Yellow seed is a desirable characteristic for the breeding of oilseed Brassica crops, but the manifestation of seed coat color is very intricate due to the involvement of various pigments, the main components of which are flavonols, proanthocyanidin (condensed tannin), and maybe some other phenolic relatives, like lignin and melanin. The focus of this review is to examine the genetics mechanism regarding the biosynthesis and regulation of these pigments in the seed coat of oilseed Brassica. This knowledge came largely from recent researches on the molecular mechanism of TRANSPARENT TESTA (tt) and similar mutations in the ancestry model plant of Brassica, Arabidopsis. Some key enzymes in the flavonoid (flavonols and proanthocyanidin) biosynthetic pathway have been characterized in tt mutants. Some orthologs to these TRANSPARENT TESTA genes have also been cloned in Brassica species. However, it is suggested that some alterative metabolism pathways, including lignin and melanin, might also be involved in seed color manifestation. Polyphenol oxidases, such as laccase, tyrosinase, or even peroxidase, participate in the oxidation step in proanthocyanidin, lignin, and melanin biosynthesis. Moreover, some researches also suggested that melanic pigment in black-seeded Brassica was several fold higher than in yellow-seeded Brassica. Although more experiments are required to evaluate the importance of lignin and melanin in seed coat browning, the current results suggest that the flavonols and proanthocyanidin are not the only roles affecting seed color.
Background: Acetolactate synthase (ALS)-inhibiting herbicides amidosulfuron (Hoestar) is an efficient gametocide that can induce male sterility in rapeseed (Brassica napus L.). We conducted an integrated study of cytological, transcriptomic, and physiological analysis to decipher the gametocidal effect of amidosulfuron.Results: In the first several days after exposure to amidosulfuron at a gametocidal dose of ca. 1 μg per plant, the plants showed the earliest symptoms including short retard of raceme elongation, slight chlorosis on leaf, and decrease of photosynthesis rate. Chloroplasts in leaf and anther epidermis, and tapetal plastids were deformed. Both tapetal cell and uni-nucleate microspore showed autophagic vacuoles and degenerated quickly. The amidosulfuron treatment caused reduction of photosynthetic rate and the contents of leaf chlorophyll, soluble sugar and pyruvate, as well as content alteration of several free amino acids in the treated plants. A comparison of transcriptomic profiling data of the young flower buds of the treated plants with the control identified 142 up-regulated and 201 down-regulated differential expression transcripts with functional annotations. Down-regulation of several interesting genes encoding PAIR1, SDS, PPD2, HFM1, CSTF77, A6, ALA6, UGE1, FLA20, A9, bHLH91, and putative cell wall protein LOC106368794, and up-regulation of autophagy-related protein ATG8A indicated functional abnormalities about cell cycle, cell wall formation, chloroplast structure, and tissue autophagy. Ethylene-responsive transcription factor RAP2-11-like was up-regulated in the flower buds and ethylene release rate was also elevated. The transcriptional regulation in the amidosulfuron-treated plants was in line with the cytological and physiological changes.Conclusions: The results suggested that metabolic decrease related to photosynthesis and energy supply are associated with male sterility induced by amidosulfuron. The results provide insights into the molecular mechanisms of gametocide-induced male sterility and expand the knowledge on the transcriptomic complexity of the plants exposure to sulfonylurea herbicide.
The genetic diversity and relationships among 63 rapeseed accessions, including 34 Chinese, 22 Czech, 2 Swedish, 2 German, one French and 2 Canadian accessions, were evaluated by nine agronomically important characters in the field at Yangling, Shaanxi, China. Significant differences between Chinese and European group in plant height, setting position of the first primary branch, number of siliques of the terminal raceme, thousand seed weight and seed yield per plant were detected. There were significant variations in nine agronomic characters among the tested rapeseed accessions. Ward's minimum variance cluster analysis based on Mahalanobis distances on the raw data of nine agronomic characters clearly separated the European accessions from the Chinese ones. However, the Chinese accessions with erucic acid free and/or low glucosinolates could not be separated from those Chinese accessions with both high erucic acid and glucosinolates. In general, cluster analysis of the 63 accessions based on the selected agronomic characters was consistent with known pedigree information and geographic origin, as well as the previous RAPD results of these accessions. The European rapeseed could be important germplasm resources for enriching the genetic background of Chinese rapeseed, and vice versa.
Background Acetolactate synthase (ALS)-inhibiting herbicide tribenuron-methyl (TBM) is an efficient gametocide that can cause rapeseed ( Brassica napus L.) to become male sterile and outcrossing. To find the reason the TBM treatment leads to male sterility, an integrated study using cytological, physiological, and transcriptomic methods was conducted. Results Some temporary symptoms, including the discoloration of young leaves and a short halt of raceme elongation, were observed in the rapeseed plants exposed to TBM at an application rate of 1 μg per plant. Both chloroplasts in young leaves and plastids in anthers were deformed. TBM also reduced the leaf photosynthetic rate and the contents of chlorophyll, soluble sugar and pyruvate. Both the tapetal cells and uni-nucleate microspores in the treated plants showed large autophagic vacuoles, and the tissue degenerated quickly. A transcriptomic comparison with the control identified 200 upregulated and 163 downregulated differential expression genes in the small flower buds of the TBM treatment. The genes encoding functionally important proteins, including glucan endo-1,3-beta-glucosidase A6, QUARTET3 (QRT3), ARABIDOPSIS ANTHER 7 (ATA7), non-specific lipid-transfer protein LTP11 and LTP12, histone-lysine N-methyltransferase ATXR6, spermidine coumaroyl-CoA acyltransferase (SCT), and photosystem II reaction centre protein psbB, were downregulated by TBM exposure. Some important genes encoding autophagy-related protein ATG8a and metabolic detoxification related proteins, including DTX1, DTX6, DTX35, cytosolic sulfotransferase SOT12, and six members of glutathione S-transferase, were upregulated. In addition, several genes related to hormone stimulus, such as 1-aminocyclopropane-1-carboxylate synthase 8 ( ACS8 ), ethylene-responsive factor ERF1A, ERF1, ERF71, CRF6, and RAP2-3 , were also upregulated. The transcriptional regulation is in accordance with the functional abnormalities of pollen wall formation, lipid metabolism, chloroplast structure, ethylene generation, cell cycle, and tissue autophagy. Conclusion The results suggested that except for ALS, the metabolic pathways related to lipid metabolism, pollen exine formation, photosynthesis and hormone response are associated with male sterility induced by TBM. The results provide new insight into the molecular mechanisms of inducing male sterility by sulfonylurea. Electronic supplementary material The online version of this article (10.1186/s12870-019-1722-1) contains supplementary material, which is available to authorized users.
Prior works either considered outage capacity of wireless video transmission systems but did not consider NOMA which is a key technology for 5G ultra-reliable low-latency (URLLC), or concerned the ergodic capacity of NOMA-OFDMA systems but did not consider the outage capacity emphasized in 5G URLLC scenario. In this paper, outage capacity (as well as ergodic capacity) maximization in a 5G URLLC scenario, are considered, using two proposed resource management schemes (i.e. B, C) and finally, proposed deep-learning-based versions of Schemes B and C (i.e. Schemes B' and C') to reduce the complexity and the latency for 5G URLLC. The proposed schemes re-allocate subcarrier according to outage capacityinstead of ergodic capacity only-maximization objective and choose the candidate user to gain subcarrier in a new way to improve the outage capacity. The numerical results show the proposed Scheme B and C increase the outage capacity (the percentage of satisfied users) from 79.2% for a prior work (Scheme A) to 85.2% and 92.6%, respectively. Scheme C also increases the ergodic capacity (average PSNR) from 34.7dB for Scheme A to 35.5dB. The deep learning based Schemes B' and C' perform slightly poorer than the corresponding non deep learning based Schemes B and C but the execution time/latency of Scheme B'/C' is less than Schemes B/C.
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