In vitro culture of wheat. III. Anther culture of the a genome aneuploids in common wheat

[In vitro androgenesis response of durum wheat disomic substitution]

The variety 'Langdon' and its substitution series were used to evaluate the effect of each substituted chromosome of the A and B genomes on the in vitro androgenetic potential. This study showed the implication of chromosomes 1B and 5B in repressing embryogenesis. Genes located on these chromosomes seem to have an inhibitor effect. The substitution of these chromosomes by their homeologous ones from the D genome increased the number of embryos while with the presence of the original genes the number of embryos was less than in the control. Chromosome 5B is also especially involved in the regeneration of green plants. The genetic control is inhibitory; this explains the difficulty of obtaining good levels of in vitro androgenesis in durum wheat. In this study no effect of the D genome on the androgenetic response of the substitution lines was observed.

Substitution analysis of callus induction and plant regeneration from anther culture in wheat (Triticum aestivum L.)

The genetic determination of callus induction, total plant regeneration and green plant regeneration from anther culture were studied using a "Chinese Spring"/"Cheyenne" substitution series. All the three characteristics were found to be polygenically determined, but their inheritance was independent from one another. The 7A and 18 chromosomes had a considerable effect on callus induction. In the case of total plant regeneration the most influential chromosome "as the 3A while the 2D chromosome showed a definite influence on green plant regeneration. The interaction between the genetic background of the recipient plant and the substituted chromosome plays an important role in the manifestation of the studied features.

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

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.

The effect of the 4B chromosomes of hexaploid wheat on the growth and regeneration of callus cultures

Calli were initiated from immature embryos of nine lines of hexaploid wheat (Triticum aestivum L. em. Thell). These were the euploid lines Chinese Spring and Cappelle-Desprez, a line of Chinese Spring ditelocentric for the long arm of 4B, four substitution lines of Chinese Spring in which chromosome 4B has been replaced by its homologues from different wheat varieties and substituted into Chinese Spring and a substitution line of Besostaya I 4B into Cappelle-Desprez. The calli from these lines were found to differ in their growth rates and morphogenic and regenerative activities. The substitution of different 4B chromosomes into Chinese Spring significantly increased morphogenesis and shoot regeneration from callus. The potential for developing wheat lines with improved culture characteristics is discussed.

The effect of specific chromosome and cytoplasm substitutions on the tissue culture response of wheat (Triticum aestivum) callus

Calli were initiated from immature embryos of four lines of hexaploid wheat (Triticum aestivum L. em. Thell), the euplasmic nuclear donor 'Chinese Spring', 'Chinese Spring' in which both 4B chromosomes were substituted by those of the variety 'Cappelle-Desprez' and two alloplasmic lines in which these nuclei were substituted into the cytoplasm of Aegilops ovata. The calli were found to differ in their initia growth rates and their ability to organise shoot primordia and regenerate shoots. The 'Cappelle' 4B chromosomes had a very significant effect on all these characters. The potential for modelling genotypes for improved tissue culture characteristics is discussed.

Cultivar and cultivar x environment effects on the development of callus and polyhaploid plants from anther cultures of wheat

Plants of three common wheat (Triticum aestivum L. em. Thell) cultivars and one randomly selected doubled-haploid line derived by anther culture from each of the three cultivars were each grown in three environments, a field environment, a greenhouse environment, and a growth chamber environment. Anthers containing largely miduninucleate to late uninucleate microspores were cultured and calli were induced to regenerate plants in order to assess the effects of cultivar, cultivar family (cultivar and corresponding doubled-haploid derivative), anther-donor plant environment, and cultivar X environment interaction on androgenic responses. Large differences in response were observed among cultivars as well as between cultivars and doubled-haploids. Differences between cultivar and doubled-haploid within cultivar family usually resulted from higher frequency of response in the cultivar, contrary to the hypothesis that anther culture per se constitutes a general selective device for superior androgenic responses. Also, in a second experiment, anther callusing frequency was greater in the cultivar 'Kitt' than in any of five unique doubled-haploid lines derived from 'Kitt'. Significant effects were also observed in the first experiment for the interactions of cultivar family X environment as well as doubled-haploid vs. cultivar X environment, although the effect of environment itself was less significant than these interactions.

Genetic variation in tissue cultures of red clover

Design II matings were made among randomly selected clones of 'Arlington' red clover (Trifolium pratense L.). Progeny were evaluated in vitro on two regeneration media for callus growth and differentiation. Additive genetic variance was a significant source of variability for nearly all traits evaluated, including somatic embryogenesis. In vitro traits, such as rapid callus growth, colony vascularization, root initiation, chlorophyll production and embryogenesis were highly heritable and should respond to breeding and selection. Dominance genetic variance was significant for only a few in vitro characters. Maternal and cytoplasmic factors were significant primarily in the early subcultures. Highly significant additive genetic correlation of performance on two regeneration media was found. A population selected on one of the regeneration media for such characteristics as improved plantlet regeneration, rapid callus growth, long term colony viability or the frequency of root initiation should show correlated improvement on the other medium. No significant differences for embryogenesis were attributable to differences in the regeneration media used. Furthermore, no interaction of additive genetic effects with regeneration media were observed. These data indicate that improvement in the frequency of plantlet regeneration from callus of red clover could effectively be achieved by breeding and selection for embryogenic types.

The influence of paternal species on the origin of callus in anther culture of Solanum hybrids

Stamen culture of several Solanum species and interspecific hybrids was performed and each stamen was scored for presence and origin of callus. Each species and hybrid has a characteristic callus growth pattern - either no growth (0), callus growth from the filament (F), or callus growth from the anther (A). Characteristic growth types of the interspecific hybrids indicate that callus growth takes precedence over no growth. Hybrids between F and A species exhibit mainly paternal passage of either characteristic callus type. Possible explanations for this pattern of inheritance are male plastome factors or imprinting of paternal genes. The latter explanation is presently preferred.