Inducing Homoeologous Chromosome Pairing In Interspecific Hybridization In Wheat Using The Phi Gene

Limitation or lack of chromosome pairing and recombination between related chromosomes is one of the main constrains in wide hybridization programs in wheat. Consequently, useful genes can not be transferred from wild relatives to the cultivated species. The present study was conducted to investigate the effectiveness of the PhI gene transferred from Aegilops speltoides into bread wheat cultivar Chinese Spring (CS), in inducing homoeologous chromosome pairing in interspecific crosses using the Chinese Spring line, CS(PhI), carrying the gene. Chinese Spring as well as CS(PhI) were crossed as female parents with three accessions of Ae. kotschyi (UUSS), one accession of Secale cereale(RR), two amphiploids of Triticum durum-Ae. Caudate (AABBCC), and one amphiploid of Triticum durum-Ae. umbellulata (AABBUU). Meiotic metaphase I chromosome pairing was studied in all the interspecific crosses with CS as well as CS(PhI). The level of pairing was compared in the two sets of crosses using t-student statistical test. Level of chromosome pairing in the two crosses of CS and CS(PhI),was compared with chi-square test, where the level of pairing in the former being as the expected and in the later as the observed values. There was a significant increase in chiasma frequency in all the crosses with CS(PhI) over those with CS. Significant reduction in the frequency of univalents and increase in bivalents, multivalent and chiasma frequency in crosses of amphipods with CS(PhI) as compared to those of CS indicated induced homoeologous pairing. The results of this study unequivocally demonstrated the effectiveness of the PhI gene transferred from Ae. speltoides to hexaploid wheat in inducing homoeologous chromosome pairing. It also suggested that the line CS(PhI) can effectively be used for precise transfer of useful alien genetic variations with minimum linkage drag.