Chromosome Manipulations for Crop Improvement

Abstract

The parallelism established between Mendel’s laws of inheritance and chromosomal theory of inheritance during 1900-1904 laid the foundation of cytogenetics. Later, a series of cytogenetic stocks such as monosomics, trisomics, haploids, autotetraploids, synthetic and extracted aloploids, alien chromosome addition and substitution lines were developed in several crops Advances were also made in molecular cytogenetic techniques such as chromosome banding, chromosome image analyzing systems, genomic in situ hybridization (GISH), fluorescence in situ hybridization (FISH) including fiber-FISH, micro-dissection of chromosomes, flow sorting of chromosomes, and, more recently, in developing artificial plant chromosomes. Cytogenetic stocks have been characterized genetically and cytologically and are being ‘used in construction of molecular, genetic, physical and comparative maps. Several breeding lines have been developed and varieties released through haploidy breeding. Autotetraploids have been produced in numerous crops. A large number of interspecific hybrids and amphiploids have been produced. Alloploid breeding involving crosses between natural diploid/polyploids × synthetic alloploids and manipulation of alien addition and substitution lines have met with great success. Several useful genes have been transferred utilizing cytogenetical tools for resistance to diseases, insects, abiotic stresses, CMS sources and quality traits in wheat, oats, cotton, rice, Brassica and other horticultural species. Genes for cyst nematode and BYDV resistance have been introgressed through tissue culture induced chromosomal exchanges. FISH has been employed in numerous studies to characterize alien segments. Integration of chromosome manipulation techniques and molecular cytogenetic techniques with structural and functional genomics is essential to solve some of the plant breeding problems.