Hybrid Tea-rose pollen. II. Inheritance of pollen viability

Summary Pollen viability was evaluated in about 500 seedlings originating from 31 crosses between nine commercial Hybrid Tea-rose varieties. The data indicated that pollen viability was inherited additively.     

The effect of alternating temperatures on the self-incompatibility of some clones of Brussels sprouts (Brassica oleracea L. var. Gemmifera (DC.) Schulz)

Summary The influence of temperature on self-incompatibility of six S-homozygous clones of Brussels sprouts was studied. The clones were treated with constant temperatures of 14°, 17° and 20°C and alternating day and night temperatures of 17/14°, 20/14°, 23/14° and 26/14°C. To determine the degree of incompatibility the mean number of pollen tubes per style after selfing was calculated.The clone with the weak S-allele S-5 was less self-incompatible in the 23/14° and 26/14°C treatments than in the other treatments. The other clones with the weak S-alleles S-15 and S-45 remained sufficiently self-incompatible during all treatments. The clone with the rather strong S-39 showed the highest level of self-incompatibility at 26/14°C.In the two weakly self-incompatible clones with S-5 and S-39 a clear difference in self-incompatibility was found between young and old flowers. The strongly SI clones with S-39 showed no difference and in the two clones with S-15 the differences were small and significant in one case only.     

A comparison of apple and pear seedlings with reference to the juvenile period. II. Mode of inheritance

Summary Analysis of two incomplete half-diallel schemes of crosses, involving 22 apple and 33 pear progenies with 2500 and 5400 seedlings respectively, showed a highly significant GCA and an insignificant SCA variance for the juvenile period (J.P.). This indicates that the inheritance of the J.P. is of an additive nature, a mode of inheritance which is a function of the inheritance of a complex of factors governing growth. The mean J.P. of apple progenies varied between 3.4 and 5.0 years, that of pear progenies between 4.7 and 7.0 years. The implications for breeding are discussed.Also presented at the Juvenility Symposium held at West-Berlin, November 1976.     

Pre-selection of compact mutants induced by X-ray treatment in apple and pear

Summary Mutation breeding of apple and pear started in 1965 using dormant scions which, after irradiation (X-rays), were grafted on rootstocks. The most efficient dose for apple was around 3 krad, for pear between 4.5 and 7 krad. Primarily shoots exhibiting compact traits were selected, defining such shoots as being thicker than normal for their length or shorter than normal for their diameter while having shorter internodes than normal shoots. The selection was carried out on one-season-old shoots of the same trees during three successive seasons, this involved a cut back at the end of the first and second season. The selected compact shoots yielded with apple on average four times more clones with a distinct compact habit than normal appearing shoots; four out of every five clones were found to be stable in both apple and pear. Averaging the results for apple, 7% of the surviving trees produced shoots the clones of which showed compact growth, this was only 0.5% for pear. In all several dozens of such clones were obtained of the apple varieties Golden Delicious, Cox's Orange Pippin, Belle de Boskoop and Tydeman's Early and a few distinct compact and some dwarf clones of Beurré Hardy and Doyenné du Comice.Samenvatting Mutatieveredeling bij appel en peer begon in 1965 met enthout dat, na bestraling, op onderstam werd geënt. De doelmatigste dosering lag bij appel om en nabij 3 krad, bij peer tussen 3, 5 en 7 krad, afhankelijk van het ras. De nadruk viel op de selectie van spur-scheuten cum scheuten met een gedrongen habitus. Zulke scheuten werden gedefiniëerd als scheuten die, afgaande op hun lengte, dikker zijn of, afgaande op hun diameter, korter zijn dan normaal terwijl in beide gevallen de internodiën korter zijn dan bij vergelijkbare normale scheuten.De selectie werd uitgevoerd op éénjarige scheuten van dezelfde geënte bomen gedurende drie achtereenvolgende seizoenen; dit hield in dat na het eerste en het tweede groeiseizoen werd teruggesnoeid. De geselecteerde appelscheuten gaven, na enting, viermaal meer klonen met een uitgesproken gedrongen habitus dan willekeurige normaaluitziende scheuten uit bestraald materiaal. Zowel bij appel als bij peer bleken vier van de vijf klonen stabiel te zijn. Bij appel produceerden gemiddeld 7% van de overlevende bomen klonen met een gedrongen groei, bij peer was dit slechts 0.5%.In totaal werden enige dozijnen klonen met gedrongen of zwakkere groei verkregen bij de appelrassen Golden Delicious, Cox's Orange Pippin, Belle de Boskoop en Tydeman's Early en slechts enkele bij de pererassen Beurré Hardy en Doyenné du Comice.Subcontract Institute for Atomic Sciences in Agriculture (ITAL), Wageningen, the Netherlands.     

Secondary somatic embryogenesis and applications in plant breeding

Summary Secondary somatic embryogenesis is the phenomenon whereby new somatic embryos are initiated from somatic embryos. Such cultures have been described in at least 80 Gymnosperm and Angiosperm species. In the initial step (primary somatic embryogenesis) such cultures have to be started from plant explants. In general, primary somatic embryogenesis from vegetative plant explants is, indirect and mostly driven by auxin (AUX) or auxin and cytokinin (AUX/CYT) supplemented media, whereas, from zygotic embryos it is direct and driven, to a larger extent, by CYT or growth regulator free media. Primary somatic embryogenesis from floral plant explants is between these two extremes. Indirect and direct somatic embryogenesis should be seen as two extremes of one continuum: in indirect somatic embryogenesis the embryos develop up to the (pre)-globular stage and in direct somatic embryogenesis to mature stages before they are subjected to secondary embryogenesis. In general, secondary embryogenesis requires no growth regulators in species with CYT driven primary embryogenesis. Whereas, continuous exposure to growth regulators is needed in species with CYT/AUX or AUX driven primary embryogenesis.In most species somatic embryos can be converted into shoots, although the frequencies are mostly low. In general, somatic embryos induced by growth regulator free or CYT supplemented media meet more difficulties in shoot development than embryos induced by AUX supplemented media. Applications of secondary somatic embryogenesis for plant breeding are discussed.     

The performance of double or mixed pollinations with compatible and self-incompatible or incongruous pollen of pear and apple

Summary Six pear and five apple trials were carried out to ascertain the outcome of combinations of compatible pollen (C) with self (S) or incongruous pollen (I) as to the pollination index (PI=seeds/pollinated flower). The PI of the mixture C+I (1:5) was consistently depressed as compared to that of the control C. The results of the double pollinations S/C and I/C were affected by the temperature at pollination; their PI's at <15°C were twice as high as those at >15°C, being well above and below the PI of C in the former and latter case respectively. The opposite was true for the C/S combination, the PI of which increased with the pollination temperature; the PI of C/I did not differ much from the PI of C, irrespective of temperature. The conclusion was reached that the interaction previously and presently found between compatible and self-incompatible pollen also exists to a fair extent between compatible and incongruous pollen. However, in pear neither the mentor nor the pioneer pollen technique proved to aid its hybridization with apple, the formation of self seed was not observed either. In apple the production of apple × pear hybrids was likewise doubtful, but the double pollinations S/C and C/S formed 4–10% self seed.     

Avenin diversity analysis of the genus Avena (oat). Relevance for people with celiac disease

Oat is widely consumed by people with celiac disease (CD). Its safety has been disputed because two peptides from oat avenins can be recognized as T cell epitopes by some CD patients. Differential signals of gluten-specific monoclonal antibodies and in-vitro T cells to oat varieties have suggested the existence of differences in immunogenicity. We aimed to clarify the nature of such responses by cloning avenin genes from 13 Avena species. A single oat plant contained up to 10 avenin genes. Avenin proteins clustered in four groups of which two contained the two avenin CD epitopes. All Avena species examined harbored avenins of these two groups, and as a consequence all contained avenins with the two avenin-specific epitopes, which makes it very unlikely to find oat cultivars that are devoid of these sequences. The established gluten epitopes from wheat, rye and barley were not present in oat avenins; some variants with two and three amino acid substitutions occurred, but they were predicted not to resist proteolysis in the gastro-intestinal tract. Perfect recognition sites of antibodies R5 and G12 were also not present in avenins. Thus, their signals to oat should not be interpreted as differences in immunogenicity for CD patients.     

A survey of the skidder fleet of Central,Eastern and Southern Europe

European Journal of Forest Research - As a generalization, harvested timber is extracted from forests either as trees or stems by skidders or as logs by forwarders. Coupled with harvesters,...