Kalloo / Bergh Genetic Improvement of Vegetable Crops

1. Auflage 2012
ISBN: 978-0-08-098466-7
Verlag: Elsevier Science & Techn.
Format: EPUB
Kopierschutz: 6 - ePub Watermark

E-Book, Englisch, 846 Seiten

Genetic improvement has played a vital role in enhancing the yield potential of vegetable crops. There are numerous vegetable crops grown worldwide and variable degrees of research on genetics, breeding and biotechnology have been conducted on these crops. This book brings together the results of such research on crops grouped as alliums, crucifers, cucurbits, leaf crops, tropical underground and miscellaneous. Written by eminent specialists, each chapter concentrates on one crop and covers cytology, genetics, breeding objectives, germplasm resources, reproductive biology, selection breeding methods, heterosis and hybrid seed production, quality and processing attributes and technology. This unique collection will be of great value to students, scientists and vegetable breeders as it provides a reference guide on genetics, breeding and biotechnology of a wide range of vegetable crops.

Autoren/Hrsg.

Kalloo, G.

Bergh, B. O.

Leseproben

1

Chive

L.

T. TATLIOGLU

Publisher Summary

Allium schoenoprasum is a member of the section schoenoprasum of the genus Allium. The natural habitats of Allium schoenoprasum are Asia, Europe, and Northern America, including the Arctic. In Europe, it has been used as a spice ever since the early Middle Ages at the latest. The leaves of chives are used as appetizing condiment in soups, cooked meals, salads, and also as sandwich filling. In Siberia, salted chives are stored for winter use. Allium schoenoprasum belongs to the permanent cultures and grows on practically all soils, which are not too poor or dry. The spicy flavor of chives is caused by the content of garlic oil. It contains relatively high amounts of vitamin C, carotin, and calcium. This chapter discusses the cytology and genetics of Allium schoenoprasum. Breeding objectives in chives are forcing ability, homogeneous growth, tillering ability, desired leaf diameter, late flower formation in forcing, upright leaf position, and yield. The minor role of Allium schoenoprasum on a world scale and the known diversity of this crop reduce the necessity for large collections. The chapter presents the existing collections. It reviews the reproductive biology of Allium schoenoprasum, its varieties, and breeding methods.

is a member of the section of the genus The genus L. is recognized to have more than 600 species.23 Besides , there are other species important for human nutrition in the section , like (onion), (Welsh onion), and (shallot).

The natural habitats of are Asia, Europe and Northern America including the Arctic. Presumably, it came from Central Asia or the Mediterranean and spread across Europe up to the 70th degree of latitude, across Middle Eastern and Northern Asia as well as across Northern America up to the Arctic area as a wild plant. The cultivated form appears to have been domesticated on numerous occasions. No major selective forces appear to have been applied and there is a wide variation in the cultivated forms, with hybridization between cultivated and wild types.

In Europe it has been used as a spice ever since the early Middle Ages at the latest. The leaves of chives are used as appetizing condiment in soups, cooked meals, salads and also as sandwich filling. It is used in the kitchen at any time. In Siberia, salted chives are stored for winter use. It belongs to the permanent cultures and grows on practically all soils, which are not too poor or dry. The spicy flavour of chives is caused by the content of garlic oil. It contains relatively high amounts of vitamin C, carotin and calcium.

In Central Europe, is sown in February/March in the greenhouse or in cold frames. At the end of April to beginning of May it is planted into the field. In climatically favourable areas direct sowing is possible in March/April, or in July, respectively. Under field conditions in Central Europe, chives start a preceding rest period at the end of August to the beginning of September. Then, plant growth is reduced, the leaves discolour and finally dry up, so that they do not meet market quality any longer. The preceding rest period lasts until about mid-October, depending on water supply, followed by the actual rest period. During the preceding rest period, carbohydrates of the leaves are translocated into the bulbs and roots.9 In forcing, carbohydrates are the nutrition of the young leaves. If the rest period is not artificially broken, the actual rest period of chives lasts 4–5 weeks at least, so that forcing can start at the end of November at the earliest. Then, market can be supplied with forced chives at the end of December. In order to be able to supply market four weeks earlier, the rest period is generally broken at the end of October by warm water treatment.6,7 Chives are marketed either in pots or cut in bunches. From July until October the market is generally supplied from field cuttings.

The main marketing area in Europe is Germany. If the cultivated area in private gardens is not considered, the total cultivated area for field harvest and for production of forced chives in Germany may amount to about 250 ha. The whole national volume of economic activity of chives amounts to about 200 million DM. Within this volume of economic activity the portion of field cutting is about 10%. In Denmark, field cultivation of about 50 ha is mainly for deep freezing industry. Besides Germany and Denmark, chives keep gaining importance in other European countries like Holland, Sweden, England, and France.

Cytology

Most origins of are diploid with a chromosome number of 2 = 16.10 The tetraploid origins (2 = 36) are mostly from Siberia.10 Crosses between morphologically considerably differing tribes with the same chromosome number are easy. Thus, all morphological transitions can be found in nature. Crosses between tetraploid and diploid origins are successful only if the tetraploid partner is used as female.10

The eight pairs of chromosomes investigated on natural populations from continental Europe and Britain ranged in size from 5.6 µm to 8.3 µm at colchicine metaphase.14 Chromosome pairs 1–7 were metacentric, while pair 8 was acrocentric carrying the nuclear-organizer region. During normal male meiosis the eight bivalents usually had a total of between 15 and 17 non-localized chiasmata. The size of chromosomes investigated in var. of 7 Western Canadian populations ranged from 6.5 µm to 7.6 µm and the average chiasmata frequency per bivalent was 2.1.5

In from Botanic Gardens, which was not more closely defined,50% of the chiasmata were proximal, 48% distal terminal and only 2% median. Pairing started either distally or proximally, but in the latter case distal secondary points obtained a higher chiasmata frequency.24

In some populations also plants with B-chromosomes can be found.14,5 The B-chromosomes in are quite stable during meiosis.2,8

Stevens and Bougourd14 reported high levels of karyotypic heterogeneity in natural populations from Britain and continental Europe. Meiotic analysis of 1017 plants revealed that 35 (3.4%) were heterozygous for one or more major structural chromosome mutations. This variability is superimposed on a karyotype that appears to be fundamentally stable over a wide geographic range.14

C-banding patterns in were described by Vosa25 from European plants, and by Cai and Chinnappa3 and by Tardif and Morisset15 from North American plants. These three studies produced very different results, which were interpreted as a consequence of genetic divergence between European and North American populations and by the different denaturing agents used in the experiments.3 Between as well as within the populations there is a remarkable variation in the occurrence of C-bands.15

Genetics

The economic importance of chives is quite small compared to some other vegetable plants. This may be the reason why the number of genetic studies on this plant species is relatively small.

In there is a well defined cms-system, in which concerning the mitochondrial (mt) genome two different cytoplasms, (S) for male sterility, (N) for male fertility, and three nuclear genes are involved. The male sterility caused by the (S) cytoplasm is reversed by the dominant restorer gene , so that only plants of the genetic constitution (S) are male sterile.16 The dominant temperature gene functions like a restorer gene, but only under high constant temperatures of 24°C20 [constitution of temperature sensitive cms plants: (S) or (S)]. The recessive gene is responsible for tetracycline sensitivity of the cms in chives.18,22 Plants, which are sensitive to tetracycline [(S))] have a reversible fertility after treatment with tetracyclines.19 Fertility due to high temperatures is reversible too.17

The mt-DNA of the (S) and (N) cytoplasms considerably differ from each other. The mitochondria of the (S) cytoplasm synthesizes an additional polypeptide of the molecular weight 18 kd. The synthesis of this polypeptide is inhibited by the restorer gene 11 Besides the (N) and (S) cytoplasms, eight other cytoplasms are characterized in chives, considerably differing from each other in their mt-genome. Their relation to male sterility has not yet been established.

In chives, there are four other types of male sterility, which have come up in different varieties or breeding lines. Other nuclear genes not identical with the gene are involved in their inheritance. One of these nuclear genes even causes male sterility in the (N) cytoplasm. It has not been finally established whether these new forms are genic or cytoplasmic male sterility.

Stevens and Bougourd12 described three diallelic genes involved...