Summary
The Cucurbita genus (squashes, pumpkins and gourds) includes important domesticated species such as C. pepo, C. maxima and C. moschata. In this study, we present a high-quality draft of the zucchini (C. pepo) genome. The assembly has a size of 263 Mb, a scaffold N50 of 1.8 Mb and 34 240 gene models. It includes 92% of the conserved BUSCO core gene set, and it is estimated to cover 93.0% of the genome. The genome is organized in 20 pseudomolecules that represent 81.4% of the assembly, and it is integrated with a genetic map of 7718 SNPs. Despite the small genome size, three independent lines of evidence support that the C. pepo genome is the result of a whole-genome duplication: the topology of the gene family phylogenies, the karyotype organization and the distribution of 4DTv distances. Additionally, 40 transcriptomes of 12 species of the genus were assembled and analysed together with all the other published genomes of the Cucurbitaceae family. The duplication was detected in all the Cucurbita species analysed, including C. maxima and C. moschata, but not in the more distant cucurbits belonging to the Cucumis and Citrullus genera, and it is likely to have occurred 30 ± 4 Mya in the ancestral species that gave rise to the genus.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/pbi.12860

De novo assembly of the zucchini genome reveals a whole-genome duplication associated with the origin of the Cucurbita genus.

Conserved genomic context provides critical information for comparative evolutionary analysis. With the increase in numbers of sequenced plant genomes, synteny analysis can provide new insights into gene family evolution. Here, we exploit a network analysis approach to organize and interpret massive pairwise syntenic relationships. Specifically, we analyzed synteny networks of the MADS-box transcription factor gene family using 51 completed plant genomes. In combination with phylogenetic profiling, several novel evolutionary patterns were inferred and visualized from synteny network clusters. We found lineage-specific clusters that derive from transposition events for the regulators of floral development (APETALA3 and PI) and flowering time (FLC) in the Brassicales and for the regulators of root development (AGL17) in Poales. We also identified two large gene clusters that jointly encompass many key phenotypic regulatory Type II MADS-box gene clades (SEP1, SQUA, TM8, SEP3, FLC, AGL6, and TM3). Gene clustering and gene trees support the idea that these genes are derived from an ancient tandem gene duplication that likely predates the radiation of the seed plants and then expanded by subsequent polyploidy events. We also identified angiosperm-wide conservation of synteny of several other less studied clades. Combined, these findings provide new hypotheses for the genomic origins, biological conservation, and divergence of MADS-box gene family members.

/pdf/phylogenomic-synteny-network-analysis-of-mads-box-24flg4w8jy.pdf

Phylogenomic Synteny Network Analysis of MADS-Box Transcription Factor Genes Reveals Lineage-Specific Transpositions, Ancient Tandem Duplications, and Deep Positional Conservation.

Lotus (Nelumbo nucifera) is a perennial aquatic basal eudicot belonging to a small family Nelumbonaceace, which contains only one genus with two species. It is an important horticultural plant, with its uses ranging from ornamental, nutritional to medicinal values, and has been widely used, especially in Southeast Asia. Recently, the lotus obtained a lot of attention from the scientific community. An increasing number of research papers focusing on it have been published, which have shed light on the mysteries of this species. Here, we comprehensively reviewed the latest advancement of studies on the lotus, including phylogeny, genomics and the molecular mechanisms underlying its unique properties, its economic important traits, and so on. Meanwhile, current limitations in the research of the lotus were addressed, and the potential prospective were proposed as well. We believe that the lotus will be an important model plant in horticulture with the generation of germplasm suitable for laboratory operation and the establishment of a regeneration and transformation system.

https://www.mdpi.com/1422-0067/20/15/3680/pdf

The Latest Studies on Lotus (Nelumbo nucifera)-an Emerging Horticultural Model Plant.

For most sequenced flowering plants, multiple whole-genome duplications (WGDs) are found. Duplicated genes following WGD often have different fates that can quickly disappear again, be retained for long(er) periods, or subsequently undergo small-scale duplications. However, how different expression, epigenetic regulation, and functional constraints are associated with these different gene fates following a WGD still requires further investigation due to successive WGDs in angiosperms complicating the gene trajectories. In this study, we investigate lotus (Nelumbo nucifera), an angiosperm with a single WGD during the K-pg boundary. Based on improved intraspecific-synteny identification by a chromosome-level assembly, transcriptome, and bisulfite sequencing, we explore not only the fundamental distinctions in genomic features, expression, and methylation patterns of genes with different fates after a WGD but also the factors that shape post-WGD expression divergence and expression bias between duplicates. We found that after a WGD genes that returned to single copies show the highest levels and breadth of expression, gene body methylation, and intron numbers, whereas the long-retained duplicates exhibit the highest degrees of protein-protein interactions and protein lengths and the lowest methylation in gene flanking regions. For those long-retained duplicate pairs, the degree of expression divergence correlates with their sequence divergence, degree in protein-protein interactions, and expression level, whereas their biases in expression level reflecting subgenome dominance are associated with the bias of subgenome fractionation. Overall, our study on the paleopolyploid nature of lotus highlights the impact of different functional constraints on gene fate and duplicate divergence following a single WGD in plant.

https://biblio.ugent.be/publication/8660644/file/8672012.pdf

Distinct Expression and Methylation Patterns for Genes with Different Fates following a Single Whole-Genome Duplication in Flowering Plants

The chloroplast genome is important for plant development and plant evolution. Nelumbo nucifera is one member of relict plants surviving from the late Cretaceous. Recently, a new sequencing platform PacBio RS II, known as `SMRT (Single Molecule, Real-Time) sequencing’, has been developed. Using the SMRT sequencing to investigate the chloroplast genome of N. nucifera will help to elucidate the plastid evolution of basal eudicots. The sizes of the de novo assembled complete chloroplast genome of N. nucifera were 163,307 bp, 163,747 bp and 163,600 bp with average depths of coverage of 7×, 712× and 105× sequenced by Sanger, Illumina MiSeq and PacBio RS II, respectively. The precise chloroplast genome of N. nucifera was obtained from PacBio RS II data proofread by Illumina MiSeq reads, with a quadripartite structure containing a large single copy region (91,846 bp) and a small single copy region (19,626 bp) separated by two inverted repeat regions (26,064 bp). The genome contains 113 different genes, including four distinct rRNAs, 30 distinct tRNAs and 79 distinct peptide-coding genes. A phylogenetic analysis of 133 taxa from 56 orders indicated that Nelumbo with an age of 177 million years is a sister clade to Platanus, which belongs to the basal eudicots. Basal eudicots began to emerge during the early Jurassic with estimated divergence times at 197 million years using MCMCTree. IR expansions/contractions within the basal eudicots seem to have occurred independently. Because of long reads and lack of bias in coverage of AT-rich regions, PacBio RS II showed a great promise for highly accurate `finished’ genomes, especially for a de novo assembly of genomes. N. nucifera is one member of basal eudicots, however, evolutionary analyses of IR structural variations of N. nucifera and other basal eudicots suggested that IR expansions/contractions occurred independently in these basal eudicots or were caused by independent insertions and deletions. The precise chloroplast genome of N. nucifera will present new information for structural variation of chloroplast genomes and provide new insight into the evolution of basal eudicots at the primary sequence and structural level.

https://link.springer.com/content/pdf/10.1186%2Fs12870-014-0289-0.pdf

A precise chloroplast genome of Nelumbo nucifera (Nelumbonaceae) evaluated with Sanger, Illumina MiSeq, and PacBio RS II sequencing platforms: insight into the plastid evolution of basal eudicots.

Sacred lotus (Nelumbo nucifera) is an ornamental plant that is also used for food and medicine. This basal eudicot species is especially important from an evolutionary perspective, as it occupies a critical phylogenetic position in flowering plants. Here we report the draft genome of a wild strain of sacred lotus. The assembled genome is 792 Mb, which is approximately 85-90% of genome size estimates. We annotated 392 Mb of repeat sequences and 36,385 protein-coding genes within the genome. Using these sequence data, we constructed a phylogenetic tree and confirmed the basal location of sacred lotus within eudicots. Importantly, we found evidence for a relatively recent whole-genome duplication event; any indication of the ancient paleo-hexaploid event was, however, absent. Genomic analysis revealed evidence of positive selection within 28 embryo-defective genes and one annexin gene that may be related to the long-term viability of sacred lotus seed. We also identified a significant expansion of starch synthase genes, which probably elevated starch levels within the rhizome of sacred lotus. Sequencing this strain of sacred lotus thus provided important insights into the evolution of flowering plant and revealed genetic mechanisms that influence seed dormancy and starch synthesis.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/tpj.12313

The sacred lotus genome provides insights into the evolution of flowering plants

The invention discloses a watercress protection land substrate culture method, and belongs to the field of watercress protection land substrate culture. The watercress protection land substrate culture method comprises the following steps that (1) a greenhouse is built, and a pool is built in the greenhouse; (2) the pool is filled with substrates; (3) seeding and seedling culture are carried out, and the fixed planting of watercress is carried out in the pool; (4) growth management is carried out; (5) harvesting and obtaining are realized. The watercress protection land substrate culture method has the advantages that the protection land is adopted for culturing the watercress, peat, mushroom slag and vermiculite are mixed to be used as the substrates, the fixed planting density of the watercress is optimized, in addition, the harvesting is carried out at proper time, the three times of harvesting is achieved in one year, the watercress yield is obviously improved, the watercress quality is improved, and the planting benefits of the watercress are improved.

Watercress protection land substrate culture method

The invention discloses an artificial hybridization breeding method for water chestnuts, and relates to the technical field of agricultural breeding. The artificial hybridization breeding method for the water chestnuts includes respectively selectively cultivating male parent water chestnuts and female parent water chestnuts; bagging male parent flower buds with just cracking sepals and petals yet to be loose, selecting female parent flower buds with just cracking sepals, removing the sepals and the petals, pinching off stamens and bagging the male parent flower buds and the female parent flower buds; pollinating female parent flowers by pollen of the male parent water chestnuts in 0-4 hours after the stamens of the female parent flower buds are removed. The male parent water chestnuts flower for 0-4.5 h before the female parent flowers are pollinated by the pollen of the male parent water chestnuts. The artificial hybridization breeding method has the advantage that hybrid water chestnut seeds with strong growth vigor and stress resistance and obvious hybrid vigor can be directionally selectively bred by the aid of artificial hybridization technologies.

Artificial hybridization breeding method for water chestnuts

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The sacred lotus genome provides insights into the evolution of flowering plants

Watercress protection land substrate culture method

Artificial hybridization breeding method for water chestnuts