Anther culture-derived regenerants of durum wheat and their cytological characterization.

Abstract

Anther culture is being increasingly used in cereal crop improvement both as a source of haploids and for inducing new genetic variation. We studied the androgenetic ability and regenerability of 10 cultivars of durum wheat (Triticum turgidum L., 2n = 4x = 28; AABB), using three different growth conditions and four media. From a total of 86,400 anthers cultured, 324 plants were obtained: 248 green and 76 albino. Genotype, growth condition, and media significantly affected anther response and callus production; interactions were also significant. Green plant regeneration was influenced significantly by genotype and growth condition, as well as by genotype and growth condition interactions. Albino plant regeneration was significantly affected only by growth condition. Regenerants showed gametoclonal/somaclonal variation. Differences in morphology, growth habit, adult plant height, spike size, and development of spikes at nodes were observed. Mitotic and meiotic chromosomes were studied by conventional staining and fluorescent genomic in situ hybridization techniques. Chromosome numbers of the regenerants ranged from 14 to 70. All 76 haploid plantlets (2n = 2x = 14; AB) were albino. Some of the 28-chromosome regenerants were also albino. Chromosome number in the green plantlets ranged from 28 to 70. Chromosome number also varied in regenerants originating from the same callus. Both intergenomic and intragenomic multivalents were observed. An interesting feature was the preferential multiplication of B-genome chromosomes, which formed multivalents (trivalents, quadrivalents, and hexavalents). We observed several chromosomal abnormalities, which seemed to increase with the level of polyploidy. Translocations, dicentric chromosomes, chromatid exchanges, and Robertsonian translocations involving the A- and B-genome chromosomes were observed. Chromosome breakages resulting in centric and acentric fragments, and telocentrics were observed. Chromosome multiplication and structural aberrations induced during culture may constitute the bases of gametoclonal and somaclonal variations.