Nitrogen (N) is one of the most important mineral elements for plant growth and development and a key factor for improving crop yield. Rapeseed,
, is the largest oil crop in China, producing more ...than 50% of the domestic vegetable oil. However, high N fertilizer input with low utilization efficiency not only increases the production cost but also causes serious environmental pollution. Therefore, the breeding of rapeseed with high N efficiency is of great strategic significance to ensure the security of grain and oil and the sustainable development of the rapeseed industry. In order to provide reference for genetic improvement of rapeseed N-efficient utilization, in this article, we mainly reviewed the recent research progress of rapeseed N efficiency, including rapeseed N efficiency evaluation, N-efficient germplasm screening, and N-efficient physiological and molecular genetic mechanisms.
Clubroot caused by Plasmodiophora brassicae led to a significant decrease in the yield and quality of Brassica napus, one of the most important oil crops in the world. JAZ proteins are an essential ...repressor of jasmonates (JAs) signaling cascades, which have been reported to regulate the resistance to P. brassicae in B. napus. In this study, we identified 51, 25 and 26 JAZ proteins in B. napus, B. rapa and B. oleracea, respectively. Phylogenetic analysis displayed that the notedJAZ proteins were divided into six groups. The JAZ proteins clustered in the same group shared a similar motif composition and distribution order. The 51 BnaJAZs were not evenly assigned on seventeen chromosomes in B. napus, except for A04 and C07. The BnaJAZs of the AtJAZ7/AtJAZ8 group presented themselves to be significantly up-regulated after inoculation by P. brassicae. Variation analysis in a population with a specific resistance performance in P. brassicae displayed a 64 bp translocation in BnaC03T0663300ZS (BnaJAZ8.C03, homologous to AtJAZ8) with an 8% reduction in the disease index on average. Through protein–protein interaction analysis, 65 genes were identified that might be involved in JAZ8 regulation of resistance to P. brassicae in B. napus, which provided new clues for understanding the resistance mechanism to P. brassicae.
displays remarkable morphological variations. It intrigued researchers to study the underlying cause of the enormous diversification of this organism. However, genomic variations in complex heading ...traits are less known in
. Herein, we performed a comparative population genomics analysis to explore structural variations (SVs) responsible for heading trait formation in
. Synteny analysis showed that chromosomes C1 and C2 of
(CC) shared strong collinearity with A01 and A02 of
(AA), respectively. Two historical events, whole genome triplication (WGT) of
species and differentiation time between AA and CC genomes, were observed clearly by phylogenetic and Ks analysis. By comparing heading and non-heading populations of
genomes, we found extensive SVs during the diversification of the
genome. We identified 1205 SVs that have an impact on 545 genes and might be associated with the heading trait of cabbage. Overlapping the genes affected by SVs and the differentially expressed genes identified by RNA-seq analysis, we identified six vital candidate genes that may be related to heading trait formation in cabbage. Further, qRT-PCR experiments also verified that six genes were differentially expressed between heading leaves and non-heading leaves, respectively. Collectively, we used available genomes to conduct a comparison population genome analysis and identify candidate genes for the heading trait of cabbage, which provides insight into the underlying reason for heading trait formation in
.
The chlorophyll content has a direct effect on photosynthesis of crops. In order to explore a quick and convenient method for estimating the chlorophyll content of Brassica napus and facilitate ...efficient crop monitoring, we measured the actual value of chlorophyll with a SPAD-502 chlorophyll detector, and collected aerial images of B. napus with an unmanned aerial vehicle (UAV) carrying a RGB camera in this study. The total number of 270 samples collected images were divided into regions according to the planting conditions of different B. napus varieties in the field. Then, according to the empirical formula, there were 36 colors’ characteristic parameters calculated and combined. To estimate the chlorophyll content of rape, 189 samples were included in the modeling set, while the other 81 samples were enrolled in the validation set for testing the accuracy of this model. After the combination of R (red), G (green) and B (blue) color channels, the results showed that the color characteristics B/(R + G), b, B/G, (G-B)/(G + B), g-b were highly connected with the measured value of chlorophyll SPAD, and the correlation coefficient between the combination based on B/(R + G) and SPAD value was 0.747. With R2 = 0.805, RMSE = 3.343, and RE = 6.84%, the regression model created using random forest had superior outcomes, according to the model comparison. This study offers a new method for quickly estimating the amount of chlorophyll in rapeseed and a workable reference for crop monitoring using the UAV platform.
Rapeseed (Brassica napus L.) is an important oil-producing crop for the world. Its adaptation, yield and quality have been considerably improved in recent decades, but the genomic basis underlying ...successful breeding selection remains unclear. Hence, we conducted a comprehensive genomic assessment of rapeseed in the breeding process based on the whole-genome resequencing of 418 diverse rapeseed accessions. We unraveled the genomic basis for the selection of adaptation and agronomic traits. Genome-wide association studies identified 628 associated loci-related causative candidate genes for 56 agronomically important traits, including plant architecture and yield traits. Furthermore, we uncovered nonsynonymous mutations in plausible candidate genes for agronomic traits with significant differences in allele frequency distributions across the improvement process, including the ribosome recycling factor (BnRRF) gene for seed weight. This study provides insights into the genomic basis for improving rapeseed varieties and a valuable genomic resource for genome-assisted rapeseed breeding.
Main conclusions
A novel image-based screening method for precisely identifying genotypic variations in rapeseed RSA under waterlogging stress was developed. Five key root traits were confirmed as ...good indicators of waterlogging and might be employed in breeding, particularly when using the MFVW approach.
Waterlogging is a vital environmental factor that has detrimental effects on the growth and development of rapeseed (
Brassica napus
L.). Plant roots suffer from hypoxia under waterlogging, which ultimately confers yield penalty. Therefore, it is crucially important to understand the genetic variation of root system architecture (RSA) in response to waterlogging stress to guide the selection of new tolerant cultivars with favorable roots. This research was conducted to investigate RSA traits using image-based screening techniques to better understand how RSA changes over time during waterlogging at the seedling stage. First, we performed a
t
-test by comparing the relative root trait value between four tolerant and four sensitive accessions. The most important root characteristics associated with waterlogging tolerance at 12 h are total root length (TRL), total root surface area (TRSA), total root volume (TRV), total number of tips (TNT), and total number of forks (TNF). The root structures of 448 rapeseed accessions with or without waterlogging showed notable genetic diversity, and all traits were generally restrained under waterlogging conditions, except for the total root average diameter. Additionally, according to the evaluation and integration analysis of 448 accessions, we identified that five traits, TRL, TRSA, TRV, TNT, and TNF, were the most reliable traits for screening waterlogging-tolerant accessions. Using analysis of the membership function value (MFVW) and D-value of the five selected traits, 25 extremely waterlogging-tolerant materials were screened out. Waterlogging significantly reduced RSA, inhibiting root growth compared to the control. Additionally, waterlogging increased lipid peroxidation, accompanied by a decrease in the activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT). This study effectively improves our understanding of the response of RSA to waterlogging. The image-based screening method developed in this study provides a new scientific guidance for quickly examining the basic RSA changes and precisely predicting waterlogging-tolerant rapeseed germplasms, thus expanding the genetic diversity of waterlogging-tolerant rapeseed germplasm available for breeding.
The isochorismate synthase (ICS) proteins are essential regulators of salicylic acid (SA) synthesis, which has been reported to regulate resistance to biotic and abiotic stresses in plants. Clubroot ...caused by Plasmodiophora brassicae is a common disease that threatens the yield and quality of Oilseed rape (Brassica napus L.). Exogenous application of salicylic acid reduced the incidence of clubroot in oilseed rape. However, the potential importance of the ICS genes family in B. napus and its diploid progenitors has been unclear. Here, we identified 16, 9, and 10 ICS genes in the allotetraploid B. napus, diploid ancestor Brassica rapa and Brassica oleracea, respectively. These ICS genes were classified into three subfamilies (I-III), and member of the same subfamilies showed relatively conserved gene structures, motifs, and protein domains. Furthermore, many hormone-response and stress-related promoter cis-acting elements were observed in the BnaICS genes. Exogenous application of SA delayed the growth of clubroot galls, and the expression of BnaICS genes was significantly different compared to the control groups. Protein-protein interaction analysis identified 58 proteins involved in the regulation of ICS in response to P. brassicae in B. napus. These results provide new clues for understanding the resistance mechanism to P. brassicae.
•The first genome-wide analysis of isochorismate synthase genes in Brassica ssp.•A total of 35 ICSs were identified and characterized.•Most of the BnaICS genes had the highest level of expression in root.•Exogenous application of salicylic acid can delay the growth of clubroot galls.•The excellent haplotype of BnaICS7 and BnaICS15 markedly reduced the disease index.
The cultivated diploid Brassica oleracea is an important vegetable crop, but the genetic basis of its domestication remains largely unclear in the absence of high-quality reference genomes of wild B. ...oleracea. Here, we report the first chromosome-level assembly of the wild Brassica oleracea L. W03 genome (total genome size, 630.7 Mb; scaffold N50, 64.6 Mb). Using the newly assembled W03 genome, we constructed a gene-based B. oleracea pangenome and identified 29 744 core genes, 23 306 dispensable genes, and 1896 private genes. We re-sequenced 53 accessions, representing six potential wild B. oleracea progenitor species. The results of the population genomic analysis showed that the wild B. oleracea populations had the highest level of diversity and represents the most closely related population to modern-day horticultural B. oleracea. In addition, the WUSCHEL gene was found to play a decisive role in domestication and to be involved in cauliflower and broccoli curd formation. We also illustrate the loss of disease-resistance genes during selection for domestication. Our results provide new insights into the domestication of B. oleracea and will facilitate the future genetic improvement of Brassica crops.
Summary
Improving yield is a primary mission for cotton (Gossypium hirsutum) breeders; development of cultivars with suitable architecture for high planting density (HPDA) can increase yield per unit ...area.
We characterized a natural cotton mutant, AiSheng98 (AS98), which exhibits shorter height, shorter branch length, and more acute branch angle than wild‐type.
A copy number variant at the HPDA locus on Chromosome D12 (HPDA‐D12), encoding a dehydration‐responsive element‐binding (DREB) transcription factor, GhDREB1B, strongly affects plant architecture in the AS98 mutant. We found an association between a tandem duplication of a c. 13.5 kb segment in HPDA‐D12 and elevated GhDREB1B expression resulting in the AS98 mutant phenotype. GhDREB1B overexpression confers a significant decrease in plant height and branch length, and reduced branch angle.
Our results suggest that fine‐tuning GhDREB1B expression may be a viable engineering strategy for modification of plant architecture favorable to high planting density in cotton.
Brassica oleracea displays remarkable morphological variations. It intrigued researchers to study the underlying cause of the enormous diversification of this organism. However, genomic variations in ...complex heading traits are less known in B. oleracea. Herein, we performed a comparative population genomics analysis to explore structural variations (SVs) responsible for heading trait formation in B. oleracea. Synteny analysis showed that chromosomes C1 and C2 of B. oleracea (CC) shared strong collinearity with A01 and A02 of B. rapa (AA), respectively. Two historical events, whole genome triplication (WGT) of Brassica species and differentiation time between AA and CC genomes, were observed clearly by phylogenetic and Ks analysis. By comparing heading and non-heading populations of B. oleracea genomes, we found extensive SVs during the diversification of the B. oleracea genome. We identified 1205 SVs that have an impact on 545 genes and might be associated with the heading trait of cabbage. Overlapping the genes affected by SVs and the differentially expressed genes identified by RNA-seq analysis, we identified six vital candidate genes that may be related to heading trait formation in cabbage. Further, qRT-PCR experiments also verified that six genes were differentially expressed between heading leaves and non-heading leaves, respectively. Collectively, we used available genomes to conduct a comparison population genome analysis and identify candidate genes for the heading trait of cabbage, which provides insight into the underlying reason for heading trait formation in B. oleracea.
