Anti-inbreeding trick found in poppy genome

Scientists have identified an elusive male gene in the field poppy that stops self-fertilization, a mechanism that prevents inbreeding, and promotes greater genetic diversity.

Poppy flowers can recognise self-pollen with a neat genomic trick

Plant biologists had already uncovered that poppies prevent self-fertilization when a female gene on the stigma tells it which pollen to accept or reject, triggering several chemical signals to stop pollen tube growth. However, the corresponding “label” on pollen that allows recognition of “self” remained elusive. 
Professor Noni Franklin-Tong of the University of Birmingham School of Biosciences, said: “Finding this pollen component is a major breakthrough for us. Flowers recognise self and non-self pollen through a genomic region known as the S locus, which comprises a male and a female gene (in the pollen and pistil); these interact to allow ‘self recognition’. We already had the female S component identified, and now we have found the other half to this ‘lock and key’ - the elusive male pollen component, in this important cell-cell recognition and rejection system.

“This is a major achievement for us as it unlocks the mystery as to how poppy specifies recognition of ‘self’ pollen.”

Most flowering plants run the risk of pollinating themselves, rather than receiving pollen from another plant via an insect. The basic anatomy of many plants means pollen sacs are situated next to the female reproductive parts. Accidental self-fertilization is a real risk. When a flowering plant is pollinated, the pollen germinates and develops a pollen tube which grows through the stigma and female tissues and then enters the plant’s ovary to effect fertilization. If this involves self pollen, it results in inbreeding, which can result in a shrinking gene pool and unhealthy offspring.

Genetic diversity in plant science is vitally important for the breeding of new varieties of crops. By using generic traits, preserved over generations by mechanisms such as this, plant breeders are able to develop new varieties to help meet demands for more yield, with less input, on less land and in the face of a changing climate. Without such approaches, the world will not be able to meet the challenge of the growing food security crisis.