Induced androgenesis in tomato (Lycopersicon esculentum Mill.). III. Characterization of the regenerants.

We present data on the morphological, cytological, biochemical and genetic characteristics of tomato regenerants obtained through anther culture. As a result of induced androgenesis, more than 6,000 rooted regenerants were developed that differed both from the donor plants and among each other with respect to habitus and leaf, flower and inflorescence morphology. Cytological analysis revealed a great variability in chromosome number in the cells of the regenerated plants. While most of the regenerants were mixoploid, the majority of the cells had a haploid chromosome number. R(1) and R(2) progenies were tested for their resistance to Clavibacter michiganense subsp. michiganense ( Cmm 7). Some of the regenerants were resistant to the pathogen. A biochemical analysis of fruit from R(3) and R(4) plants showed a higher content of dry matter, sugars and vitamin C in the regenerant plants obtained from the hybrids than in those from the cultivars and control plants. The values of the parameters of hybrid regenerants grown in the greenhouse were about 1.5-fold higher than those of the hybrid regenerants grown in the field, and this trend is clearly expressed in all of the hybrid regenerants. The results obtained suggest that induced androgenesis and gametoclonal variation may be used as an additional tool to create a large range of new forms. The application of the latter in breeding programs would accelerate the development of tomato lines and varieties that would be more productive, disease-resistant, highly nutritive and flavour-acceptable.

Induced androgenesis in tomato (Lycopersicon esculentum Mill.) I. Influence of genotype on androgenetic ability : I. Influence of genotype on androgenetic ability.

The androgenetic ability of 85 Lycopersicon esculentum Mill. genotypes was tested. Callus was induced from anthers of 53 lines and hybrids. Regeneration of plants was obtained only from calli of 15 genotypes. The data obtained clearly showed that the genotype affects induced androgenesis in tomato. The in vitro response of anthers from the cultivars Roma, Pearson, San Marzano, Por, Sar, Vigapol, Day, David and Start, containing the ms 1035 gene, which is responsible for male sterility in tomato, confirm the strongly expressed dependence of both callus induction and organogenetic potential on the homozygous or heterozygous state of that gene. A protocol of callus induction, organogenesis and plant regeneration has been developed. More than 6000 regenerants have been obtained. Most of them showed different morphological alterations and variations in chromosome number (n, 2n, 4n). Some are interesting as source material for tomato breeding.

Induced androgenesis in tomato (Lycopersicon esculentum Mill). II. Factors affecting induction of androgenesis.

The influence on androgenesis of donor plant growth conditions, anther size and developmental stage of the microspore, medium composition and different anther treatments prior to culture was investigated in L. esculentum Mill. cv Roma and its hybrids. Growth conditions of donor plants affected the induction of tomato androgenesis. Anthers isolated from plants grown in the greenhouse during winter at high humidity and in short days possessed higher androgenetic ability than those grown in the field. The physiological state and age of the donor plants also influenced the processes investigated. Regarding the developmental stage of microspores, the period from prophase to telophase II is optimal for tomato anther implantation. More then 20 culture media were tested. Two, based on Murashige and Skoog medium were selected as most favourable for callus induction, organogenesis and regeneration. The effect on callus induction of 2ip in combination with indole-3-acetic acid (IAA) was greater than that of zeatin and IAA. Zeatin promoted entire plant regeneration. A highly significant interaction between genotype and medium was observed. Temperature and gamma ray treatments of anthers enhanced callus production, shoot formation and plant regeneration. Treatments at 4 °C (48 h) and 10 °C (9 days) stimulated these processes. Combined treatment of anthers with 4 Gy and 10 °C for 9 days was the most efficient.

Morphogenetic potential and in vitro micropropagation of endangered plant species Leucojum aestivum L. and Lilium rhodopaeum Delip.

The present work deals with the in vitro methods for rapid propagation, and morphogenetic potential of the rare and endangered bulb species Leucojum aestivum L., Amaryllidaceae, and Lilium rhodopaeum Delip., Liliaceae. The morphogenetic potential of different plant organs (bulb, stem, leaves and ovaries) was studied. Leaves of Leucojum aestivum L. and basal parts of the bulb in Lilium rhodopaeum Delip. possess the highest regeneration activity. Murashige and Skoog (MS) medium + 1 mg/l 6-benzylaminopurine (BAP) + 1 mg/l kinetin and Linsmaier and Skoog (LS) medium + 0.5 mg/l 1-naphthaleneacetic acid (NAA) + 0.1 mg/l kinetin were favourable for direct organogenisis from these explants. A stimulating effect of alow gamma-irradiation dose (5 Gy) upon the quantity and growth intensity of the bulbs formed by the explants in in vitro conditions is observed.