Influence of biotechnological parameters on the yield of macrostructures from unfertilized seed germs of diploid sugar beet

Purpose. To determine the influence of biotechnological parameters on the yield of macrostructures from unfertilized seed germs of diploid sugar beet. Methods. Biotechnological, laboratory, analytical, statistical. Results. It was found that the use of 35% sodium hypochlorite solution at an exposure of 40 min allows to obtain from 73.13 to 75.83% of sterile seed germs. Exposure of 50 min allows to obtain the sterility of the source material from 83.58 to 85.39%. Sterilization of explants for 60 min allows to obtain sterility of the source material from 86.88 to 92.80%. The share of infected seed germs with increasing exposure decreased from 20.09–22.14 to 6.52–12.61%. The yield of macrostructures has been experimentally confirmed to significantly depend on breeding genotype and type of medium. The largest number of calluses (10–80%) was formed with the use of the Hamburg and Eveleg’s medium. With the use of he Murasige and Skoog’s medium, their share was 10–35%. Noteworthy, in breeding genotypes 07–181, 80% of genotypes formed buds and 35% formed calluses in the Hamburg and Eveleg’s medium. Of breeding genotypes 07–178, 55% of genotypes formed a callus and 80% buds. Conclusions. As a result of the conducted researches the influence of biotechnological parameters (exposure to 35% solution of sodium hypochlorite, type of nutrient medium) on the yield of macrostructures from unfertilized seed germs of diploid sugar beet was determined. It is optimal to carry out treatment with 35% sodium hypochlorite solution for 50–60 minutes, regardless of the selection number of sugar beet. To obtain macrostructures from unfertilized seed germs of diploid sugar beet, it is necessary to use the Hamburg and Eveleg’s medium for breeding genotypes 07–188, 07–178 and 07–181.

In vitro seed germination and seedling performance of Hibiscus coddii subsp. barnardii

Hibiscus coddii subsp. barnardii is an endemic South African plant species with ornamental potential. The limited plant availability in nature and restrictions on the collection of living plant material (cuttings) for cultivation purposes, necessitated the development of a protocol for in vitro seed propagation to ensure all year round ex vitro establishment of plants. The effect of culture medium on seed germination and seedling performance was therefore studied. Various types of sterile seed cultures, namely moist filter paper bridges, five different strengths (¼, ½, –, full, 1¼) of PGR-free Murashige and Skoog medium (MS) and solid Gelrite® medium (control) were investigated. High germination percentages (85%-98%) were found in all three seed cultures, although seeds germinated on filter paper, Gelrite ® and lower strengths (¼, ½, –) of MS medium had shorter mean germination times (1.6-2.8 days) than those germinated on full and 1¼ strengths (3.5-4 days) of MS medium. Furthermore, the growth performance of seedlings varied with the strength of MS medium and was best supported on full strength MS medium, whereas ¼ and ½ strength MS media and Gelrite® cultures were detrimental for seedling growth.

Understanding the cone scale in Cupressaceae: insights from seed-cone teratology in Glyptostrobus pensilis

Both wild-type and teratological seed cones are described in the monoecious conifer Glyptostrobus pensilis and compared with those of other Cupressaceae sensu lato and other conifers. Some Cupressaceae apparently possess a proliferation of axillary structures in their cone scales. In our interpretation, in Glyptostrobus each bract of both typical and atypical seed cones bears two descending accessory shoots, interpreted here as seed scales (ovuliferous scales). The primary seed scale is fertile and forms the ovules, the second is sterile and forms characteristic tooth-like structures. The bract and the two axillary seed scales are each supplied with a single distinct vascular bundle that enters the cone axis as a separate strand; this vasculature also characterises the descending accessory short shoots in the vegetative parts of the crown. In wild-type seed cones, the fertile seed scale is reduced to its ovules, and the ovules are always axillary. In contrast, the ovules of some of the teratological seed cones examined were located at the centre of the cone scale. An additional tissue found on the upper surface of the sterile lower seed scale is here interpreted as the axis of the fertile seed scale. Thus, the central position of the ovules can be explained by recaulescent fusion of the upper fertile and lower sterile seed scales. In several teratological cone scales, the ovules were enveloped by an additional sterile tissue that is uniseriate and represents an epidermal outgrowth of the fertile seed scale. Close to the ovules, the epidermis was detached from lower tissue and surrounded the ovule completely, except at the micropyle. These teratological features are potentially significant in understanding seed-cone homologies among extant conifers.

A note on a seed sterile nutmeg from the secondary center of domestication

A unique nutmeg accession having normal fruit, but with rudimentary, sterile seed and finely packed mace having a human brain like appearance was collected from a farmer’s garden from the secondary center of domestication of the crop and characterized. Seed (female) sterility in a dioecious or emerging monoecious plant like nutmeg is hitherto not recorded and is a novelty. This unique accession is conserved at the germplasm conservatory of tree spices at the ICAR-Indian Institute of Spices Research, Kozhikode, Kerala.

Serotiny in southern hemisphere conifers

Serotiny is a widespread trait in angiosperms in the southern hemisphere; however, it is less common in conifers and has been little examined in the only two genera of southern conifers (Callitris and Widdringtonia) that have serotinous cones. There is variation across the family in the size of cones, the amount of seed contained and the time over which the cones stay closed on the plant. Cones from most of the species were collected in the field and various morphometric measurements made including cone wet and dry weight, the number of seeds contained and their likely viability. Cones from a selection of species with different cone sizes were heated to increasing temperatures, to investigate the ability of cones to protect the contained seeds from heat. In comparison to the flowering plants, serotiny has developed comparatively recently in southern conifers (in the last 10–20 million years). In Widdringtonia, serotiny is relatively weak, whereas in Callitris, it varies from strong to non-existent. Cone size and fertile-seed production across the two genera varies and the number of fertile seeds produced is positively related to the size of the cone. In some species, there are sterile seed-like bodies. These may have developed to confuse seed predators, so fertile seeds have a better chance of survival. Larger (heavier) cones are more effective in protecting the contained seeds from the heat of fires than are smaller ones. There is no simple relationship between the cone size and type of environment occupied by the species. In regions where fire is unlikely, predictable but mild or completely unpredictable, the species tend to be non-serotinous. In temperate regions where hot fires are likely to have been a selective agent, the species tend to be more strongly serotinous, although fire is not essential to open the cones. The community and environment in which a species has evolved is likely to have influenced the development of the degree of serotiny for each species and this may still be a variable property among populations of some species, depending on the fire regime of the area in which they grow.

Seed cone traits and insect damage in Tsuga canadensis (Pinaceae)

We measured seed cones of Tsuga canadensis (L.) Carrière, assessed seed potential (number of fertile scales × 2) and seed efficiency (number of filled seeds/seed potential), and estimated the impact of Eupithecia mutata Pearsall (Lepidoptera: Geometridae) and Megastigmus hoffmeyeri Walley (Hymenoptera: Torymidae) on seed production. Mean length, width, and volume of healthy cones varied little among sites from Ontario. Cones had about 28 scales; 13 were sterile. Seed potential and seed efficiency differed among sites, ranging from 25 to 31 ovules and 24% to 72%, respectively. The number of scales (both sterile and fertile) increased with cone volume, but the proportion of fertile scales was independent of cone size. The maximum proportion of cones infested by E. mutata was 21%. On average, each larva destroyed >90% of the filled seeds from each cone, thus from a practical perspective, the proportion of T. canadensis seeds destroyed per site was equivalent to the proportion of seed cones infested. The proportion of cones infested by M. hoffmeyeri ranged from 9% to 40%, but the proportion of seeds destroyed per site (range: 1.1%–6.1%) was much lower than that of E. mutata. The maximum number of M. hoffmeyeri-infested seeds per cone was seven. To our knowledge, this is the first report documenting cone traits of T. canadensis and the impact of E. mutata and M. hoffmeyeri.

053 CLONAL DECLINE IN HORTICULTURAL CROPS DUE TO MULLER'S RATCHET

It should be possible to maintain horticultural clones unchanged forever through asexual generations, as commercial propagators and clonal repositories maintain clonal integrity, disease-free stock plants, or remove mutations. However, unintentional selection for nonhorticultural traits could still be occurring. Accumulations of such traits would be due to the operation of Muller's ratchet and include fertility losses, increases in virus titer, and stunted growth habit. In chrysanthemums, Dendranthema grandiflora. clones separated from sexual cycles for generations become increasingly sterile. Seed set across years, using coefficients of crossability (FCC/MCC), was examined for garden clones (forced through sexual cycles annually) and greenhouse clones (asexual cycles only). Garden clones 40 years old (54-101-11) had only depressed levels of fertility. In other cases (77-AM 3-17), the ratchet was reversed >1 sexual cycle. Greenhouse clones were often completely sterile since their propagation is primarily asexual.