Tagging of the specific genome and chromosome s of hexaploid wheat triggering chromosome elimination in wheat x Imperata cylindrica system of doubled haploidy breeding

Abstract

The present research endeavour entitled as tagging of the specific genome and chromosome(s) of newlinehexaploid wheat triggering chromosome elimination in wheat x Imperata cylindrica system of doubled newlinehaploidy breeding was undertaken at Molecular Cytogenetics and Tissue Culture Lab and Experimental newlineFarm of the Department of Crop Improvement, CSK HP Agricultural University, Palampur, Himachal newlinePradesh, India during 2010- 11 and 2011- 12 with the objective of identifying the wheat genomes and newlinechromosomes responsible for elimination of whole I. cylindrica chromosome complement in wheat x I. newlinecylindrica hybrids during early embryogenesis. Upon hybridization of different species of wheat viz., newlineTriticum monococcum, T. tauschii and T. durum with I. cylindrica, haploid embryos were recovered in T. newlinetauschii and T. durum only which revealed that the D and B genomes of hexaploid wheat are triggering the newlinepaternal chromosome elimination process. The possibility of enhancing the efficiency of embryo formation newlinevia increasing the exogenous supply of 2,4-D was also exploited and 0.03 % and 0.04 % of 2,4-D newlineconcentration were found optimum for haploid induction in T. durum and T. tauschii, respectively. The newlineinduction of haploid embryos in these species was also confirmed by cross-sectional studies of fertilized newlineovules derived after their hybridization with I. cylindrica. For further resolution of the genetic control of newlinepaternal chromosome elimination in wheat x I. cylindrica crosses, cytogenetic stocks viz., complete set of newlinemonosomic and nullisomic lines derived from Chinese Spring cultivar of hexaploid wheat and D genome newlinesubstitution lines of tetraploid wheat cultivar Langdon were crossed with I. cylindrica. Statistical analysis newlineof embryo formation frequency in monosomics revealed the role of 4D, 1D, 6B and 6D chromosomes as newlinethe absence of these chromosomes resulted in reduction of haploid embryo formation frequency from newlinecontrol as well as mean. These results were also supported by data obtained from nullisomics and newlinesubstitution line