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Parade of Polyploids

The Parade of Polyploids is a yearly feature in the genetics course of Jim Birchler at the University of Missouri, Columbia. Professor Birchler uses real plants for the parade. We have recreated the parade in silico. Ed Himelblau has been taking pictures of polyploids and paleopolyploids. Additional pictures have been gleaned from open sources and are credited as applicable. We have divided the two categories below.

Polyploids

Potato

Potato flowers. Potato is an autotetraploid. Image courtesy of Keith Weller at the USDA photo library.

Strawberry

The cultivated strawberry is an octaploid hybrid derived from hybridization of two natural octaploids.

Banana

This supermarket banana is most likely the common variety Cavendish, an autotriploid of Musa acuminata.

Xenopus laevis

Polyploids are found among animals. The African clawed frog is an allotetraploid. Related species, such as Xenopus tropicalis, are diploid. Photo courtesy of Xenbase.

Viscacha rat

Polyploids are not unusual among fishes and amphibians, but until recently had not been observed among higher vertebrates. Several reports indicate that the red viscacha rat is a tetraploid (Tympanoctomys barrerae). A polyploid mammal is unexpected because the XY sex-determination system is very dosage sensitive.

Rainbow trout

Polyploid trouts occur naturally and can be induced from diploid by heat shocking fertilized eggs. Diploid x tetraploid crosses produce sterile triploids that are often used in restocking stream and lakes. Image courtesy of Stephen Ausmus, USDA-ARS Photo Library

Soybean

Seeds of soybean. Soybean is a paleotetraploid. It is thought that two acient parental genomes joined to form a allotetraploid, which subsequenty diploidized. Image courtesy of Steve Hurst @ USDA-NRCS PLANTS Database.

Oat

Seeds of Oat (Avena sativa). Oat is a allohexaploid, like bread wheat. Image courtesy of Jose Hernandez @ USDA-NRCS PLANTS Database

Wheat

Seeds of bread wheat. Wheat is a allohexaploid. Its genome consists of three ancestral parental genomes. Image courtesy of Steve Hurst @ USDA-NRCS PLANTS Database.


Peanut

Seeds of peanut on a freshly uprooted plant. Peanut is an allotetraploid. Image courtesy of David Nance USDA photo library.

Coffee

Maturing fruits of arabica coffee (Coffea arabica). Arabica coffee is an allotetraploid. Its genome consists of two ancestral parental genomes. Image courtesy of Mark Skinner @ USDA-NRCS PLANTS Database.

Coffee

Mature seeds of arabica coffee. Arabica beans make coffee of better aroma and quality than beans from the related Coffea robusta species. Image courtesy of Steve Hurst @ USDA-NRCS PLANTS Database.

Cotton

Mature seeds of cotton are released in a "ball" from opening capsules. Cotton is an allotetraploid. Image courtesy of David Nance, USDA-ARS photo library.

Brassica

Brassica rapa (left) and Brassica oleracea (right) are diploids. Brassica napus (center) is an allopolyploid formed by hybridization of the B. rapa and B. oleracea genomes. Essentially, Brassica napus has both the B. rapa and B. oleracea genomes together in a single nucleus. While Brassica napus has formed spontaneously in nature, the napus line shown here was generated recently by polyploidy researchers. Allopolyploids often show heterosis (hybrid vigor) relative to their diploid parents and the plants shown here illustrate this.

Paleopolyploids

Bok-choy

Bok-choy is actually Brassica rapa, a diploid. It is featured here because of two reasons: It is a paleopolyploid: a polyploid that has diploidized by losing duplicated genes over evolutionary time. Brassica rapa is the ancestral parent of the allopolyploid Brassica napus, the cultivated rapeseed. The other ancestral parent is Brassica olereacea (see below).

Cauliflower and Broccoli

Cauliflower and broccoli are variations of Brassica oleracea, a diploid. It is featured here because of two reasons: First, Brassica oleracea is the other ancestral parent of the allopolyploid Brassica napus, the cultivated rapeseed. Second. Brassica oleracea is a paleopolyploid: a polyploid that has diploidized by losing duplicated genes over evolutionary time. It is thought that the redundancy in the Brassica oleracea genome facilitated the breeding of many morphologically-distinct variaitons (see additional images bellow).

Brussels sprouts

Brussels sprouts are yet another variation of Brassica oleracea.

Kohlrabi

Kohlrabi is another variation of Brassica oleracea.

Cabbage

Purple and Green cabbages are other variations of Brassica oleracea.

Kale

Kale is yet another variation of Brassica oleracea.

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