Biology subjects

Schulman, A. H.

Publications and source records attributed to Schulman, A. H..

8 recordsLinked to original sources

bioRxiv2026

VC1 and the production of vicine and convicine in the genus Vicia

Many Vicia species contain vicine and convicine (VC), which limit the use of faba bean and some vetches in food and feed. The first step in VC biosynthesis in V. faba is shared with the riboflavin pathway and attributed to VC1, a member of the ribAB family. Since riboflavin is ubiquitous to life, we examined the distribution of VC production in genus Vicia. Three accessions of each of 33 Vicia species were grown in glasshouse conditions to provide fresh seeds for VC analysis and leaves for DNA analysis. PCR was used to amplify fragments of the VC1/ribAB gene for sequencing, and these sequences were used to create a phylogenetic tree. COX1 and ITS2 sequences were used for examining the nucleotide diversity in the subgenera. VC and DNA sequences consistent with VC1 were found only in members of subgenus Vicia. In V. lathyroides, VC1 was present but no VC was detected. There was less sequence diversity in VC1/ribAB sequences of subgenus Cracca than in those of subgenus Vicia, suggesting that ribAB remained under stricter purifying selection than VC1. VC1 is confirmed as a prerequisite for the presence of VC, and the gene and its products are restricted to subgenus Vicia. HighlightThe favism-causing factors of vetches and faba bean, vicine and convicine, depend on the presence of the VC1 variant of the ribAB gene, which is found in only one subgenus.

plant biology↗

bioRxiv2024

New loci and candidate genes in spring two-rowed barley detected through meta-analysis of a field trial European network

This study contributes new knowledge on quantitative trait loci (QTLs) and candidate genes for adaptive traits and yield in two-rowed spring barley. A meta-analysis of a network of field trials, varying in latitude and sowing date, with 151 cultivars across several European countries, increased QTL detection power compared to single-trial analyses. The traits analysed were heading date (HD), plant height (PH), thousand-grain weight (TGW), and grain yield (GY). Breaking down the analysis by the main genotype-by-environment trends revealed QTLs and candidate genes specific to conditions like sowing date and latitude. A historical look on the evolution of QTL frequencies revealed that early selection focused on PH and TGW, likely due to their high heritability. GY selection occurred later, facilitated by reduced variance in other traits. The study observed that favourable alleles for plant height were often fixed before those for grain yield and TGW. Some regions showed linkage in repulsion, suggesting targets for future breeding. Several candidate genes were identified, including known genes and new candidates based on orthology with rice. Remarkably, the deficiens allele of gene Vrs1, appears associated to higher GY. These findings provide valuable insights for barley breeders aiming to improve yield, and other agronomic traits. HighlightA dense genome-wide meta-analysis provides new QTLs, reveals breeding history trends and identifies new candidate genes for yield, plant height, grain weight and heading time of spring barley.

genetics↗

bioRxiv2024

Precision phenotyping of a barley diversity set reveals distinct drought response strategies

Plants exhibit a wide array of responses and adaptive mechanisms to drought. During drought, the trade-off between water loss and CO2 uptake for growth is mediated by the regulation of stomatal aperture in response to soil water content (SWC), among other factors. We earlier identified, in a few reference varieties of barley that differed by the SWC at which transpiration was curtailed, two divergent water use strategies: water-saving ("isohydric") and water-spending ("anisohydric"). We proposed that an isohydric strategy may reduce risk from early droughts in climates where the probability of precipitation increases during the growing season, whereas an anisohydric strategy is consistent with environments having terminal droughts, or with those where dry periods are short and show little seasonal variation. Here, we have examined drought response in an 81-line barley diversity set that spans 20th century European barley breeding and identified a several lines with a third, dynamic transpirational response to drought. We found a strong positive correlation between vigor and transpiration, the dynamic group being highest for both. However, these lines curtailed daily transpiration at a higher SWC than the isohydric group. While the dynamic lines, particularly cv Hydrogen and Baronesse, were not the most resilient in terms of restoring initial growth rates, their strong initial vigor and high return to initial transpiration rates meant that their growth nevertheless surpassed more resilient lines during recovery from drought. The results will be of use for defining barley physiological ideotypes suited to future climate scenarios.

plant biology↗

bioRxiv2023

Drought and recovery in barley: key gene networks and retrotransposon response.

O_LIDuring drought, plants close their stomata at a critical soil water content (SWC), together with diverse physiological, developmental, and biochemical responses. C_LIO_LIUsing precision-phenotyping lysimeters, we imposed pre-flowering drought on four barley varieties (Arvo, Golden Promise, Hankkija 673 and Morex) and followed their physiological responses. For Golden Promise, we carried out RNA-seq on leaf transcripts before and during drought, and during recovery, also examining retrotransposon BARE1 expression. Transcriptional data were subjected to network analysis. C_LIO_LIThe varieties differed by their critical SWC, Hankkija 673 responding at the highest and Golden Promise at the lowest. Pathways connected to drought and salinity response were strongly upregulated during drought; pathways connected to growth and development were strongly downregulated. During recovery, growth and development pathways were upregulated; altogether 117 networked genes involved in ubiquitin-mediated autophagy were downregulated. The differential response to SWC suggests adaptation to distinct rainfall patterns. C_LIO_LIWe identified several strongly differentially expressed genes not earlier associated with drought response in barley. BARE1 transcription is strongly transcriptionally upregulated by drought and downregulated during recovery unequally between the investigated cultivars. The downregulation of networked autophagy genes suggests a role for autophagy in drought response; its importance to resilience should be further investigated. C_LI

plant biology↗

bioRxiv2022

Multi-environment genome-wide association mapping of culm morphology traits in barley

In cereals with hollow internodes, lodging resistance is influenced by morphological characteristics such as internode diameter and culm wall thickness. Despite their relevance, knowledge of the genetic control of these traits and their relationship with lodging is lacking in temperate cereals such as barley. To fill this gap, we developed an image-analysis based protocol to accurately phenotype culm diameter and culm wall thickness across 261 barley accessions. Analysis of culm trait data collected from field trials in 7 different environments revealed genetic control as supported by high heritability values, as well as genotype-by-environment interactions. The collection was structured mainly according to row-type, which had a confounding effect on culm traits as evidenced by phenotypic correlations. In addition, culm traits showed strong negative correlations with lodging but weak correlations with plant height across row-types, indicating the possibility of improving lodging resistance independent of plant height. Using 50k iSelect SNP genotyping data, we conducted multi-environment genome-wide association studies using mixed model approach across the whole panel and row-type subsets: we identified a total of 192 QTLs for the studied traits, including subpopulation-specific QTLs and several main effect loci for culm traits showing negative effects on lodging without impacting plant height. Providing first insights into the genetic architecture of culm morphology in barley and the possible role of candidate genes involved in hormone and cell wall related pathways, this work supports the potential of loci underpinning culm features to improve lodging resistance and increase barley yield stability under changing environments. One-sentence summaryGenetic analysis of a diverse collection of European barleys reveals genomic regions underpinning stem morphological features associated with lodging resistance.

plant biology↗

bioRxiv2021

Genomic regions associated with chocolate spot (Botrytis fabae Sard.) resistance in fababean (Vicia faba L.)

Chocolate spot (CS), caused by Botrytis fabae Sard., is an important threat to global faba bean production. Growing resistant faba bean cultivars is, therefore, paramount to preventing yield loss. To date, there have been no reported quantitative trait loci (QTLs) associated with CS resistance in faba bean. The objective of this study was to identify genomic regions associated with CS resistance using a recombinant inbred line (RIL) population derived from resistant accession ILB 938. A total of 165 RILs from the cross Melodie/2 x ILB 938/2 were genotyped and evaluated for CS reactions under replicated controlled climate conditions. QTL analysis identified five loci contributing to CS resistance on faba bean chromosomes 1 and 6, accounting for 5.0-23.4% of the total phenotypic variance. The sequences of SNP markers linked to resistance QTLs on chromosome 1 that have the largest effects encode multiple classes of putative disease and/or defense-related genes. The results of this study not only provide insight into disease-resistance QTLs, but also can be used as potential targets for marker-assisted breeding in faba bean genetic improvement for CS resistance. Key messageQTL mapping identified key genomic regions associated with chocolate spot resistance on faba bean chromosomes 1 and 6, which may serve as novel genetic tools to develop disease-resistant faba bean cultivars.

genomics↗

bioRxiv2020

VC1 catalyzes a key step in the biosynthesis of vicine from GTP in faba bean

Faba bean is a widely adapted and high-yielding legume cultivated for its protein-rich seeds1. However, the seeds accumulate the anti-nutritional pyrimidine glucosides vicine and convicine, which can cause haemolytic anaemia--favism--in the 400 million individuals genetically predisposed by a deficiency in glucose-6-phosphate dehydrogenase2. Here, we identify the first enzyme associated with vicine and convicine biosynthesis, which we name VC1. We show that VC1 co-locates with the major QTL for vicine and convicine content and that the expression of VC1 correlates highly with vicine content across tissues. We also show that low-vicine varieties express a version of VC1 carrying a small, frame-shift insertion, and that overexpression of wild-type VC1 leads to an increase in vicine levels. VC1 encodes a functional GTP cyclohydrolase II, an enzyme normally involved in riboflavin biosynthesis from the purine GTP. Through feeding studies, we demonstrate that GTP is a precursor of vicine both in faba bean and in the distantly related plant bitter gourd. Our results reveal an unexpected biosynthetic origin for vicine and convicine and pave the way for the development of faba bean cultivars that are free from these anti-nutrients, providing a safe and sustainable source of dietary protein.

biochemistry↗

bioRxiv2019

The genome of cowpea (Vigna unguiculata Walp.)

Cowpea (Vigna unguiculata [L.] Walp.) is a major crop for worldwide food and nutritional security, especially in sub-Saharan Africa, that is resilient to hot and drought-prone environments. A high-quality assembly of the single-haplotype inbred genome of cowpea IT97K-499-35 was developed by exploiting the synergies between single molecule real-time sequencing, optical and genetic mapping, and a novel assembly reconciliation algorithm. A total of 519 Mb is included in the assembled sequences. Nearly half of the assembled sequence is composed of repetitive elements, which are enriched within recombination-poor pericentromeric regions. A comparative analysis of these elements suggests that genome size differences between Vigna species are mainly attributable to changes in the amount of Gypsy retrotransposons. Conversely, genes are more abundant in more distal, high-recombination regions of the chromosomes; there appears to be more duplication of genes within the NBS-LRR and the SAUR-like auxin superfamilies compared to other warm-season legumes that have been sequenced. A surprising outcome of this study is the identification of a chromosomal inversion of 4.2 Mb among landraces and cultivars, which includes a gene that has been associated in other plants with interactions with the parasitic weed Striga gesnerioides. The genome sequence also facilitated the identification of a putative syntelog for multiple organ gigantism in legumes. A new numbering system has been adopted for cowpea chromosomes based on synteny with common bean (Phaseolus vulgaris).

genomics↗