Diversity in fertility potential and organo-sulphur compounds among garlics from Central Asia

Extending the collection of garlic (Allium sativum L.) accessions is an important means that is available for broadening the genetic variability of this cultivated plant, with regard to yield, quality, and tolerance to biotic and abiotic traits; it is also an important means for restoring fertility and flowering. In the framework of the EU project Garlic and Health, 120 garlic accessions were collected in Central Asia - the main centre of garlic diversity. Plants were documented and thereafter maintained in field collections in both Israel and The Netherlands. The collection was evaluated for biological and economic traits. Garlic clones vary in most vegetative characteristics (leaf number, bulb size and structure), as well as in floral scape elongation and inflorescence development. A clear distinction was made between incomplete bolting and bolting populations; most of the accessions in the latter populations produced flowers with fertile pollen and receptive stigma. Wide variations were recorded with regard to differentiation of topsets, their size, number and rapidity of development. Furthermore, significant variation in organo-sulphur compounds (alliin, isoalliin, allicin and related dipeptides) was found within garlic collections and between plants grown under differing environmental conditions. Genetic fingerprinting by means of AFLP markers revealed three distinct groups within this collection, differing also in flowering ability and organo-S content

Influence of the Environment on the Performance of some Onion Cultivars in Kenya

Eight introduced and three local onion ( Allium cepa ) cultivars were evaluated at four locations for two seasons in Kenya to determine genotype x environment interactions and stability for bulb yield and other agronomic characters. The genotype x environment interactions and stability were investigated by regression analysis. Genotypic effects were highly significant for all traits except days to maturity. Bulb yields for the 11 cultivars varied between 16.2 and 35.6 t ha-1; introduced cultivars out-yielded the local ones. Environment (E) and genotype (G) x environment interaction effects were highly significant for all traits. A considerable portion of genotype x environment interaction effects for bulb yield was linear. The significant G x E (linear) variance indicated that there were genetic differences among the cultivars in their response to the environment

Unlocking variability: inherent variation and developmental traits of garlic plants originated from sexual reproduction

Recent collections of fertile garlic (Allium sativum) accessions from Central Asia allow a detailed study of seedling developments and the evaluation of inherent variations. We hereby provide a comprehensive account of the ontogenesis of a population of garlic seedlings and their vegetative and reproductive traits. A nucleotide binding site profiling marker technology was applied to provide conclusive evidence for the cross-pollination nature of garlic, and to compare the levels of polymorphism between progeny derived from a single mother clone fertilized by several pollinators. The seedlings¿ population demonstrates a large variation in vegetative and reproductive characters, including bulbing ability, bulb color and size, clove number, and response to environmental conditions, similar to that of the genepool of vegetatively propagated garlic clones. In addition, a large variation in flowering and seed production ability was recorded. The understanding of garlic physiology, the availability of the large variability unleashed by sexual reproduction, and the possible utilization of sexual hybridization opens the way for genetic studies and breeding wor

Garlic (Allium sativum L.) and its wild relatives from Central Asia: evaluation for fertility potential

Garlic (Allium sativum L.) a popular condiment, is completely sterile, and thus is propagated only vegetatively. According to modern taxonomy, A. sativum and its closest wild relative A. longicuspis form a species complex. The collection of a large number of accessions of these taxa is the only means available for expansion of the genetic variability with regard to yield, quality, tolerance to biotic and abiotic traits, as well as flowering and possibly fertility restoration. A large number of garlic accessions was recently collected in Central Asia, the main center of garlic diversity. Plants were documented according to IPGRI rules, and thereafter evaluated and maintained in the field collections of vegetatively propagated alliums in Israel. The studied accessions were subdivided into two distinct sub-populations: semi-bolters and bolters. Most of flower-producing accessions produced both fertile pollen and receptive stigmas, and true garlic seeds were obtained from 5 accessions, collected in Kazakhstan in 1996-1998. The garlic inflorescence is an umbel-like structure with flower clusters (branches) arising from a common meristem. The flower morphology is typical of the genus Allium. Differentiation of topsets begins in the periphery of the apical surface only after floral differentiation has occurred, and the size, number and rapidity of topset development varies significantly between genotypes. Further studies of flowering physiology and fertility restoration, should focus on bolting genotypes which produce inflorescences with a high ratio of normal flowers to topsets

Garlic breeding system innovations

This review outlines innovative methods for garlic breeding improvement and discusses the techniques used to increase variation like mutagenesis and in vitro techniques, as well as the current developments in florogenesis, sexual hybridization, genetic transformation and mass propagation. Sexual sterility of garlic reduces its potential for improvement of desired traits. Restoring fertility in this crop, which has been vegetatively propagated for millenia, provides new genetic possibilities for breeding purposes and/or genetic studies. In this context the recent developments on the manipulation of garlic florogenesis are discussed and it is shown that specific environmental conditions might allow for fertility restoration and seed production in bolting garlic. Furthermore the introduction of Agrobacteriummediated and biolistic gene transfer systems in garlic, a species known for its recalcitrant behaviour in in vitro culture, are reviewed. Attention is paid to the development of a high quality callus year-round production method for transformation. Also the first garlic transgenics resistant to beet army worm (Spodoptera exigua) and herbicides will be introduced. Garlic friable embryogenic calluses are of pivotal importance for the establishment of cell suspension cultures needed for rapid multiplication of elite garlic genotypes. The development of these suspension cultures are discussed in this review. It is shown that a large number of somatic embryos (potentially 8 x 109 to 1011) can be produced annually, from a single clove, for each current variety and that the conversion into plantlets amounts approximately 50%. (Résumé d'auteu