Production of Triticale, Polyploidy breeding

Production of Triticale, Polyploidy breeding

• In Every organism, chromosomes are found in constant numbers.

• The number of chromosomes that make the basic set in an organism, known as haploid condition. If  any organism has two sets of chromosomes, such an organism is called diploid.

• Some organisms have more than two sets of chromosomes and both sets are unusual; this condition is called polyploidy. Winkle introduced the term polyploidy.

Read more about the Mutation breeding

• There are several conditions of polyploidy in organism.If one egg is fertilised by more than one sperm or due to failure of Mitosis or meiosis during gamete formation.

• Interestingly, polyploidy conditions are also induced by artificially Colchicine induced polyploidy because it does not allow the separation of chromosomes because it arrests the process of formation of spindles

Types of polyploidy

• Polyploidy is of two types - Autopolyploidy and Allopolyploidy.

• When a plant with lower chromosome number has suddenly increased chromosome number  than normal value, it is called Autopolyploidy. 

• For Example- a diploid organism has AA chromosome whereas An autotriploid and autotetraploid  organism has AAA and AAAA chromosome number.

Read more about the Hybridisation: Method of crop improvement

• An autotriploid organism is usually sterile because there is a problem in pairing during meiosis but they are used in Horticulture.

• When autotriploid  plants are vegetatively propagated they produce seedless fruits due to sterile conditions in Banana and Watermelon.

• In some plants autotriploid conditions increase the size of fruit. For example - Many apples and pears have large fruit content .

• Autotriploid apples and pears are produced by crossing between diploid and tetraploid. When the number of chromosomes are increased after crossing in organisms called allopolyploids.

• This condition is produced by the hybridization between two closely related species having chromosome set AA and BB.The hybrid is produced with chromosome set AB and is sterile.

• If the new AB genetic combination undergoes an induced personal doubling then a fertile AABB tetraploid is produced.

Read more about the Selection: Method of crop improvement

• Polyploidy breeding is used by the plant breeders for improving the yield of wheat , rice, sugarcane  flax, cotton and they are natural polypoids. Polyploid breeding is an important source of variations and helps in evolution.

• Allopolyploids are frequently used by the plant breeders to get fertile hybrids from different species and from different genera.

• Triticale has been developed by crossing between Triticum and Secale (Rye) by botanist A.S. Wilson in 1873.