Genetic Characterization of an Unknown Chinese Bulbous Leek-like Accession and its Relationship to Similar Allium Species

Autor: Michael J. Havey, Predrag Šesek, Borut Bohanec, Marijana Jakše
Rok vydání: 2005
Předmět:
Zdroj: HortScience. 40:1690-1694
ISSN: 2327-9834
0018-5345
DOI: 10.21273/hortsci.40.6.1690
Popis: Bulbous leek-like plants are a poorly defi ned group usually assigned to the Allium ampeloprasum complex. Studies were initiated to determine the origin of an unusual bul- bous accession received in Shanxi province in China, where it was used in diet as garlic but propagated by seeds, and to genetically compare this accession with morphologically similar plants from Europe. Genetic analyses included karyotypes and genomic in situ hybridiza- tion, pollination to leek, genome size determination and nuclear rDNA and plastid DNA polymorphisms. Results revealed that this agriculturally interesting accession from China is a so far unknown variant within tetraploid A. ampeloprasum cultivated taxa. We also observed that great-headed garlic did not share derived states in the chloroplast with leek, revealing that this cultivated plant does not possess the cytoplasm of leek or garlic, while its 1C genome size was 17% bigger than those of studied leek and bulbous-leek accessions. The genus Allium L. contains about 700 species, several of which are edible and are among man's most ancient cultivated crops. The edible alliums and their areas of cultivation have been recently reviewed by Fritsch and Friesen (2002). The large number of Allium species and the diversity among the cultivated forms, which are spread across diverse climates throughout the Northern hemisphere, permits for the occasional discovery of new cultivated forms, not yet well described. Most botanical classifi cations of species were based on mor- phological characterizations, however modern genetic techniques can provide new insights regarding phylogenetic relationships. Major crops within subgenus Allium section Allium are A. sativum L. (garlic) and the various cultivated forms of A. ampeloprasum L. Ac- cording to Mathew (1996), A. ampeloprasum is widespread through out the Mediterranean region and Middle Eastern countries; however, populations have been recorded in other areas possibly due to ancient introductions. Using the botanical terminology of Matthew (1996), wild A. ampeloprasum is thought to be the progenitor form of crop plants A. porrum L. (leek) and A. kurrat Schweinf., both cultivated for their leaves. A third variant, termed great- headed garlic, is cultivated for its bulbs and asexually propagated. Mathew (1996) states that great-headed garlic closely resembles A. ampeloprasum and does not warrant classifi - cation as a separate species. Mathew (1996) also described A. commutatum Guss. and A. bourgeaui Rech. as closely related to A. ampeloprasum. Similarly Brewster (1994), following the classifi cation proposed by Hanelt (1990), cites two major crop species within subgenus Allium section Allium: A. sativum (garlic) and A. ampeloprasum classifi ed into the four horticultural groups of leek, kurrat, great-headed garlic and pearl onion. Based on their use, Messiaen et al. (1993) classifi ed leek-like plants as A. polyanthum Schultes, A. ampeloprasum (sensu stricto), A. com- mutatum and A. scorodoprasum L.. These authors mention that wild A. ampeloprasum var. bulbiferum (from Yeu Island, off Western France) and Great Headed Garlic are chemi- cally closer to garlic. The ploidy levels of bulbous leek-like plants are highly variable. As recently reviewed by Mathew (1996), the chromosome numbers of A. ampeloprasum ranged from 16 to 56, A. porrum from 32 to 48, A. kurrat at 32, A. com- mutatum from 16 to 48, and A. polyanthum at 32. The predominant ploidy level among these species is tetraploid (32), while other ploidies are less frequent and may be associated with vegetative propagation. Allium ampeloprasum, A. porrum and A. commutatum may possess variable numbers of B chromosomes. Our studies focused on the genetic char- acterization of economically useful forms of bulbous alliums with leaf morphologies similar to leek. We concentrated on an unusual accession received in Shanxi province, China, where it is seed propagated but used in diets as garlic. Studies included the majority of mor- phologically similar alliums, using karyotype analysis, genomic in situ hybridization (GISH), pollination, genome size determination and molecular markers using nuclear rDNA and plastid cpDNA probes.
Databáze: OpenAIRE
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