Soybean is one of the chief crops producing protein and oil for human consumption. Wild soybean, the ancestor of cultivated soybean, possesses high seed protein content; therefore, it is a valuable genetic resource that could enhance protein content in the cultivated varieties. To identify the genes responsible for increasing protein content in wild soybean, a population comprising 113 BC4F6 chromosome segment substitution lines (CSSL) was developed from a cross between soybean cultivar ‘Jackson’ and wild soybean accession JWS156-1. The CSSL population was cultivated in the field conditions for 3 years (2018, 2019 and 2020), and the seeds harvested from each line were analysed for protein and oil contents by InfraTec Nova instrument. Quantitative trait locus (QTL) analysis with 243 SSR markers identified 12 QTLs associated with seed protein, oil and protein + oil contents. Among these QTLs, qPro8 and qPro19, two major and stable QTLs for protein content, were detected on chromosomes 8 and 19, respectively. No QTL for oil content was detected in the vicinity of qPro19, indicating that qPro19 did not influence the seed oil content. The effect of qPro19 was validated using near-isogenic lines (NILs) of qPro19. By introducing the qPro19 allele from wild soybean into another soybean variety, ‘Tachiyutaka’, a BC4 line, T-678, that showed enhanced seed protein content, without reducing the seed oil content. This study implied that the qPro19 allele from wild soybean could be a potential genetic resource for breeding programmes aimed to improve soybean seed quality.

The aim of this study was to establish associations of kernel weight and colour with ecogeographic factors and molecular markers, based on ten wild barley [Hordeum spontaneum (C. Koch) Thell.] populations sampled in Israel across a southward transect of increasing aridity. Kernel weight and colour category were scored using barley kernels (naked caryopsis). Small kernel sizes (0.011 g kernel–1) and dark kernels were found in xeric populations. A higher variation of kernel weight was observed in xeric populations. A higher proportion of variation occurred within, rather than among, populations. Water, temperature and soil factors were associated with kernel size variation. Among 18 simple sequence repeats (SSRs) investigated, HVM14, HVM36, HVM43, BMS64 and BMS90 were associated with kernel weight, and HVM68 with kernel colour. The results indicated that high phenotypic variation and genetic diversity are related to ecological stress, and that the association of phenotypic traits with molecular markers, based on natural plant populations, should be interpreted cautiously due to the high chance of spurious associations between traits and molecular markers.

The use of genetics in plant biology aims at the physiological and molecular genetical characterization of the phenotypic variation for the trait under study. Efficient mutant and gene isolation procedures have been developed for a number of plant models such as Arabidopsis thaliana. For this, the map position of the genes and insertion mutagenesis are used. The latter also allows the characterization of genes that are not easily recognized in mutant approaches, by using enhancer or gene-trapping procedures and reverse genetics. In addition to mutants, natural variation present among wild and cultivated varieties of a species provides an important source of genetic variation. The use of molecular markers, advanced mapping populations and specific cytogenetic stocks in case of polyploids, enables a detailed characterization of such natural variation even when it is of a quantitative and polygenic nature. Examples of the various genetic approaches are given.