Schriften zu Genetischen Ressourcen - Genres
Share Embed Flag
Download ePaper

Schriften zu Genetischen Ressourcen - Genres

Schriften zu Genetischen Ressourcen - Genres Schriften zu Genetischen Ressourcen - Genres

genres.de
30.11.2012 Views

Necessity of development of systematics of cultivated plants T. SMEKALOVA VAVILOV was one of the first to declare the necessity of complex investigations of species. However, the possibilities of systematics of cultivated plants have increased considerably since that time. Along with classical morphological, anatomical, and biological methods, new methods such as electron microscopy, biochemistry, and genetics, are now at the disposal researchers. These allow elaboration of controversial items in systematics in more detail. The enlargement of capabilities for use of original materials in breeding programmes for different crops brings with it the necessity of further development of systematics to a new, up-to-date level, including the use of recent achievements in several fields of biological sciences. On the other hand, the creation of a network of national and international genebanks demands special, stringent requirements for the correct systematisation (classification and nomenclature) of the material kept, and for the observation of the international nomenclature rules. Practical experience shows that neglecting these rules will inevitably lead to errors, which result in loss of material. For example, some American genebanks, when accessioning germplasm, use only the genus and species names together with a system of “descriptors”, which represents characters by coding them as numerical symbols (scores): A – Seed colour: (white – 0; red – 1; yellow – 2; etc). B – Seed shape: (oval – 0; oblong – 1; round – 2; etc). D – Leaf hairiness: (yes – 0; no – 1; etc). The nomenclatural combination is often reduced to the Latin name of the genus, for example, oats – Avena spp. An obvious imperfection of this registration system lies in the danger of merely mechanical mixing-up of figures, and in this case, any error is difficult to recognise immediately, and one error would lead to others. We can see an example of this kind of mistake on the cover of the “Report of a Working Group on Avena” (MAGGIONI et al. 1998), which shows a picture of an accession named ‘Creole’ (France) with yellow seeds, but actually this variety has black seeds. Furthermore, if a genebank curator is not very experienced, he may have difficulties with the coding of a character (e.g., oval vs. elongate; oval vs. roundish, etc.). Taxonomic disagreements are a great obstacle for the work of both genebanks and the systematics of cultivated plants as a whole. The underlying reason for such disagreements are different views on the circumscription, structure and criteria of species and intraspecific taxa. As MAYR (1973) noted, “In taxonomy we have almost unlimited differences of opinions on different problems”. Thus, different experts have 65

Development of Vavilov’s concept of the intraspecific classification of cultivated plants recognised within the genus Triticum from one (LÖVE 1984) to 40 and more species (BOWDEN 1959). In another case, two hexaploid oat species, Avena sativa and A. byzantina, are distinguished by a number of morphological, geographical and ecological characters, but on the other hand, they have two parallel sets of similar morphological characters (cf. Tab. 1). The curators of the oat collection of the Vavilov Institute recognise them as distinct and separate species (RODIONOVA 1994), while LADIZINSKY (1996) considers them as a single species, A. sativa. As a result, the same sample from the same collection site may be classified as different species in different genebanks. Tab. 1: Similarities and distinctions between two Avena species Species Morphological Traits Ecological Geographical Avena sativa L. • complex of traits charac- mesophyte Northern Europe teristic for each species; A. byzantina C. Koch • parallel rows of similar traits within both species xerophyte Southern Europe (Mediterranean) What is necessary to develop the systematics of domesticated plants? 1. To study the complexities of species using all methods including biochemical analyses, electron-microscopy, genetics, etc., as advocated by VAVILOV; 2. To evaluate the possibilities for gene transfer and thus use more sources for breeding: 3. To correct the nomenclature in order to improve the maintenance of samples in genebanks; 4. To analyse the reasons and sources for disagreements between taxonomists and to strive for agreement. The Vavilov Institute of Plant Industry maintains and develops traditions of biosystematics (differential systematics) of cultivated plants. In particular, the systematics of several genera, species and subspecies of the family Fabaceae have been elaborated in recent years (Cicer L., Lathyrus L. subgen. Cicercula (Medik.) Czefr., Vicia sativa L., etc.). When elaborating the systematics of the subgenus Cicercula of the genus Lathyrus, in addition to the basic morphological-geographical method, a number of other methods have been used such as electron microscopy, anatomy, and biochemistry. The 66

Development of Vavilov’s concept of the intraspecific classification of cultivated plants<br />

recognised within the genus Triticum from one (LÖVE 1984) to 40 and more species<br />

(BOWDEN 1959).<br />

In another case, two hexaploid oat species, Avena sativa and A. byzantina, are distinguished<br />

by a number of morphological, geographical and ecological characters,<br />

but on the other hand, they have two parallel sets of similar morphological characters<br />

(cf. Tab. 1). The curators of the oat collection of the Vavilov Institute recognise them<br />

as distinct and separate species (RODIONOVA 1994), while LADIZINSKY (1996) considers<br />

them as a single species, A. sativa. As a result, the same sample from the same<br />

collection site may be classified as different species in different genebanks.<br />

Tab. 1: Similarities and distinctions between two Avena species<br />

Species<br />

Morphological<br />

Traits<br />

Ecological Geographical<br />

Avena sativa L. • complex of traits charac- mesophyte Northern Europe<br />

teristic for each species;<br />

A. byzantina C.<br />

Koch<br />

• parallel rows of similar<br />

traits within both species<br />

xerophyte<br />

Southern Europe<br />

(Mediterranean)<br />

What is necessary to develop the systematics of domesticated plants?<br />

1. To study the complexities of species using all methods including biochemical<br />

analyses, electron-microscopy, genetics, etc., as advocated by VAVILOV;<br />

2. To evaluate the possibilities for gene transfer and thus use more sources for<br />

breeding:<br />

3. To correct the nomenclature in order to improve the maintenance of samples in<br />

genebanks;<br />

4. To analyse the reasons and sources for disagreements between taxonomists and<br />

to strive for agreement.<br />

The Vavilov Institute of Plant Industry maintains and develops traditions of biosystematics<br />

(differential systematics) of cultivated plants. In particular, the systematics of<br />

several genera, species and subspecies of the family Fabaceae have been elaborated<br />

in recent years (Cicer L., Lathyrus L. subgen. Cicercula (Medik.) Czefr., Vicia<br />

sativa L., etc.).<br />

When elaborating the systematics of the subgenus Cicercula of the genus Lathyrus,<br />

in addition to the basic morphological-geographical method, a number of other methods<br />

have been used such as electron microscopy, anatomy, and biochemistry. The<br />

66

logo

products

Resources

Company

Terms of service
Privacy policy
Cookie policy
Cookie settings
Imprint
Change language
Made with love in Switzerland
© 2024 Yumpu.com all rights reserved

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!