RESUMEN
BACKGROUND: The co-occurrence of C4 and CAM photosynthesis in a single species seems to be unusual and rare. This is likely due to the difficulty in effectively co-regulating both pathways. Here, we conducted a comparative transcriptomic analysis of leaves and cotyledons of the C4-like species Sesuvium sesuvioides (Aizoaceae) using RNA-seq. RESULTS: When compared to cotyledons, phosphoenolpyruvate carboxylase 4 (PEPC4) and some key C4 genes were found to be up-regulated in leaves. During the day, the expression of NADP-dependent malic enzyme (NADP-ME) was significantly higher in cotyledons than in leaves. The titratable acidity confirmed higher acidity in the morning than in the previous evening indicating the induction of weak CAM in cotyledons by environmental conditions. Comparison of the leaves of S. sesuvioides (C4-like) and S. portulacastrum (C3) revealed that PEPC1 was significantly higher in S. sesuvioides, while PEPC3 and PEPC4 were up-regulated in S. portulacastrum. Finally, potential key regulatory elements involved in the C4-like and CAM pathways were identified. CONCLUSIONS: These findings provide a new species in which C4-like and CAM co-occur and raise the question if this phenomenon is indeed so rare or just hard to detect and probably more common in succulent C4 lineages.
Asunto(s)
Aizoaceae , Cotiledón , Perfilación de la Expresión Génica , Fotosíntesis , Hojas de la Planta , Cotiledón/genética , Cotiledón/metabolismo , Hojas de la Planta/metabolismo , Hojas de la Planta/genética , Fotosíntesis/genética , Aizoaceae/genética , Aizoaceae/metabolismo , Regulación de la Expresión Génica de las Plantas , Transcriptoma , Malato Deshidrogenasa/metabolismo , Malato Deshidrogenasa/genética , Fosfoenolpiruvato Carboxilasa/metabolismo , Fosfoenolpiruvato Carboxilasa/genética , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismoRESUMEN
Recent developments in plant genomics have enabled a comprehensive analysis of the medicinal potential of plants based on their gene repertoire. Genes of biosynthesis pathways can be discovered through comparative genomics and through integration of transcriptomic data. Data-driven discovery of specialized metabolites could accelerate research.
Asunto(s)
Plantas Medicinales , Plantas Medicinales/genética , Plantas Medicinales/metabolismo , Genómica , Vías Biosintéticas , Genoma de Planta , TranscriptomaRESUMEN
Amaranthaceae (incl. Chenopodiaceae) shows an immense diversity of C4 syndromes. More than 15 independent origins of C4 photosynthesis, and the largest number of C4 species in eudicots signify the importance of this angiosperm lineage in C4 evolution. Here, we conduct RNA-Seq followed by comparative transcriptome analysis of three species from Camphorosmeae representing related clades with different photosynthetic types: Threlkeldia diffusa (C3), Sedobassia sedoides (C2), and Bassia prostrata (C4). Results show that B. prostrata belongs to the NADP-ME type and core genes encoding for C4 cycle are significantly upregulated when compared with Sed. sedoides and T. diffusa. Sedobassia sedoides and B. prostrata share a number of upregulated C4-related genes; however, two C4 transporters (DIT and TPT) are found significantly upregulated only in Sed. sedoides. Combined analysis of transcription factors (TFs) of the closely related lineages (Camphorosmeae and Salsoleae) revealed that no C3-specific TFs are higher in C2 species compared with C4 species; instead, the C2 species show their own set of upregulated TFs. Taken together, our study indicates that the hypothesis of the C2 photosynthesis as a proxy towards C4 photosynthesis is questionable in Sed. sedoides and more in favour of an independent evolutionary stable state.
Asunto(s)
Amaranthaceae/genética , Chenopodiaceae/genética , Fotosíntesis/genética , Proteínas de Plantas/genética , Amaranthaceae/crecimiento & desarrollo , Carbono/metabolismo , Dióxido de Carbono/metabolismo , Isótopos de Carbono/metabolismo , Chenopodiaceae/crecimiento & desarrollo , Filogenia , Hojas de la Planta/genética , Hojas de la Planta/crecimiento & desarrollo , Proteínas de Plantas/clasificación , RNA-Seq , Transcriptoma/genéticaRESUMEN
Storage ability of trifoliate yam (Dioscorea dumetorum) is restricted by a severe post-harvest hardening (PHH) phenomenon, which starts within the first 24 h after harvest and renders tubers inedible. Previous work has only focused on the biochemical changes affecting PHH in D. dumetorum. To the best of our knowledge, the candidate genes responsible for the hardening of D. dumetorum have not been identified. Here, transcriptome analyses of D. dumetorum tubers were performed in yam tubers of four developmental stages: 4 months after emergence (4MAE), immediately after harvest (AH), 3 days after harvest (3DAH) and 14 days after harvest (14DAH) of four accessions (Bangou 1, Bayangam 2, Fonkouankem 1, and Ibo sweet 3) using RNA-Seq. In total, between AH and 3DAH, 165, 199, 128 and 61 differentially expressed genes (DEGs) were detected in Bayangam 2, Fonkouankem 1, Bangou 1 and Ibo sweet 3, respectively. Functional analysis of DEGs revealed that genes encoding for CELLULOSE SYNTHASE A (CESA), XYLAN O-ACETYLTRANSFERASE (XOAT), CHLOROPHYLL A/B BINDING PROTEIN1, 2, 3, 4 (LHCB1, LHCB2, LHCB3, and LCH4) and an MYB transcription factor were predominantly and significantly up-regulated 3DAH, implying that these genes were potentially involved in the PHH as confirmed by qRT-PCR. A hypothetical mechanism of this phenomenon and its regulation has been proposed. These findings provide the first comprehensive insights into gene expression in yam tubers after harvest and valuable information for molecular breeding against the PHH.
RESUMEN
Trifoliate yam (Dioscorea dumetorum) is one example of an orphan crop, not traded internationally. Post-harvest hardening of the tubers of this species starts within 24 h after harvesting and renders the tubers inedible. Genomic resources are required for D. dumetorum to improve breeding for non-hardening varieties as well as for other traits. We sequenced the D. dumetorum genome and generated the corresponding annotation. The two haplophases of this highly heterozygous genome were separated to a large extent. The assembly represents 485 Mbp of the genome with an N50 of over 3.2 Mbp. A total of 35,269 protein-encoding gene models as well as 9941 non-coding RNA genes were predicted, and functional annotations were assigned.
Asunto(s)
Dioscorea/genética , Genoma de Planta/genética , Genómica , Secuenciación Completa del Genoma , Anotación de Secuencia Molecular , Proteínas de Plantas/genética , ARN no Traducido/genéticaRESUMEN
BACKGROUND: Yams (Dioscorea spp.) are economically important food for millions of people in the humid and sub-humid tropics. Dioscorea dumetorum (Kunth) is the most nutritious among the eight-yam species, commonly grown and consumed in West and Central Africa. Despite these qualities, the storage ability of D. dumetorum is restricted by severe postharvest hardening of the tubers that can be addressed through concerted breeding efforts. The first step of any breeding program is bound to the study of genetic diversity. In this study, we used the Genotyping-By-Sequencing of Single Nucleotide Polymorphism (GBS-SNP) to investigate the genetic diversity and population structure of 44 accessions of D. dumetorum in Cameroon. Ploidy was inferred using flow cytometry and gbs2ploidy. RESULTS: We obtained on average 6371 loci having at least information for 75% accessions. Based on 6457 unlinked SNPs, our results demonstrate that D. dumetorum is structured into four populations. We clearly identified, a western/north-western, a western, and south-western populations, suggesting that altitude and farmers-consumers preference are the decisive factors for differential adaptation and separation of these populations. Bayesian and neighbor-joining clustering detected the highest genetic variability in D. dumetorum accessions from the south-western region. This variation is likely due to larger breeding efforts in the region as shown by gene flow between D. dumetorum accessions from the south-western region inferred by maximum likelihood. Ploidy analysis revealed diploid and triploid levels in D. dumetorum accessions with mostly diploid accessions (77%). Male and female accessions were mostly triploid (75%) and diploid (69%), respectively. The 1C genome size values of D. dumetorum accessions were on average 0.333 ± 0.009 pg and 0.519 ± 0.004 pg for diploids and triploids, respectively. CONCLUSIONS: Germplasm characterization, population structure and ploidy are an essential basic information in a breeding program as well as for conservation of intraspecific diversity. Thus, results obtained in this study provide valuable information for the improvement and conservation of D. dumetorum. Moreover, GBS appears as an efficient powerful tool to detect intraspecific variation.