The H^(+)-pyrophosphatase IbVP1 regulates carbon flux to influence the starch metabolism and yield of sweet potato

Storage roots of sweet potato are important sink organs for photoassimilates and energy,and carbohydrate metabolism in storage roots affects yield and starch production.Our previous study showed that sweet potato H+-pyrophosphatase(IbVP1)plays a vital role in mitigating iron deficiency and positively controls fibrous root growth.However,its roles in regulating starch production in storage roots have not been investigated.In this study,we found that IbVP1 overexpression in sweet potato improved the photosynthesis ability of and sucrose content in source leaves and increased both the starch content in and total yield of sink tissues.Using 13C-labeled sucrose feeding,we determined that IbVP1 overexpression promotes phloem loading and sucrose long-distance transport and enhances Pi-use efficiency.In sweet potato plants overexpressing IbVP1,the expression levels of starch biosynthesis pathway genes,especially AGPase and GBSSI,were upregulated,leading to changes in the structure,composition,and physicochemical properties of stored starch.Our study shows that the IbVP1 gene plays an important role in regulating starch metabolism in sweet potato.Application of the VP1 gene in genetic engineering of sweet potato cultivars may allow the improvement of starch production and yield under stress or nutrient-limited conditions.

Haplotype-based phylogenetic analysis and population genomics uncover the origin and domestication of sweetpotato

The hexaploid sweetpotato(lpomoea batatas)is one of the most important root crops worldwide.However,its genetic origin remains controversial,and its domestication history remains unknown.In this study,we used a range of genetic evidence and a newly developed haplotype-based phylogenetic analysis to identify two probable progenitors of sweetpotato.The diploid progenitor was likely closely related to lpomoea ae-quatoriensis and contributed the B,subgenome,IbT-DNA2,and the lineage 1 type of chloroplast genome to sweetpotato.The tetraploid progenitor of sweetpotato was most likely l.batatas 4x,which donated the B2 subgenome,IbT-DNA1,and the lineage 2 type of chloroplast genome.Sweetpotato most likely originated from reciprocal crosses between the diploid and tetraploid progenitors,followed by a subsequent whole-genome duplication.In addition,we detected biased gene exchanges between the subgenomes;the rate of B,to B2 subgenome conversions was nearly three times higher than that of B2 to B subgenome conver-sions.Our analyses revealed that genes involved in storage root formation,maintenance of genome stabil-ity,biotic resistance,sugar transport,and potassium uptake were selected during the speciation and domestication of sweetpotato.This study sheds light on the evolution of sweetpotato and paves the way forimprovementofthiscrop.

Genome-wide identification of agronomically important genes in outcrossing crops using OutcrossSeq

Many important crops(e.g.,tuber,root,and tree crops)are cross-pollinating.For these crops,no inbred lines are available for genetic study and breeding because they are self-incompatible,clonally propagated,or have a long generation time,making the identification of agronomically important genes difficult,particularly in crops with a complex autopolyploid genome.In this study,we developed a method,OutcrossSeq,for mapping agronomically important loci in outcrossing crops based on whole-genome low-coverage resequencing of a large genetic population,and designed three computation algorithms in OutcrossSeq for different types of outcrossing populations.We applied OutcrossSeq to a tuberous root crop(sweet potato,autopolyploid),a tree crop(walnut tree,highly heterozygous diploid),and hybrid crops(double-cross populations)to generate high-density genotype maps for the outcrossing populations,which enable precise identification of genomic loci underlying important agronomic traits.Candidate causative genes at these loci were detected based on functional clues.Taken together,our results indicate that OutcrossSeq is a robust and powerful method for identifying agronomically important genes in heterozygous species,including polyploids,in a cost-efficient way.The OutcrossSeq software and its instruction manual are available for downloading at www.xhhuanglab.cn/tool/OutcrossSeq.html.