New tools to screen wild peanut species for aflatoxin accumulation and genetic fingerprinting

Abstract

BackgroundAflatoxin contamination in peanut seeds is still a serious problem for the industry and human health. No stable aflatoxin resistant cultivars have yet been produced, and given the narrow genetic background of cultivated peanuts, wild species became an important source of genetic diversity. Wild peanut seeds, however, are not abundant, thus, an effective method of screening for aflatoxin accumulation using minimal seeds is highly desirable. In addition, keeping record of genetic fingerprinting of each accession would be very useful for breeding programs and for the identification of accessions within germplasm collections.ResultsIn this study, we report a method of screening for aflatoxin accumulation that is applicable to the small-size seeds of wild peanuts, increases the reliability by testing seed viability, and records the genetic fingerprinting of the samples. Aflatoxin levels observed among 20 wild peanut species varied from zero to 19000 ng.g-1 and 155 ng.g-1 of aflatoxin B1 and B2, respectively. We report the screening of 373 molecular markers, including 288 novel SSRs, tested on 20 wild peanut species. Multivariate analysis by Neighbor-Joining, Principal Component Analysis and 3D-Principal Coordinate Analysis using 134 (36 %) transferable markers, in general grouped the samples according to their reported genomes. The best 88 markers, those with high fluorescence, good scorability and transferability, are reported with BLAST results. High quality markers (total 98) that discriminated genomes are reported. A high quality marker with UPIC score 16 (16 out of 20 species discriminated) had significant hits on BLAST2GO to a pentatricopeptide-repeat protein, another marker with score 5 had hits on UDP-D-apiose synthase, and a third one with score 12 had BLASTn hits on La-RP 1B protein. Together, these three markers discriminated all 20 species tested.ConclusionsThis study provides a reliable method to screen wild species of peanut for aflatoxin resistance using minimal seeds. In addition we report 288 new SSRs for peanut, and a cost-effective combination of markers sufficient to discriminate all 20 species tested. These tools can be used for the systematic search of aflatoxin resistant germplasm keeping record of the genetic fingerprinting of the accessions tested for breeding purpose.Electronic supplementary materialThe online version of this article (10.1186/s12870-018-1355-9) contains supplementary material, which is available to authorized users.

Introgression of peanut smut resistance from landraces to elite peanut cultivars (Arachis hypogaea L.)

“…Factors such as small population size, segregation distortion, and/or SSR/InDel marker ascertainment bias might explain the relatively low number of PSA from the resistant parent (I0349) observed in crosses JS34212 (II) and JS35112 (III). Overall similar level of transferability, 36% (134 out of 373) was observed when the set of SSR/InDel markers used here was tested on 20 wild peanut species of section Arachis, Erectoides, Heteranthae, Procumbentes and Rhizomatosae [31]. Parent specific alleles (PSA) from microsatellites have been used to demonstrate introgression in crosses between Triticum aestivum × Aegilops speltoides [54].…”

“…The parents of the three populations were screened with 376 molecular markers: 288 SSRs [31], 12 insertion/deletion (InDel) markers [32], and 73 SSRs obtained from the literature for peanut and related species [14, 33–37]. The complete list of 376 primer sets was previously reported (Arias et al, 2018).…”

Genotyping tools and resources to assess peanut germplasm: smut-resistant landraces as a case study

“…The latter emphasizes the need of an efficient and cost-effective genotyping system for detecting within-accession variation in the U.S. peanut germplasm collection. While genebanks seek to preserve the genetic composition of the original sample, in many cases, such as in peanut landraces, this involves maintaining genetically heterogenous accessions in a way that is difficult to use for gene discovery and crop breeding ( Arias et al, 2018 ; Barkley et al, 2016 ; McCouch et al, 2012 ).…”

Advances in Crop Improvement and Delivery Research for Nutritional Quality and Health Benefits of Groundnut (Arachis hypogaea L.)

“…J 11 and 55-437, released in West Africa are known to accumulate low pre-harvest levels of aflatoxin (Mayeux et al, 2003). However, no aflatoxin resistant varieties have been released yet (Arias et al, 2018;Desmae et al, 2019).…”