Aneuploid and alloplasmic lines as tools for the study of nuclear and cytoplasmic control of culture ability and regeneration of scutellar calli from common wheat

Abstract

Twenty four B genome aneuploid lines (di-telosomics, nullisomic-tetrasomics and tetrasomics) of Triticum aestivum cv 'Chinese Spring' were used in an analysis of the culture ability and regeneration capability of scutellar calli. Several correlations were found between the presence or absence of specific chromosomes and chromosomal arms of the B genome of common wheat and the growth and differentiation capabilities of these calli. The rate of callus growth decreased only when the long arm of chromosome 6B was not present. The absence of chromosomes 3B and 7B did not result in an apparent change in morphogenetic capability, while the absence of other B genome chromosomes was significantly correlated to changes in the frequency of calli that regenerated plants. The presence of the short arm of chromosome 1B was negatively correlated with regeneration, whereas its long arm is probably required to counteract this effect and to maintain the normal ratio of regeneration. The presence of the chromosomal arm 2BS seemed to be essential for differentiation to shoots. In the absence of the short arms of chromosomes 4B and 5B, the rate of regeneration was slightly reduced. In the absence of the long arm of chromosome 6B there was a marked reduction of the ability of scutellar calli to regenerate plants. The use of additional aneuploid lines belonging to homoeologous group 6 revealed that only calli derived from lines having chromosome 6D in their complement regenerated plants similarly to the euploid control. Culture ability and regeneration capability were also analysed with alloplasmic lines of T. aestivum cv 'Chris'. The lines were derived from five species, representing plasma-types of different phylogenetic distances from plasma-type B of T. aestivum. The results showed that when the endogenous cytoplasm (B-type) was exchanged with T. timopheevii cytoplasm (G-type) there was a significant increase in the regeneration of shoots from the scutellar calli.