells as well as providing a sticky substance that is used as an adhesive product.

Front 3

pollen tube

Back 3

The pollen tube grows down from the top to the ovary of the stigma. The pollen passes down through the tube to the ovary for fertilisation. The ovary will develop a tough lining which eventually develops into a fruit and the stigma and stamen shrivel away.

Front 4

Dicliny

Back 4

The flowers are either male or female.

Front 5

Monoecy

Back 5

Where male and female occur in the same plant.

Front 6

Dioecy

Back 6

A colony contains only either male or female individuals.

Front 7

temporal mechanism to stop self fertilisation: protoandry

Back 7

in hermaphrodites, the development of male organs before the appearance of the corresponding female products stop self fertilisation. Therefore, the anthers mature before the stigma.

Front 8

temporal mechanism to stop self fertilisation: sequential hermaphroditism (protogyny)

Back 8

They can change from a male to female, or vis versa. Or from female to hermaphrodite. (begins life as a female and then eventually becomes a male. Therefore, the stigma matures before the anther.

Front 9

Biochemical mechanism to stop self fertilisation in plants:

Back 9

Heteromorphic incompatibility/self incompatibility: Morphological differences - Either short anther and long style or the other way round.

Either a papillate stigma or a cob stigma.

Front 10

Homomorphic incompatibility

Back 10

The phenotype of the pollen is determined by its own gametophytic haploid genotype.

Front 11

sporophytic self incompatibility

Back 11

The phenotype of the pollen is determined by the diploid genotype of the anther.

Front 12

Gametophytic biochemical self incompatibility mechanisms:

Back 12

-S-alleles in just the pollen.

-The pollen segregates: each pollen grain carries only 1 allele gene product.

-Arrests pollen tube growth

-Homology to RNAses

Example: Nicotiana

Front 13

Sporophytic

Back 13

S-alleles expressed in the tapetum, proteins trapped in the pollen exine.

All pollen carries both the gene products

Arrest pollen germination

Receptor-like mechanism

Example: Brassica