Lathyrus odoratus (sweet pea) is an ornamental plant with exceptional floral scent, previously used as an experimental organism in the early development of Mendelian genetics. However, its terpene ...synthases (TPSs), which act as metabolic gatekeepers in the biosynthesis of volatile terpenoids, remain to be characterized. Auto-Headspace Solid-phase Microextraction/Gas chromatography-mass spectrometry analysis of floral volatile terpene constituents from seven sweet pea cultivars identified α-bergamotene, linalool, (-)-α-cubebene, geraniol, β-caryophyllene and β-sesquiphellandrene as the dominant compounds. RNA sequencing was performed to profile the transcriptome of L. odoratus flowers. Bioinformatic analysis identified eight TPS genes (acronymed as LoTPS) that were successfully cloned, heterologously expressed and functionally analyzed. LoTPS4 and LoTPS7, belonging to the TPS-b clade, biochemically catalyzed the formation of monoterpenes and sesquiterpenes. LoTPS3 and LoTPS8, placed in the TPS-a clade, also generated monoterpenes and sesquiterpenes, while LoTPS12 belonging to the TPS-g clade showed linalool/nerolidol synthase activity. Notably, biochemical assays of the recombinant LoTPS proteins revealed their catalytic promiscuity, and the enzymatic products were basically consistent with major volatile compounds released from sweet pea flowers. The data from our study lay the foundation for the chemical ecology, molecular genetics and biotechnological improvement of sweet pea and other legumes (Fabaceae).
Grass pea (
L.) is an important legume crop grown mainly in South Asia and Sub-Saharan Africa. This underutilized legume can withstand harsh environmental conditions including drought and flooding. ...During drought-induced famines, this protein-rich legume serves as a food source for poor farmers when other crops fail under harsh environmental conditions; however, its use is limited because of the presence of an endogenous neurotoxic nonprotein amino acid β-
-oxalyl-l-α,β-diaminopropionic acid (β-ODAP). Long-term consumption of
and β-ODAP is linked to lathyrism, which is a degenerative motor neuron syndrome. Pharmacological studies indicate that nutritional deficiencies in methionine and cysteine may aggravate the neurotoxicity of β-ODAP. The biosynthetic pathway leading to the production of β-ODAP is poorly understood, but is linked to sulfur metabolism. To date, only a limited number of studies have been conducted in grass pea on the sulfur assimilatory enzymes and how these enzymes regulate the biosynthesis of β-ODAP. Here, we review the current knowledge on the role of sulfur metabolism in grass pea and its contribution to β-ODAP biosynthesis. Unraveling the fundamental steps and regulation of β-ODAP biosynthesis in grass pea will be vital for the development of improved varieties of this underutilized legume.
Tribe Fabeae comprises about 380 legume species, including some of the most ancient and important crops like lentil, pea, and broad bean. Breeding efforts in legume crops rely on a detailed knowledge ...of closest wild relatives and geographic origin. Relationships within the tribe, however, are incompletely known and previous molecular results conflicted with the traditional morphology-based classification. Here we analyse the systematics, biogeography, and character evolution in the tribe based on plastid and nuclear DNA sequences.
Phylogenetic analyses including c. 70% of the species in the tribe show that the genera Vicia and Lathyrus in their current circumscription are not monophyletic: Pisum and Vavilovia are nested in Lathyrus, the genus Lens is nested in Vicia. A small, well-supported clade including Vicia hirsuta, V. sylvatica, and some Mediterranean endemics, is the sister group to all remaining species in the tribe. Fabeae originated in the East Mediterranean region in the Miocene (23-16 million years ago (Ma)) and spread at least 39 times into Eurasia, seven times to the Americas, twice to tropical Africa and four times to Macaronesia. Broad bean (V. faba) and its sister V. paucijuga originated in Asia and might be sister to V. oroboides. Lentil (Lens culinaris ssp. culinaris) is of Mediterranean origin and together with eight very close relatives forms a clade that is nested in the core Vicia, where it evolved c. 14 Ma. The Pisum clade is nested in Lathyrus in a grade with the Mediterranean L. gloeosperma, L. neurolobus, and L. nissolia. The extinct Azorean endemic V. dennesiana belongs in section Cracca and is nested among Mediterranean species. According to our ancestral character state reconstruction results, ancestors of Fabeae had a basic chromosome number of 2n=14, an annual life form, and evenly hairy, dorsiventrally compressed styles.
Fabeae evolved in the Eastern Mediterranean in the middle Miocene and spread from there across Eurasia, into Tropical Africa, and at least seven times to the Americas. The middle-Atlantic islands were colonized four times but apparently did not serve as stepping-stones for Atlantic crossings. Long-distance dispersal events are relatively common in Fabeae (seven per ten million years). Current generic and infrageneric circumscriptions in Fabeae do not reflect monophyletic groups and should be revised. Suggestions for generic level delimitation are offered.
Grass pea (Lathyrus sativus L.) is a rich source of protein cultivated as an insurance crop in Ethiopia, Eritrea, India, Bangladesh, and Nepal. Its resilience to both drought and flooding makes it a ...promising crop for ensuring food security in a changing climate. The lack of genetic resources and the crop's association with the disease neurolathyrism have limited the cultivation of grass pea. Here, we present an annotated, long read-based assembly of the 6.5 Gbp L. sativus genome. Using this genome sequence, we have elucidated the biosynthetic pathway leading to the formation of the neurotoxin, β-L-oxalyl-2,3-diaminopropionic acid (β-L-ODAP). The final reaction of the pathway depends on an interaction between L. sativus acyl-activating enzyme 3 (LsAAE3) and a BAHD-acyltransferase (LsBOS) that form a metabolon activated by CoA to produce β-L-ODAP. This provides valuable insight into the best approaches for developing varieties which produce substantially less toxin.
Grass pea has the potential to become a miracle crop if the stigma attached to it as a toxic plant is ignored. In light of the following, we conducted transcriptome analyses on the high and low ...ODAP-containing cultivars i.e., Nirmal and Bidhan respectively in both normal and salt stress conditions. In this study, genes that work upstream and downstream to β-ODAP have been found. Among these genes, AAO3 and ACL5 were related to ABA and polyamine biosynthesis, showing the relevance of ABA and polyamines in boosting the β-ODAP content in Nirmal. Elevated β-ODAP levels in salt stress-treated Bidhan may have evolved tolerance by positively regulating the expression of genes involved in phenylpropanoid and jasmonic acid biosynthesis. Although the concentration of β-ODAP in Bidhan increased under salt stress, it was lower than in stress-treated Nirmal. Despite this, the expression of stress-related genes that work downstream to β-ODAP was found higher in stress-treated Bidhan. This could be because stress-treated Nirmal has lower GSH, proline, and higher H2O2, resulting in the development of severe oxidative stress. Overall, our research not only identified new genes linked with β-ODAP, but also revealed the molecular mechanism by which a low β-ODAP-containing cultivar developed tolerance against salinity stress.
•Bidhan is a low-β-ODAP cultivar having salinity stress tolerance.•β-ODAP production is largely regulated by genes involved in ABA and polyamine biosynthesis.•Elevated β-ODAP in stress-treated Bidhan develops tolerance by positive regulation of phenylpropanoid and jasmonic acid biosynthesis related genes.•Elevated level of GSH and proline provides salinity stress tolerance to Bidhan.
Point mutations result from errors made during DNA replication or repair, so they are usually expected to be homogeneous across all regions of a genome. However, we have found a region of chloroplast ...DNA in plants related to sweetpea (Lathyrus) whose local point mutation rate is at least 20 times higher than elsewhere in the same molecule. There are very few precedents for such heterogeneity in any genome, and we suspect that the hypermutable region may be subject to an unusual process such as repeated DNA breakage and repair. The region is 1.5 kb long and coincides with a gene, ycf4, whose rate of evolution has increased dramatically. The product of ycf4, a photosystem I assembly protein, is more divergent within the single genus Lathyrus than between cyanobacteria and other angiosperms. Moreover, ycf4 has been lost from the chloroplast genome in Lathyrus odoratus and separately in three other groups of legumes. Each of the four consecutive genes ycf4-psaI-accD-rps16 has been lost in at least one member of the legume "inverted repeat loss" clade, despite the rarity of chloroplast gene losses in angiosperms. We established that accD has relocated to the nucleus in Trifolium species, but were unable to find nuclear copies of ycf4 or psaI in Lathyrus. Our results suggest that, as well as accelerating sequence evolution, localized hypermutation has contributed to the phenomenon of gene loss or relocation to the nucleus.
The impact of lead nitrate (Pb(NO
3)
2; 0.5
mM) on steady-state accumulation of messengers corresponding to stress responsive genes was studied in two local lines of 11-d grass pea (
Lathyrus
sativus ...L.) plants exposed for 96
h in a hydroponic system. Real-time reverse transcription polymerase chain reaction technique was used with grass pea-specific primers designed from newly isolated partial cDNA. Increases in accumulation of glutathione reductase, ascorbate peroxidase and glutathione S-transferase transcripts suggested that roots enhanced detoxification mechanisms involving glutathione. In the leaves where no lead was translocated, the pollutant indirectly triggered increases in expression of several genes. This process probably resulted from systemic signals originating from the roots where lead accumulated in large amounts, approximately 150
mg Pb
g
−1 dry weight. A preventive and/or adaptive role for the signal is assumed, since it concerned genes implicated in reactive oxygen species scavenging (ascorbate peroxidase), protein protection (heat shock protein 70) and proteolysis (cysteine and aspartic proteases).
Lathyrus L. is an important genus contributing in human food, animal feed and fodder. The genetic variation is studied among and within six species sampled over a large geographical area: Lathyrus ...cicera, Lathyrus sativus, Lathyrus sylvestris, Lathyrus tuberosus, Lathyrus ochrus and Lathyrus aphaca. The phylogenetic relationship among these species was assessed using sequences of chloroplast DNA trnH-psbA (intergenic spacer). The highly polymorphic spacer' length was 330 bp. The phylogenetic analyses using Maximum Parsimony and Genetic Distances, agreed with the universal taxonomy of Kupicha. L. sativus and L. cicera could be considered as sister species, sharing a common ancestor.
•Phylogenetic relationships were elucidated among and between Lathyrus species.•trnH-psbA barcode was well conserved at the intrapopulation level.•The spacer revealed high level of polymorphism between populations Lathyrus.
Grasspea, often regarded as an orphan legume, is recognized to be fairly tolerant to water-deficit stress. In the present study, 3-week-old grasspea seedlings were subjected to dehydration by ...withholding water over a period of 144 h. While there were no detectable phenotypic changes in the seedlings till 48 h, the symptoms appeared during 72 h and aggravated upon prolonged dehydration. The physiological responses to water-deficit stress during 72–96 h displayed a decrease in pigments, disruption in membrane integrity and osmotic imbalance. We evaluated the temporal effects of dehydration at the transcriptome and metabolome levels. In total, 5201 genes of various functional classes including transcription factors, cytoplasmic enzymes and structural cell wall proteins, among others, were found to be dehydration-responsive. Further, metabolome profiling revealed 59 dehydration-responsive metabolites including sugar alcohols and amino acids. Despite the lack of genome information of grasspea, the time course of physicochemical and molecular responses suggest a synchronized dehydration response. The cross-species comparison of the transcriptomes and metabolomes with other legumes provides evidence for marked molecular diversity. We propose a hypothetical model that highlights novel biomarkers and explain their relevance in dehydration-response, which would facilitate targeted breeding and aid in commencing crop improvement efforts.
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