Biology subjects

Emrani, N.

Publications and source records attributed to Emrani, N..

6 recordsLinked to original sources

bioRxiv2024

Uncovering Genes Essential in Domestication and Breeding of Sugar Beet

The genus Beta encompasses economically important root crops such as sugar and table beet. A Beta diversity set including the wild relative B. vulgaris ssp. maritima was grown in the field, and a large phenotypic diversity was observed. The genomes of 290 accessions were sequenced, and more than 10 million high-quality SNPs were employed to study genetic diversity. A genome-wide association study was performed, and marker-trait associations were found for nine phenotypic traits. The candidate gene within the M locus controlling monogermity on chromosome 4 was previously unknown. The most significant association for monogermity was identified at the end of chromosome 4. Within this region, a non-synonymous mutation within the Zinc-Finger domain of the WIP2 gene co-segregated with monogermity. This gene plays a regulatory role in AGL8/FUL in Arabidopsis. Intriguingly, commercial hybrids are in a heterozygous state at this position. Thus, the long-sought gene for monogermity was identified in this study. Red and yellow pigmentation due to betalain accumulation in shoots and roots is an important characteristic of table and leaf beets. The strongest associations were found upstream or downstream of two genes encoding Cytochrome P450 and anthocyanin MYB-like transcription factor proteins involved in betalain biosynthesis. Significant associations for Cercospora leaf spot resistance were identified on chromosomes 1, 2, 7, and 9. The associated regions harbor genes encoding proteins with leucine-rich repeats and nucleotide binding sites whose homologs are major constituents of plant-pathogen defense.

genomics↗

bioRxiv2024

Signatures in domesticated beet genomes pointing at genes under selection in a sucrose-storing root crop

The genus Beta encompasses important crops such as sugar, table, fodder, and leaf beets. All cultivated beets are believed to have originated from the wild sea beet, B. vulgaris subsp. maritima. Sugar beet, a recent crop dating back nearly 200 years, was selectively bred for enhanced root yield in combination with high sucrose content. We assembled a Beta diversity panel comprising wild and cultivated beet accessions. Whole-genome sequencing identified 10.3 million SNP markers. Four distinct genetic clusters were identified: table beet, sugar beet, Mediterranean sea beet, and Atlantic sea beet. A phylogenetic analysis revealed that cultivated beet accessions were genetically closer to Mediterranean than to Atlantic sea beet and that cultivated beets producing storage roots share a common ancestor. Cultivated beets exhibited genome regions with reduced nucleotide diversity compared to Mediterranean sea beets, indicating selection signatures. These regions contained putative candidate genes with potential roles in root development, suppression of lateral root formation, flowering time, and sucrose metabolism. A yet unknown sucrose transporter on chromosome 6 showed reduced nucleotide diversity exclusively in sugar beet accessions compared to other Beta types with low sucrose content, suggesting its role in sucrose storage. Within a region of high nucleotide diversity between accessions with contrasting root phenotypes, we found two genes encoding auxin response factors, which play a crucial role in root development. We reason these genes to be significant root thickening regulators in root crops.

genomics↗

bioRxiv2023

Leaf and shoot apical meristem transcriptomes of quinoa (Chenopodium quinoa Willd.) in response to photoperiod and plant development

Our study aimed to identify candidate genes for flowering time regulation and photoperiod response in quinoa. We investigated the timing of photoperiod-driven floral transition and analyzed the transcriptomes of leaf and shoot apical meristems in photoperiod-sensitive and -insensitive quinoa accessions. Histology analysis of the apical meristem showed that floral transition in quinoa initiates two to three weeks after sowing. We found four groups of differentially expressed genes responding to plant development and floral transition, which were annotated in the QQ74-V2 reference genome, including (i) 222 genes differentially responding to photoperiod in leaves, (ii) 1,812 genes differentially expressed between accessions under long-day conditions in leaves, (iii) 57 genes responding to developmental changes between weeks under short-day conditions in leaves, and (iv) 911 genes responding to floral transition within the shoot apical meristem. Interestingly, out of the thousands of candidates, two putative FT orthologues and several others have been reported as key regulators of flowering time in other species (e.g., SOC1, COL, AP1). Additionally, we used co-expression networks to associate novel transcripts to a putative biological process based on the annotated genes within the same co-expression cluster. The candidate genes in this study would benefit quinoa breeding by identifying and integrating their beneficial haplotypes in crossing programs to develop adapted cultivars to diverse environmental conditions.

plant biology↗

bioRxiv2022

High-density mapping of QTL controlling agronomically important traits in quinoa (Chenopodium quinoa Willd.)

Quinoa is a pseudocereal originating from the Andean regions. In spite of quinoas long cultivation history, genetic analysis of this crop is still in its infancy. We aimed to localize QTL contributing to the phenotypic variation of agronomically important traits. We crossed the Chilean accession PI-614889 and the Peruvian accession CHEN-109, which depicted significant differences in days to flowering, days to maturity, plant height, panicle length, thousand kernel weight (TKW), saponin content, and mildew susceptibility. We observed sizeable phenotypic variation across F2 plants and F3 families grown in the greenhouse and in the field, respectively. We used Skim-seq to genotype the F2 population and constructed a high-density genetic map with 133,923 SNPs. Fifteen QTL were found for ten traits. Two significant QTL, common in F2 and F3 generations, depicted pleiotropy for days to flowering, plant height, and TKW. The pleiotropic QTL harbored several putative candidate genes involved in photoperiod response and flowering time regulation. This study presents the first high-density genetic map of quinoa that incorporates QTL for several important agronomical traits. The pleiotropic loci can facilitate marker assisted selection in quinoa breeding programs. Key messageSkim-sequencing enabled the construction a high-density genetic map (133,923 SNPs) and fifteen QTL were detected for ten agronomically important traits.

genetics↗

bioRxiv2020

Genome-wide association study in the pseudocereal quinoa reveals selection pattern typical for crops with a short breeding history

Quinoa germplasm preserves useful and substantial genetic variation, yet it remains untapped due to a lack of implementation of modern breeding tools. We have integrated field and sequence data to characterize a large diversity panel of quinoa. Whole-genome sequencing of 310 accessions revealed 2.9 million polymorphic high confidence SNP loci. Highland and Lowland quinoa were clustered into two main groups, with FST divergence of 0.36 and fast LD decay of 6.5 and 49.8 Kb, respectively. A genome-wide association study uncovered 600 SNPs stably associated with 17 agronomic traits. Two candidate genes are associated with thousand seed weight, and a resistance gene analog is associated with downy mildew resistance. We also identified pleiotropically acting loci for four agronomic traits that are highly responding to photoperiod hence important for the adaptation to different environments. This work demonstrates the use of re-sequencing data of an orphan crop, which is partially domesticated to rapidly identify marker-trait association and provides the underpinning elements for genomics-enabled quinoa breeding.

genomics↗

bioRxiv2020

Validation of suitable genes for normalization of diurnal gene expression studies in Chenopodium quinoa

Quinoa depicts high nutritional quality and abiotic stress resistance attracting strong interest in the last years. To unravel the function of candidate genes for agronomically relevant traits, studying their transcriptional activities by RT-qPCR is an important experimental approach. The accuracy of such experiments strongly depends on precise data normalization. To date, validation of potential candidate genes for normalization of diurnal expression studies has not been performed in C. quinoa. We selected eight candidate genes based on transcriptome data and literature survey, including conventionally used reference genes. We used three statistical algorithms (BestKeeper, geNorm and NormFinder) to test their stability and added further validation by a simulation-based strategy. We demonstrated that using different reference genes, including those top ranked by stability, causes significant differences among the resulting diurnal expression patterns, and that our novel approach overcomes failures related to stability-based selection of reference genes. Our results show that isocitrate dehydrogenase enzyme (IDH-A) and polypyrimidine tract-binding protein (PTB) are suitable genes to normalize diurnal expression data of two different quinoa accessions. The validated reference genes obtained in this study will improve the accuracy of RT-qPCR data normalization and facilitate gene expression studies in quinoa.

plant biology↗