Philip J. Dale

Embryoids from Cultured Immature Embryos of Lolium multiflorum

Summary Cultured immature embryos of Lolium multiflorum gave various types of proliferation. Proliferating scutellum was observed to form embryo-like structures (embryoids) on its surface. Embryoids were picked off individually and regenerated into plantlets. Half the regenerated plantlets were albino but the green ones appreared morphologically normal. Scutellum proliferation was observed on a range of MS based media but 2 mg/1 2,4-D and 0.2 mg/1 BAP appeared most suitable for subsequent work. There is evidence that the frequency of embryos with scutellar proliferation varies with embryo size and plant genotype.

Pollen dimorphism and anther culture in barley

SummaryA dimorphism is observed in barley (Hordeum vulgare L., cv. Akka) pollen when stained with acetocarmine from the mid-binucleate stage onwards. The majority of grains have staining cytoplasms, while the remainder have cytoplasms which take up little or no stain (NS grains). The staining dimorphism cannot be detected at the late-uninucleate microspore stage when anthers are normally cultured, but the evidence suggests that the microspores have already diverged at this time and it is the cells destined to become NS grains in vivo that respond in culture to become pollen calluses. Evidence comes from a comparison of the frequencies of NS grains and pollen calluses and from their distribution between and within anthers.

Reproducible Regeneration of Callus from Suspension Culture Protoplasts of the Grass Lolium multiflorum

Summary Protoplasts have been isolated from suspension cultures that originated from single immature embryos of Italian ryegrass ( Lolium multiflorum ). Conditions required for efficient division and colony formation by these protoplasts have been investigated. Up to 50 % of the protoplasts developed walls and divided at low auxin (0.25 mg · 1 -1 NAA; 2,4-D; IAA) and low cytokinin (0.25 mg · 1 -1 , BAP) levels, but higher auxin levels were required for sustained cell division and colony formation. Culture of callus lines derived from protoplasts has not yet led to the regeneration of plants, although plants could be regenerated from one of the original suspension culture lines. The results are discussed with reference to the culture of other gramineous protoplasts.

Shoot tip culture in forage legumes

Abstract Shoot tips of Trifolium repens, T. pratense and Medicago sativa were cultured on various culture media. Blaydes basal medium and Gamborg B5 basal medium, both supplemented with 0.2 mg/l IAA and 0.2 mg/l 2iPA, gave good plantlet regeneration for T. repens (63–82%) and T. pratense (53–76%). Gamborg B5 with 0.2 mg/l NAA was best for M. sativa (80%). Almost 500 plantles were transferred to soil and no morphological abnormalities were observed. Preliminary studies on the cold storage of forage legume plantlets in vitro are promising.

Immature Inflorescence Culture in Lolium, Festuca, Phleum and Dactylis

Summary Immature inflorescences 1–20 mm long were cultured from forage grass species and hybrids in the genera Lolium, Festuca, Dactylis and Phleum. Many small plantlets were regenerated from all the grasses, either directly from floret primordia or via callus, and later transferred to soil. A good general culture medium contained MS basal constituents with 2 mg · l-1 2, 4-D, 0.2 mg · l-1 BAP and 100 mg · l-1 casein hydrolysate with the exception of Phleum pratense which gave rather more plantlets on MS with 0.5 mg · l-1 2,4-D without BAP and casein hydrolysate. The frequency of inflorescences with one or more albino shoots ranged from zero (Festuca arundinacea) to over 20% (Festuca pratensis). There was no evidence of genetic instability and the method may be useful for clonal propagation or for establishing aseptic plantlets for storage in vitro or experimentation.

Meristem tip culture in Lolium, Festuca, Phleum and Dactylis

Abstract Plants have been regenerated from meristem tips of grass species in the genera Lolium, Festuca, Phleum and Dactylis . Of the five culture media used the best general medium for the species investigated contained 0.01 mg/l 2,4-D and 0.2 mg/l kinetin and gave a plant regeneration rate of 8–92%. Variation in the survival of tips between species was highly correlated with the size of tips cultured, the longer the tip the higher the survival rate. 96% of the regenerated plants were later established in soil.

An investigation of morphogenesis within the genus Trifolium

Morphogenic responses within the genus Trifolium were investigated by culturing various explants from seedlings of 72 species. Seedlings from 32 species produced callus alone, 40 produced adventitious shoots and/or roots, of which 25 species produced only shoots and 7 species formed only roots. Seedlings within each species also varied in their response to culture. The section of these seedlings most likely to produce adventitious shoots was the original shoot with the remnants of the surrounding hypocotyl and cotyledons, followed by the excised cotyledons themselves.Inter- and intra-varietal variation was observed in T. repens. Genotypes that produced adventitious buds were selected and crossed. An improvement in the proportion of the population capable of morphogenesis was observed in one cultivar.

Condensed tannins in Trifolium species and their significance for taxonomy and plant breeding

SummaryPopulations of 59 Trifolium taxa were screened for condensed tannin content using the vanillin-HC1 test. Eight species (T. arvense, T. aureum, T. badium, T. campestre, T. dubium, T. micranthum, T. patens and T. spadiceum) were shown to contain tannins. These species are all found in Section Chronosemium or Section Trifolium Subsection Arvensia of the genus, and thus presence of tannins appears to have a taxonomic significance. Screening populations within species showed differences in tannin content, but no plants in these species were free of tannins.