Marker assisted selection for seedlessness in table grape breeding

Seedlessness is one of the most appreciated traits in the table grape (Vitis vinifera L.). The development of new seedless varieties is expensive and time consuming, involving the generation and selection of thousands of hybrids each year. In seeded × seedless crosses, seedlessness commonly segregates 1:1, so molecular markers allowing for the early identification of plants that will produce seedless berries are very useful. This early selection can lead to savings in maintenance and evaluation costs, and allows additional space for larger effective progenies. The variety Sultanina has been the main source of stenospermocarpic seedlessness in table grape breeding. In a previous work, we showed a 198-bp allele at the VMC7F2 microsatellite locus as a potential marker for selection of seedless genotypes due to its close linkage to the major effect seedless QTL, SDI. In this study, we show that stenospermocarpic bred cultivars share a main haplotype around this locus not found in seeded cultivars, which facilitating the development and use of marker assisted selection (MAS) strategies for the selection of seedless plants. In this way, VMC7F2 on its own can be a very useful marker for selecting seedless individuals from segregating crosses. A MAS program based on the presence of the 198-bp allele at VMC7F2 allows the reduction of the progeny size to 54%, selecting most of the seedless individuals. In addition, our results show the existence of other possible sources of stenospermocarpic seedlessness that could provide alternative sources of genetic variation for breeding of this trait. © 2012 The Author(s)

An integrated SSR map of grapevine based on five mapping populations

International audienceAbstract A grapevine (mainly Vitis vinifera L., 2n = 38) composite genetic map was constructed with CarthaGene using segregation data from Wve full-sib populations of 46, 95, 114, 139 and 153 individuals, to determine the relative position of a large set of molecular markers. This consensus map comprised 515 loci(502 SSRs and 13 other type PCR-based markers),ampliWed using 439 primer pairs (426 SSRs and 13 others)with 50.1% common markers shared by at least two crosses. Out of all loci, 257, 85, 74, 69 and 30 were mapped in 1, 2, 3, 4 and 5 individual mapping populations,respectively. Marker order was generally well conserved between maps of individual populations, with only a few signiWcant diVerences in the recombination rate of marker pairs between two or more populations. The total length of the integrated map was 1,647 cM Kosambi covering 19 linkage groups, with a mean distance between neighbour loci of 3.3 cM. A framework-integrated map was also built, with marker order supported by a LOD of 2.0. It included 257 loci spanning 1,485 cM Kosambi with a mean inter-locus distance of 6.2 cM over 19 linkage groups. These integrated maps are the most comprehensive SSR-based maps available so far in grapevine and will serve either for choosing markers evenly scattered over the whole genome or for selecting markers that cover particular regions of interest. The framework map is also a useful starting point for the integration of the V. vinifera physical and genetic maps

Cryoprotective dehydration: clues from an insect

Arthropods have evolved a number of different adaptations to survive extreme environmental temperatures including, in some regions, over-wintering temperatures well below 0°C. One of the less common adaptations to surviving cold is that of cryoprotective dehydration, where the animal becomes almost anhydrobiotic with the loss of virtually all osmotically active water. In this chapter, we describe integrated studies utilising physiology, biochemistry and molecular biology to understand this phenomenon in the Arctic springtail (Megaphorura arctica) (formerly Onychiurus arcticus). These studies concentrate on the action of trehalose as a cryoprotectant, the production of antioxidants to reduce cell damage and changes in membrane composition