Dataset Information

Unraveling the Hexaploid Sweetpotato Inheritance Using Ultra-Dense Multilocus Mapping.

ABSTRACT: The hexaploid sweetpotato (Ipomoea batatas (L.) Lam., 2n = 6x = 90) is an important staple food crop worldwide and plays a vital role in alleviating famine in developing countries. Due to its high ploidy level, genetic studies in sweetpotato lag behind major diploid crops significantly. We built an ultra-dense multilocus integrated genetic map and characterized the inheritance system in a sweetpotato full-sib family using our newly developed software, MAPpoly. The resulting genetic map revealed 96.5% collinearity between I. batatas and its diploid relative I. trifida We computed the genotypic probabilities across the whole genome for all individuals in the mapping population and inferred their complete hexaploid haplotypes. We provide evidence that most of the meiotic configurations (73.3%) were resolved in bivalents, although a small portion of multivalent signatures (15.7%), among other inconclusive configurations (11.0%), were also observed. Except for low levels of preferential pairing in linkage group 2, we observed a hexasomic inheritance mechanism in all linkage groups. We propose that the hexasomic-bivalent inheritance promotes stability to the allelic transmission in sweetpotato.

SUBMITTER: Mollinari M

PROVIDER: S-EPMC6945028 | biostudies-literature | 2020 Jan

REPOSITORIES: biostudies-literature

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Unraveling the Hexaploid Sweetpotato Inheritance Using Ultra-Dense Multilocus Mapping.

Mollinari Marcelo M Olukolu Bode A BA Pereira Guilherme da S GDS Khan Awais A Gemenet Dorcus D Yencho G Craig GC Zeng Zhao-Bang ZB

G3 (Bethesda, Md.) 20200107 1

The hexaploid sweetpotato (<i>Ipomoea batatas</i> (L.) Lam., 2n = 6x = 90) is an important staple food crop worldwide and plays a vital role in alleviating famine in developing countries. Due to its high ploidy level, genetic studies in sweetpotato lag behind major diploid crops significantly. We built an ultra-dense multilocus integrated genetic map and characterized the inheritance system in a sweetpotato full-sib family using our newly developed software, MAPpoly. The resulting genetic map re ...[more]

PMID: 31732504

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Project description:The southern root-knot nematode (SRKN; Meloidogyne incognita) is a typical parasitic nematode that affects sweetpotato [Ipomoea batatas (L.) Lam.], causing a significant decrease in crop yield and commercial value. In Japan, the SRKN is classified into 10 races: SP1-SP5, SP6-1, SP6-2, and SP7-SP9, with the dominant race differing according to the cultivation area. Soil insecticides have previously been used to reduce the soil density of SRKNs; however, this practice is both costly and labor intensive. Therefore, the development of SRKN-resistant sweetpotato lines and cultivars is necessary. However, due to the complexity of polyploid inheritance and the highly heterogeneous genomic composition of sweetpotato, genetic information and research for this species are significantly lacking compared to those for other major diploid crop species. In this study, we utilized the recently developed genome-wide association approach, which uses multiple-dose markers to assess autopolyploid species. We performed an association analysis to investigate resistance toward SRKN-SP2, which is the major race in areas with high sweetpotato production in Japan. The segregation ratio of resistant and susceptible lines in the F1 mapping population derived from the resistant "J-Red" and susceptible "Choshu" cultivars was fitted to 1: 3, suggesting that resistance to SP2 may be regulated by two loci present in the simplex. By aligning the double digest restriction-site associated DNA sequencing reads to the published Ipomoea trifida reference sequence, 46,982 single nucleotide polymorphisms (SNPs) were identified (sequencing depth > 200). The association study yielded its highest peak on chromosome 7 (Chr07) and second highest peak on chromosome 3 (Chr03), presenting as a single-dose in both loci. Selective DNA markers were developed to screen for resistant plants using the SNPs identified on Chr03 and Chr07. Our results showed that SRKN-SP2-resistant plants were selected with a probability of approximately 70% when combining the two selective DNA markers. This study serves as a model for the identification of genomic regions that control agricultural traits and the elucidation of their effects, and is expected to greatly advance marker-assisted breeding and association studies in polyploid crop species.

Project description:BACKGROUND:Purple-fleshed sweetpotato (PFSP) is one of the most important crops in the word which helps to bridge the food gap and contribute to solve the malnutrition problem especially in developing countries. Salt stress is seriously limiting its production and distribution. Due to lacking of reference genome, transcriptome sequencing is offering a rapid approach for crop improvement with promising agronomic traits and stress adaptability. RESULTS:Five cDNA libraries were prepared from the third true leaf of hexaploid sweetpotato at seedlings stage (Xuzi-8 cultivar) treated with 200?mM NaCl for 0, 1, 6, 12, 48?h. Using second and third generation technology, Illumina sequencing generated 170,344,392 clean high-quality long reads that were assembled into 15,998 unigenes with an average length 2178 base pair and 96.55% of these unigenes were functionally annotated in the NR protein database. A number of 537 unigenes failed to hit any homologs which may be considered as novel genes. The current results indicated that sweetpotato plants behavior during the first hour of salt stress was different than the other three time points. Furthermore, expression profiling analysis identified 4, 479, 281, 508 significantly expressed unigenes in salt stress treated samples at the different time points including 1, 6, 12, 48?h, respectively as compared to control. In addition, there were 4, 1202, 764 and 2195 transcription factors differentially regulated DEGs by salt stress at different time points including 1, 6, 12, 48?h of salt stress. Validation experiment was done using 6 randomly selected unigenes and the results was in agree with the DEG results. Protein kinases include many genes which were found to play a vital role in phosphorylation process and act as a signal transductor/ receptor proteins in membranes. These findings suggest that salt stress tolerance in hexaploid sweetpotato plants may be mainly affected by TFs, PKs, Protein Detox and hormones related genes which contribute to enhance salt tolerance. CONCLUSION:These transcriptome sequencing data of hexaploid sweetpotato under salt stress conditions can provide a valuable resource for sweetpotato breeding research and focus on novel insights into hexaploid sweetpotato responses to salt stress. In addition, it offers new candidate genes or markers that can be used as a guide to the future studies attempting to breed salt tolerance sweetpotato cultivars.

Dataset Information

Unraveling the Hexaploid Sweetpotato Inheritance Using Ultra-Dense Multilocus Mapping.

Publications

Unraveling the Hexaploid Sweetpotato Inheritance Using Ultra-Dense Multilocus Mapping.

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