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Chinese cabbage, Brassica rapa L. subsp. pekinensis is a crucial and extensively consumed vegetable in the world, especially Eastern Asia. The market demand for this leafy vegetable increases year by year, resulting in multiple challenges for agricultural researchers worldwide. Multi-omic approaches and the integration of functional genomics helps us understand the relationships between Chinese cabbage genomes and phenotypes under specific physiological and environmental conditions. However, challenges exist in integrating multi-omics for the functional analysis of genes and for developing potential traits for Chinese cabbage improvement. However, the panomics platform allows for the integration of complex omics, enhancing our understanding of molecular regulator networks in Chinese cabbage agricultural traits. In addition, the agronomic features of Chinese cabbage are significantly impacted by the environment. The expression of these agricultural features is tightly regulated by a combination of signals from both the internal regulatory network and the external growth environment. To comprehend the molecular process of these characteristics, it is necessary to have a prior understanding of molecular breeding for the objective of enhancing quality. While the use of various approaches in Chinese cabbage is still in its early stages, recent research has shown that it has the potential to uncover new regulators both rapidly and effectively, leading to updated regulatory networks. In addition, the utilization of the efficient transformation technique in conjunction with gene editing using CRISPR/Cas9 will result in a reduction in time requirements and facilitate a more precise understanding of the role of the regulators. Numerous studies about Chinese cabbage have been conducted in the past two decades, but a comprehensive review about its genome still limited. This review provides a concise summary of the latest discoveries in genomic research related to Brassica and explores the potential future developments for this species. [ABSTRACT FROM AUTHOR]

In plants, heteromorphic self-incompatibility (HetSI) is a strategy for avoiding self-pollination and promoting outcrossing, and during this process, numerous protein-protein interaction events occur between the pistil and pollen. Previous studies in Primula and Fagopyrum that focused on HetSI systems have provided interesting insights; however, the molecular mechanism underlying HetSI remains largely unknown. In this study, we profiled the proteome of Plumbago auriculata stigmas before and after self-incompatible (SI) and self-compatible (SC) pollination. Comparative analyses were conducted by 4D-DIA (Four-dimensional data independent acquisition), a promising technology that increases the sensitivity and reduces the spectral complexity of proteomic analysis by adding a fourth dimension, ion mobility. The results revealed 33387 peptides and 5311 proteins in all samples. The pathways in which the differentially expressed proteins (DEPs) identified in the P × P (Pin style self-pollinated with pin pollen) vs. PS (Pin style) and T × T (Thrum style self-pollinated with thrum pollen) vs. TS (Thrum style) comparisons were significantly enriched were biosynthesis of secondary metabolites and pentose and glucuronate interconversions. In the P × T (Pin style cross-pollinated with thrum pollen) vs. PS and T × P (Thrum style cross-pollinated with pin pollen) vs. TS comparison, the top three pathways were biosynthesis of secondary metabolites, pentose and glucuronate interconversions, and phenylpropanoid biosynthesis. The phenylpropanoid biosynthesis, cutin, suberine and wax biosynthesis, and flavonoid biosynthesis pathways were enriched in the P × T vs. P × P comparison, and starch and sucrose metabolism, glycerophospholipid metabolism, and alpha-linolenic acid metabolism were abundant in the T × T vs. T × P comparison. The enriched pathways between PS and TS were the biosynthesis of secondary metabolites, phenylpropanoid biosynthesis, and pentose and glucuronate interconversion. Self-incompatibility protein S1 (SI S1), Mitogen-activated protein kinase 3/4 (MPK3/4), Mitogen-activated protein kinase kinase 2/3 (M2K2/3), Exocyst complex component EXO70A1 (E70A1) and Thioredoxin H1/2 (TRXH1/2) were found to be HetSI-related candidates, and O-fucosyltransferase 23 (OFT23), 3- ketoacyl-CoA synthase 6 (KCS6), Receptor-like protein kinase FERONIA (FERON), Fimbrin-5 (FIMB5), Pollen-specific leucine-rich repeat extensin-like protein 4 (PLRX4), Transcription initiation factor IIB-2 (TF2B2) and Pectinesterase 1 (AL11A), etc., were identified as other regulatory transducers. These findings combined with our morphological and reactive oxygen species (ROS) intensity analyses indicate that P. auriculata has typical dry-stigmas and that the HetSI mechanism might differ between the pin and thrum. SI S1 might be the key factor in HetSI, and ROS are overexpressed during SC pollination to rapidly activate the mitogen-activated protein kinase (MAPK)-mediated phosphorylation of E70A1 to maintain stigma receptivity in plants with HetSI. [ABSTRACT FROM AUTHOR]

The interaction and coevolution between nuclear and cytoplasmic genomes are one of the fundamental hallmarks of eukaryotic genome evolution and, 2 billion yr later, are still major contributors to the formation of new species. Although many studies have investigated the role of cytonuclear interactions following allopolyploidization, the relative magnitude of the effect of subgenome dominance versus cytonuclear interaction on genome evolution remains unclear. The Brassica triangle of U features 3 diploid species that together have formed 3 separate allotetraploid species on similar evolutionary timescales, providing an ideal system for understanding the contribution of the cytoplasmic donor to hybrid polyploid. Here, we investigated the evolutionary pattern of organelle-targeted genes in Brassica carinata (BBCC) and 2 varieties of Brassica juncea (AABB) at the whole-genome level, with particular focus on cytonuclear enzyme complexes. We found partial evidence that plastid-targeted genes experience selection to match plastid genomes, but no obvious corresponding signal in mitochondria-targeted genes from these 2 separately formed allopolyploids. Interestingly, selection acting on plastid genomes always reduced the retention rate of plastid-targeted genes encoded by the B subgenome, regardless of whether the Brassica nigra (BB) subgenome was contributed by the paternal or maternal progenitor. More broadly, this study illustrates the distinct selective pressures experienced by plastid- and mitochondria-targeted genes, despite a shared pattern of inheritance and natural history. Our study also highlights an important role for subgenome dominance in allopolyploid genome evolution, even in genes whose function depends on separately inherited molecules. [ABSTRACT FROM AUTHOR]

Lycopene cyclases (LCYs) are a key branching point in regulating the carotenoid biosynthesis pathway in plants. Bixa orellana L. is characterized by the presence in its seed of bixin, an apocarotenoid of significant importance in the food, pharmaceutical, and cosmetic industries. Gene analysis provides the opportunity to investigate the LCY gene structure in plant species and its relationship with the synthesis of carotenoids. Coding sequences of the LCY genes were retrieved from a B. orellana genome DNA. Boβ-LCY1 and Boβ-LCY2 genes exhibit 100% of identity to their respective cDNA accessions, and exhibit a single coding region of 1512 bp (504 aa) and 1495 bp (498 aa), respectively. In contrast, Boε-LCY gene shows a coding region of 1581 bp (527 aa) with 10 introns of diverse lengths. Putative Transcription Factors (TFs) binding sites were upstream (3000 bp) identified for each LCY gene. TFs cover two groups, one with the categories of photosynthesis, reproduction, and oxidative processes that are frequent. The second one with the categories of defense, cell cycle, signaling, and carbohydrate metabolism, which are poorly represented. Besides, repetitive DNA elements showed motifs and proteins related to LTR from the Ty3/Gypsy family, were associated with the TFs regions. In general, TFs vary in the different BoLCY genes, being more abundant in the Boε-LCY gene. LCY expression analyzed from a transcriptome database, and validated by RT-qPCR, shows an upregulation of the three LCYs, mainly oriented to the synthesis of essential carotenoids in photosynthetic tissues (leaves), as well as an upregulation of the Boβ-LCY2 gene in the non-photosynthetic tissues (firsts seed development stages) related to the bixin accumulation. [ABSTRACT FROM AUTHOR]

The Cichorium genus offers a unique opportunity to study the sporophytic selfincompatibility (SSI) system, being composed of species characterized by highly efficient self-incompatibility (e.g., C. intybus) and complete self-compatibility (e.g., C. endivia). To this end, the chicory genome was used to map seven previously identified SSI locus-associated markers. The region containing the S-locus was therefore restricted to an ~4 M bp window on chromosome 5. Among the genes predicted in this region, MDIS1 INTERACTING RECEPTOR LIKE KINASE 2 (ciMIK2) was particularly promising as a candidate for SSI. Its ortholog in Arabidopsis (atMIK2) is involved in pollen-stigma recognition reactions, and its protein structure is similar to that of S-receptor kinase (SRK), a key component of the SSI system in the Brassica genus. The amplification and sequencing of MIK2 in chicory and endive accessions revealed two contrasting scenarios. In C. endivia, MIK2 was fully conserved even when comparing different botanical varieties (i.e., smooth and curly endive). In C. intybus, 387 polymorphic positions and 3 INDELs were identified when comparing accessions of different biotypes all belonging to the same botanical variety (i.e., radicchio). The polymorphism distribution throughout the gene was uneven, with hypervariable domains preferentially localized in the LRR-rich extracellular region, putatively identified as the receptor domain. The gene was hypothesized to be under positive selection, as the nonsynonymous mutations were more than double the synonymous ones (dN/dS = 2.17). An analogous situation was observed when analyzing the first 500 bp of the MIK2 promoter: no SNPs were observed among the endive samples, whereas 44 SNPs and 6 INDELs were detected among the chicory samples. Further analyses are needed to confirm the role of MIK2 in SSI and to demonstrate whether the 23 species-specific nonsynonymous SNPs in the CDS and/or the species-specific 10 bp-INDEL found in a CCAAT box region of the promoter are responsible for the contrasting sexual behaviors of chicory and endive. [ABSTRACT FROM AUTHOR]

Angiosperms present an astonishing diversity of genome sizes that can vary intra‐ or interspecifically. The remarkable new cytogenomic data shed some light on our understanding of evolution, but few studies were performed with insular and mainland populations to test possible correlations with dispersal, speciation, and adaptations to insular environments. Here, patterns of cytogenomic diversity were assessed among geographic samples (ca. 114) of Crithmum maritimum (Apiaceae), collected across the Azores and Madeira archipelagos, as well as in adjacent continental areas of Portugal. Using flow cytometry, the results indicated a significant intraspecific genome size variation, spanning from reduced sizes in the insular populations to larger ones in the mainland populations. Moreover, there was a tendency for an increase in genome size along the mainland populations, associated with lower temperatures, higher precipitation, and lower precipitation seasonality. However, this gradient might be the result of historic phylogeographical events associated with previous dispersal and extinction of local populations. Overall, our findings provided evidence that smaller genome sizes might play a critical role in the colonization of islands, corroborating other studies that argue that organisms with smaller genomes use fewer resources, having a selective advantage under insular environments. Although further studies are needed to improve our understanding of the mechanisms underlying genome size evolution on islands, conservation strategies must be promoted to protect the rich cytogenomic diversity found among C. maritimum populations, which occur in coastal areas that are particularly threatened by human activity, pollution, invasive species, and climate changes. [ABSTRACT FROM AUTHOR]

Synteny, the ordering of sequences within homologous chromosomes, must be maintained within the genomes of sexually reproducing species for the sharing of alleles and production of viable, reproducing offspring. However, when the genomes of closely related species are compared, a loss of synteny is often observed. Unequal homologous recombination is the primary mechanism behind synteny loss, occurring more often in transposon rich regions, and resulting in the formation of chromosomal rearrangements. To examine patterns of synteny among three closely related, interbreeding, and wild Eucalyptus species, we assembled their genomes using long‐read DNA sequencing and de novo assembly. We identify syntenic and rearranged regions between these genomes and estimate that ~48% of our genomes remain syntenic while ~36% is rearranged. We observed that rearrangements highly fragment microsynteny. Our results suggest that synteny between these species is primarily lost through small‐scale rearrangements, not through sequence loss, gain, or sequence divergence. Further examination of identified rearrangements suggests that rearrangements may be altering the phenotypes of Eucalyptus species. Our study also underscores that the use of single reference genomes in genomic variation studies could lead to reference bias, especially given the scale at which we show potentially adaptive loci have highly diverged, deleted, duplicated and/or rearranged. This study provides an unbiased framework to look at potential speciation and adaptive loci among a rapidly radiating foundation species of woodland trees that are free from selective breeding seen in most crop species. [ABSTRACT FROM AUTHOR]

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Cytonuclear coordination between biparental-nuclear genomes and uniparental-cytoplasmic organellar genomes in plants is often resolved by genetic and transcriptional cytonuclear responses. Whether this mechanism also acts in allopolyploid members of other kingdoms is not clear. Additionally, cytonuclear coordination of interleaved allopolyploid cells/individuals within the same population is underexplored. The yeast Saccharomyces pastorianus provides the opportunity to explore cytonuclear coevolution during different growth stages and from novel dimensions. Using S. pastorianus cells from multiple growth stages in the same environment, we show that nuclear mitochondria-targeted genes have undergone both asymmetric gene conversion and growth stage-specific biased expression favoring genes from the mitochondrial genome donor (Saccharomyces eubayanus). Our results suggest that cytonuclear coordination in allopolyploid lager yeast species entails an orchestrated and compensatory genetic and transcriptional evolutionary regulatory shift. The common as well as unique properties of cytonuclear coordination underlying allopolyploidy between unicellular yeasts and higher plants offers novel insights into mechanisms of cytonuclear evolution associated with allopolyploid speciation. [ABSTRACT FROM AUTHOR]

Knowing how chromosome recombination works is essential for plant breeding. It enables the design of crosses between different varieties to combine desirable traits and create new ones. This is because the meiotic crossovers between homologous chromatids are not purely random, and various strategies have been developed to describe and predict such exchange events. Recent studies have used methylation data to predict chromosomal recombination in rice using machine learning models. This approach proved successful due to the presence of a positive correlation between the CHH context cytosine methylation and recombination rates in rice chromosomes. This paper assesses the question if methylation can be used to predict recombination in four plant species: Arabidopsis, maize, sorghum, and tomato. The results indicate a positive association between CHH context methylation and recombination rates in certain plant species, with varying degrees of strength in their relationships. The CG and CHG methylation contexts show negative correlation with recombination. Methylation data was key effectively in predicting recombination in sorghum and tomato, with a mean determination coefficient of 0.65 ± 0.11 and 0.76 ± 0.05, respectively. In addition, the mean correlation values between predicted and experimental recombination rates were 0.83 ± 0.06 for sorghum and 0.90 ± 0.05 for tomato, confirming the significance of methylomes in both monocotyledonous and dicotyledonous species. The predictions for Arabidopsis and maize were not as accurate, likely due to the comparatively weaker relationships between methylation contexts and recombination, in contrast to sorghum and tomato, where stronger associations were observed. To enhance the accuracy of predictions, further evaluations using data sets closely related to each other might prove beneficial. In general, this methylome-based method holds great potential as a reliable strategy for predicting recombination rates in various plant species, offering valuable insights to breeders in their quest to develop novel and improved varieties., (© 2024. The Author(s).)

SUMMARY: Self‐incompatibility in the Brassicaceae family is governed by SRK and SCR, which are two highly polymorphic genes located at the S‐locus. Previously, the Arabidopsis lyrata SRK and SCR genes were introduced into Arabidopsis thaliana to generate self‐incompatible lines. However, there are no reports showing that Brassica SRK and SCR genes confer self‐incompatibility in A. thaliana. Doing so would further advance the mechanistic understanding of self‐incompatibility in Brassicaceae. Therefore, we attempted to generate A. thaliana transformants showing the self‐recognition activity of Brassica rapa by introducing BrSCR along with a chimeric BrSRK (BrSRK chimera, in which the kinase domain of BrSRK was replaced with that of AlSKR‐b). We found that the BrSRK chimera and BrSCR of B. rapa S‐9 and S‐46 haplotypes, but not those of S‐29, S‐44, and S‐60 haplotypes, conferred self‐recognition activity in A. thaliana. Analyses of A. thaliana transformants expressing mutant variants of the BrSRK‐9 chimera and BrSCR‐9 revealed that mutations at the amino acid residues involved in BrSRK9–BrSCR9 interaction caused defects in the self‐incompatibility response. The method developed in this study for generating self‐incompatible A. thaliana transformants showing B. rapa self‐recognition activity will be useful for analysis of self‐recognition mechanisms in Brassicaceae. Significance Statement: Although self‐incompatible A. thaliana was constructed by introducing SRK and SCR of A. lyrata, it has not been reported that Brassica SRK and SCR genes confer self‐incompatibility in A. thaliana. We generated A. thaliana transformants showing the self‐recognition activity of B. rapa by introducing BrSCR with a BrSRK chimera, in which the kinase domain of BrSRK was replaced with that of AlSKR‐b. Our finding will be useful for analysis of self‐recognition mechanisms in Brassicaceae. [ABSTRACT FROM AUTHOR]

Whole-genome duplications (WGDs) are a prominent process of diversification in eukaryotes. The genetic and evolutionary forces that WGD imposes on cytoplasmic genomes are not well understood, despite the central role that cytonuclear interactions play in eukaryotic function and fitness. Cellular respiration and photosynthesis depend on successful interaction between the 3,000+ nuclear-encoded proteins destined for the mitochondria or plastids and the gene products of cytoplasmic genomes in multi-subunit complexes such as OXPHOS, organellar ribosomes, Photosystems I and II, and Rubisco. Allopolyploids are thus faced with the critical task of coordinating interactions between the nuclear and cytoplasmic genes that were inherited from different species. Because the cytoplasmic genomes share a more recent history of common descent with the maternal nuclear subgenome than the paternal subgenome, evolutionary "mismatches" between the paternal subgenome and the cytoplasmic genomes in allopolyploids might lead to the accelerated rates of evolution in the paternal homoeologs of allopolyploids, either through relaxed purifying selection or strong directional selection to rectify these mismatches. We report evidence from six independently formed allotetraploids that the subgenomes exhibit unequal rates of protein-sequence evolution, but we found no evidence that cytonuclear incompatibilities result in altered evolutionary trajectories of the paternal homoeologs of organelle-targeted genes. The analyses of gene content revealed mixed evidence for whether the organelle-targeted genes are lost more rapidly than the non-organelle-targeted genes. Together, these global analyses provide insights into the complex evolutionary dynamics of allopolyploids, showing that the allopolyploid subgenomes have separate evolutionary trajectories despite sharing the same nucleus, generation time, and ecological context. [ABSTRACT FROM AUTHOR]