Jeffrey G. Boersma

Aligning a New Reference Genetic Map of Lupinus angustifolius with the Genome Sequence of the Model Legume, Lotus japonicus

We have developed a dense reference genetic map of Lupinus angustifolius (2n = 40) based on a set of 106 publicly available recombinant inbred lines derived from a cross between domesticated and wild parental lines. The map comprised 1090 loci in 20 linkage groups and three small clusters, drawing together data from several previous mapping publications plus almost 200 new markers, of which 63 were gene-based markers. A total of 171 mainly gene-based, sequence-tagged site loci served as bridging points for comparing the Lu. angustifolius genome with the genome sequence of the model legume, Lotus japonicus via BLASTn homology searching. Comparative analysis indicated that the genomes of Lu. angustifolius and Lo. japonicus are highly diverged structurally but with significant regions of conserved synteny including the region of the Lu. angustifolius genome containing the pod-shatter resistance gene, lentus. We discuss the potential of synteny analysis for identifying candidate genes for domestication traits in Lu. angustifolius and in improving our understanding of Fabaceae genome evolution.

A survey of wildflower farms in the south-west of Western Australia for Phytophthora spp. associated with root rots

A survey of wildflower farms in the south west of Western Australia, was conducted during spring of 1997 and autumn 1998 to determine the prevalence of Phytophthora infestations. Thirty-seven randomly selected farms ranging in size from 0.5 to =30 ha were visited. The main crop plants grown included species of Banksia, Boronia, Chamelaucium, Conospermum, Eucalyptus, Protea, and Leucadendron. Eighteen sites were found to have infestations of Phytophthora. Of these, 14 sites had P. cinnamomi, and 2 sites had P. cryptogea. P. cactorum, P. citricola and P. nicotianae were each found at only single locations. One site was found to have both P. cinnamomi and P. cryptogea. Species of Phytophthora were identified morphologically, isozymically, and using species-specific PCR primers. Not every species could be identified by all 3 methods. There was no apparent association between geographical location and the occurrence of Phytophthora spp.

Development of two sequence-specific PCR markers linked to the le gene that reduces pod shattering in narrow-leafed Lupin (Lupinus angustifolius L.)

Wild types of narrow-leaf lupin (Lupinus angustifolius L.) have seed pods that shatter upon maturity, leading to the loss of their seeds before or during the harvest process. Two recessive genes have been incorporated into domesticated cultivars of this species to maximize harvest-ability of the produce. One of these genes is called lentus (le). Two microsatellite - anchored fragment length polymorphism (MFLP) candidate markers were identified as closely linked to the le gene in a recombinant inbred line (RIL) population derived from a domesticated x wild type cross. The candidate MFLP markers were isolated from the gel, re-amplified by PCR, cloned and sequenced. The MFLP polymorphisms were converted into sequence-specific PCR-based markers. Linkage analysis by MapManager indicated that one of the markers, LeM1, was 2.6 centiMorgans (cM) and the other, LeM2, was 1.3 cM from the gene, with both being on the same side. The correlation between the marker genotype and the plant phenotype for the le gene is 95% for the Australian cultivars, and approximately 36% on wild types tested. These markers may be useful in marker assisted selection for the le gene when introgressing wild material into lupin breeding programs.

Identification of quantitative trait loci (QTLs) influencing early vigour, height, flowering date, and seed size and their implications for breeding of narrow-leafed lupin (Lupinus angustifolius L.)

We report the first quantitative trait loci (QTL) mapped in an F8 recombinant inbred line (RIL) population of Lupinus angustifolius. Traits mapped were early vigour, days to flowering, height at maturity, and seed size. Twenty-two QTLs were found, located on 13 linkage groups, with alleles beneficial to the crop contributed by both parents. Early vigour was controlled by 8 QTLs on 7 linkage groups. Time to flowering was controlled by 10 QTLs and the height at maturity was found to be under the control of 4 QTLs. Seed size was linked to 2 QTLs. A region linked to the Ku gene that promotes early flowering by removal of the vernalisation requirement appeared to play a role in all 4 traits. The gene mollis controlling soft-seededness appeared to also be linked to early vigour, and iucundis controlling alkaloid production was linked to seed size. Five pairs of QTLs were found to be involved in epistasis, 2 of these having an effect on early vigour and another 3 influencing the time to opening of the first florets. Variation explained for each trait ranged from 28% for seed size, to 88% for days to flowering. We showed that it was possible to use these data to predict genotypes of superior progeny for these traits under Mediterranean conditions. QTL regions were compared on a second published linkage map and regions of conserved synteny with the model legume Medicago truncatula highlighted.