Innovative transcriptome-based genotyping highlights environmentally responsive genes for phenology, growth and yield in a non-model grain legume.

The narrow-leafed lupin, Lupinus angustifolius L., is a grain legume crop, cultivated both as a green manure and as a source of protein for animal feed and human food production. During its domestication process, numerous agronomic traits were improved, however, only two trait-related genes were identified hitherto, both by linkage mapping. Genome-wide association studies (GWAS), exploiting genomic sequencing, did not select any novel candidate gene. In the present study, an innovative method of 3'-end reduced representation transcriptomic profiling, a massive analysis of cDNA ends, has been used for genotyping of 126 L. angustifolius lines surveyed by field phenotyping. Significant genotype × environment interactions were identified for all phenology and yield traits analysed. Principal component analysis of population structure evidenced European domestication bottlenecks, visualized by clustering of breeding materials and cultivars. GWAS provided contribution towards deciphering vernalization pathway in legumes, and, apart from highlighting known domestication loci (Ku/Julius and mol), designated novel candidate genes for L. angustifolius traits. Early phenology was associated with genes from vernalization, cold-responsiveness and phosphatidylinositol signalling pathways whereas high yield with genes controlling photosynthesis performance and abiotic stress (drought or heat) tolerance. PCR-based toolbox was developed and validated to enable tracking desired alleles in marker-assisted selection. Narrow-leafed lupin was genotyped with an innovative method of transcriptome profiling and phenotyped for phenology, growth and yield traits in field. Early phenology was found associated with genes from cold-response, vernalization and phosphatidylinositol signalling pathways, whereas high yield with genes running photosystem II and drought or heat stress response. Key loci were supplied with PCR-based toolbox for marker-assisted selection.

A high-density consensus linkage map of white lupin highlights synteny with narrow-leafed lupin and provides markers tagging key agronomic traits.

White lupin (Lupinus albus L.) is a valuable source of seed protein, carbohydrates and oil, but requires genetic improvement to attain its agronomic potential. This study aimed to (i) develop a new high-density consensus linkage map based on new, transcriptome-anchored markers; (ii) map four important agronomic traits, namely, vernalization requirement, seed alkaloid content, and resistance to anthracnose and Phomopsis stem blight; and, (iii) define regions of synteny between the L. albus and narrow-leafed lupin (L. angustifolius L.) genomes. Mapping of white lupin quantitative trait loci (QTLs) revealed polygenic control of vernalization responsiveness and anthracnose resistance, as well as a single locus regulating seed alkaloid content. We found high sequence collinearity between white and narrow-leafed lupin genomes. Interestingly, the white lupin QTLs did not correspond to previously mapped narrow-leafed lupin loci conferring vernalization independence, anthracnose resistance, low alkaloids and Phomopsis stem blight resistance, highlighting different genetic control of these traits. Our suite of allele-sequenced and PCR validated markers tagging these QTLs is immediately applicable for marker-assisted selection in white lupin breeding. The consensus map constitutes a platform for synteny-based gene cloning approaches and can support the forthcoming white lupin genome sequencing efforts.

Nitrate simultaneously enhances lipid and protein accumulation in developing yellow lupin cotyledons cultured in vitro, but not under field conditions.

The research was conducted on yellow lupin (Lupinus luteus L.) mature seeds, developing cotyledons, developing pods, and seedlings. The main storage compound in yellow lupin seeds is protein, whose content may reach up to 45%. Oil content in seeds of yellow lupin is about 6%. In such protein-storing seeds there is a strong negative relationship between accumulation of storage lipid and protein. An increase in protein content causes a decrease in lipid level, and vice versa. However, simultaneous increase in lipid and protein content is possible in developing lupin cotyledons (the main storage organs of lupin seeds) cultured in vitro. Such an effect was obtained by feeding the cotyledons with nitrate (35mM). The same positive relationship in storage lipid and protein accumulation was also obtained in developing lupin pods fed with nitrate (35mM), detached from the mother plant, and maintained under quasi in vitro conditions. Fertilization of lupin plants with nitrate under field conditions (40 or 80kgNha-1 applied before sowing, at the nodulation stage or at the flowering and pod formation stage) did not cause significant changes in lipid and protein contents in mature seeds. Experiments performed on lupin seedlings cultivated hydroponically showed that nitrate added to the medium was accumulated mainly in roots, and at a remarkably lower level in shoots. We hypothesize that the lack of stimulatory effect of nitrate on storage lipid and protein accumulation in seeds under field conditions is due to inefficient transport of nitrate from the root to developing pods in lupin plants. This causes that the level of nitrate inside the developing lupin seeds is not elevated under field conditions.

Diversity of selected Lupinus angustifolius L. genotypes at the phenotypic and DNA level with respect to microscopic seed coat structure and thickness.

The paper investigates seed coat characteristics (as a percentage of overall seed diameter) in Lupinus angustifolius L., a potential forage crop. In the study ten L. angustifolius genotypes, including three Polish cultivars, two Australian cultivars, three mutants originated from cv. 'Emir', and one Belarusian and one Australian breeding line were evaluated. The highest seed coat percentage was recorded in cultivars 'Sonet' and 'Emir'. The lowest seed coat thickness percentage (below 20%) was noted for breeding lines 11257-19, LAG24 and cultivar 'Zeus' (17.87%, 18.91% 19.60%, respectively). Despite having low seed weight, the Australian line no. 11257-19 was characterized by a desirable proportion of seed coat to the weight of seeds. In general, estimation of the correlation coefficient indicated a tendency that larger seeds had thinner coats. Scanning Electron Microscopy images showed low variation of seed coat sculpture and the top of seeds covered with a cuticle. Most of the studied genotypes were characterized by a cristatepapillate seed coat surface, formed by elongated polygonal cells. Only breeding line no. 11267-19 had a different shape of the cells building the surface layer of the coat. In order to illustrate genetic diversity among the genotypes tested, 24 ISSR primers were used. They generated a total of 161 polymorphic amplification products in 10 evaluated narrow-leaved lupin genotypes.