The creation of tetraploid beets
SummaryIn recent years trial fields were laid out with tetraploid families of the sugar beet varieties SX and SY, the fodder sugar beet varieties VA and VB and the fodder beet varieties VC (high content) and VD (low content).It appeared that the tetraploid beets are morphologically distinct from the diploid commercial varieties in leaf form, leaf development, form of the beet, tendency to bolt, size of the clusters and the number of seedlings per cluster.The beets of all the plots are washed, weighed and measured for dry matter, sugar and crude protein content and seed for stecklings is sown on a separate trial field.From the results it appears that there is a variation in the above-mentioned contents so that it seems possible to improve the material by selection. This also holds for the dry matter production which agrees with that of diploid commercial varieties.The investigations are being continued.
The creation of tetraploid beets
SummaryIn 1950, 1951 and 1952 germinated seed of various sugar beet and fodder beet strains were treated with colchicine, with the object of obtaining tetraploid plants. The plants were examined cytologically in their first and second year. Only stalks of the C0 generation (the treated one) in which no diploid cells were found were kept for seed production.By raising the tetraploid C1 plants in greenhouses the year that the seed has been harvested and by vernalizing the young plants seed production is made annual. For vernalization the plants are kept in a potato storage room cooled by outside air to a temperature of about 5°C and under a day length of 24 hours.The results of the cytological examination demonstrated that collecting seed from tetraploid stalks of the C0 presents advantages. The C1 had about 77% tetraploids.It should be noted that the determination of the chromosome numbers of polyploid material is preferable to measurements of stomata or pollen grains as the latter are not reliable.The investigations are being continued. Yield trials with tetraploid material have been made by D. Kloen.SamenvattingIn 1950, 1951 en 1952 werd gekiemd zaad van verschillende suiker- en voederbietenrassen met colchicine behandeld. Het doel daarbij was tetraploiden te verkrijgen als uitgangsmateriaal voor verdere veredeling.In hun eerste en tweede levensjaar werden de planten (C0) cytologisch onderzocht. Er werd alleen zaad geoogst van stengels, waarin geen diploide cellen werden aangetroffen. Het geoogste zaad werd spoedig daarna in de kas uitgezaaid, teneinde nog in dezelfde herfst de tetraploiden te kunnen afzonderen. De duur van de selectie werd verkort door het aldus verkregen materiaal te vernaliseren. Hierdoor werd de zaadteelt eenjarig gemaakt.In 1951 werd zaad geoogst van alle aanwezige C0 stengels, terwijl slechts één of enkele werden onderzocht. In 1952 daarentegen werd alleen zaad geoogst van stengels, waarin bij cytologisch onderzoek geen diploide cellen werden aangetroffen. Het percentage tetraploiden in de C1 was in het eerste geval ± 53%, in het tweede geval ± 77%.Het vaststellen van het chromosomenaantal is te verkiezen boven het verrichten van metingen aan stomata en pollenkorrels, aangezien dit materiaal niet altijd betrouwbaar is.Het onderzoek wordt voortgezet. Getracht zal worden het percentage tetraploiden te vergroten. Met het beschikbare tetraploide materiaal zijn door D. Kloen voorlopige opbrengstproeven genomen.
Genetics of the phenotypic evolution in sheep: a molecular look at diversity-driving genes
Background After domestication, the evolution of phenotypically-varied sheep breeds has generated rich biodiversity. This wide phenotypic variation arises as a result of hidden genomic changes that range from a single nucleotide to several thousands of nucleotides. Thus, it is of interest and significance to reveal and understand the genomic changes underlying the phenotypic variation of sheep breeds in order to drive selection towards economically important traits. Review Various traits contribute to the emergence of variation in sheep phenotypic characteristics, including coat color, horns, tail, wool, ears, udder, vertebrae, among others. The genes that determine most of these phenotypic traits have been investigated, which has generated knowledge regarding the genetic determinism of several agriculturally-relevant traits in sheep. In this review, we discuss the genomic knowledge that has emerged in the past few decades regarding the phenotypic traits in sheep, and our ultimate aim is to encourage its practical application in sheep breeding. In addition, in order to expand the current understanding of the sheep genome, we shed light on research gaps that require further investigation. Conclusions Although significant research efforts have been conducted in the past few decades, several aspects of the sheep genome remain unexplored. For the full utilization of the current knowledge of the sheep genome, a wide practical application is still required in order to boost sheep productive performance and contribute to the generation of improved sheep breeds. The accumulated knowledge on the sheep genome will help advance and strengthen sheep breeding programs to face future challenges in the sector, such as climate change, global human population growth, and the increasing demand for products of animal origin.