Cytogenetics of Triticale: Chromosomal Anomalies And Intergeneric Chromosome Combination

Abstract

Three triticale lines and two Triticum species were used for the present study. The triticale lines are triticale BAT-1 (2n=56), triticale BAT-2 (2n=56), and triticale WRF (2n=42) and two Triticum species are Triticum aestivum (2n=42) and Triticum durum (2n=28). Objective of this study was to determine the chromosome combination in triticale derives from the respective parents Secale cereale and Triticum species in addition to find out the influence of meiotic anomalies in semisterility of triticale lines. In present study, that has been determined following some important cytological events. Interphase nuclear phenotype of triticale lines and Triticum species were studied. Nuclear volume (NV) and Interphase nuclear volume (ICV) were found to be statistically different and higher than that of Triticum species which are their one of the parents. The homogeneity of the distribution of chromosomal morphology in three cells of triticale BAT-1, triticale BAT-2, triticale WRF, Triticum aestivum and Triticum durum were tested by the use of contingency table in corporating chromosome length and arm ratio classes. Total haploid complement lengths and chromosome distribution of triticale and Triticum species were determined. Highest CV% was 2.18 in triticale BAT-1 and the lowest value was 0.612 in Triticum aestivum. Other CV% values were 0.96 (triticale BAT-2) 1.94 (triticale WRF) and 1.36 (Triticum durum). 2-values were also determined, where highest value was 10.081 in triticale BAT-1 and lowest value was 0.044 in triticale BAT-2. Other 2 values were 0.13 (triticale WRF), 16.60 (Triticum aestivum) and 0.095 (Triticum durum). Chromosome association and chaisma frequency in different genotypes in the present investigation were found to vary. Frequency of normal bivalent was very low and that of univalent was very high in all triticale lines. Trivalent and quadrivalent were also found in triticale. Triticum durum was found to show mainly quadrivalent. Triticum aestivum normally exhibited bivalent. The different meiotic irregularities were found mostly in triticale lines. Laggard, fragment, bridges and unequal distribution of chromosome were found frequently in all triticale lines but rarely in Triticum species. Pollen grain abnormality and pollen sterility were also observed in all triticale lines. In triticale lines pollen sterility were found to vary from be 30.25% (triticale BAT-1) to 37.80% (triticale BAT-2). The highest percentage for pollen gram in abnormality was 40.00 (triticale BAT-2) and lowest was 37.25 (triticale BAT-1). Several crosses were made among triticale lines and Triticum species reciprocally, but the results were found to be very poor. The F1s of the crosses were not found to survive. However, from crossing program and karotypic study it may be said that triticale lines are semisterile. The chromosomes of Secale cereale and Triticum species are present in triticale, but they cannot combine during meiosis and thus normal gametes are not formed.