Winter rape (Brassica napus L.) is better than other edible oil crops in China, but poor cold resistance is the key factor restricting its development. Hypocotyl length was found closely related to cold tolerance. The correlation between hypocotyl length and semi-lethal low temperature was significant, and the highest correlation between hypocotyl length and LT50 of autumn sowing was 0.9557. When the hypocotyl were treated at low temperature, the cells were seriously damaged and formed cavity structures, with cell walls seriously damaged or merged into each other. The positive regulation gene of hypocotyl length in resistant line of VHTSG 10 was identified as HY5 (transcription factor HY5-like) by qPCR, and bZIP transcription factor was found to be its conserved domain. Fused gene by GFP and HY5 from VHTSG 10 was transient transferred into Nicotiana benthamiana cells. Corresponding to the 35S:GFP widely distributed in plasma membrane of leaf epidermis, the fusion protein 35S:HY5-GFP was mainly distributed in nucleus. Thus we regarded BnHY5 gene is a key gene related to cold tolerance and hypocotyl length in B. napus.
Abstract Winter Brassica rapa is an important oilseed crop in northern China, but the mechanism of its cold resistance remains unclear. APX plays important roles in response of this plant to abiotic stress and in scavenging free radicals. In this study, 59 DEPs were isolated and identified from winter B. rapa and B. napus using bidirectional electrophoresis, and APX was found to be differentially expressed in these two species. Therefore, the roles of APX proteins in the cold response and superoxide metabolism pathways in both rapeseed species were further investigated. And comprehensive analysis of phylogeny, chromosome distribution, motif identification, sequence structure, gene duplication, and RNA-seq expression profile in APX gene family. Most of the BrAPX genes were specifically expressed under low temperature stress and behaved significantly differently in cold-tolerant and cold-sensitive varieties. qPCR was also used to verify the differences in expression between these two varieties under cold, freezing, drought and heat stress, and these candidate genes and proteins may play important roles in the response of B. rapa to low temperature stress and provide new information for the elucidation of the cold resistance mechanism in B. rapa .
In this paper, we report the assembly of reduced graphene oxide (RGO) and mesoporous silica grafted with alkyl chains (MSN-C18) to develop a new class of drug carriers which are able to deliver the loaded drug molecules into living cells upon exposure to near-infrared (NIR) light. This novel drug carrier consists of a structure formed by the noncovalent interaction of RGO caps and alkyl chains on the surface of MSN-C18. The capping of RGO sheets on mesoporous silica effectively blocks the pore mouths in the absence of NIR light. Conversely, and very importantly, the photothermal heating effect of RGO leads to a rapid increase in the local temperature upon exposure to NIR light, resulting in the weakening of the RGO sheet/alkyl chain noncovalent interaction. The RGO sheets will then be removed from the MSN surface, and the pores are uncapped. This uncapping mechanism makes it possible to release the loaded drug molecules upon irradiation with NIR light. In the present study, such a noncovalent assembly was examined by the use of doxorubicin as a model drug for NIR light-responsive intracellular controlled release studies. We believe that this noncovalent assembly will prove to be a promising drug delivery system for cancer therapy in the near future.
The flower development and differentiation of different cold resistance type winter rapeseeds were characterized using strong cold resistance cultivars Longyou 6,Tianyou 4 and 07-G01.Results showed that in Northwest cold arid regions flower differentiation of winter rapeseed began at-2 ℃ before winter and continued at-10 ℃ when flower differentiation came into the petal primordia and stamen primordium stages.When temperature dropped to-15 ℃ the differentiation slowed down or even stopped.Flower differentiation restarted in spring when temperature rose to-4 ℃ to 10 ℃,and developed faster with the rising temperature.The flower differentiation completed in ten days.It is also related to the cold resistance of a cultivar,for example,Longyou 6 is an ultra strong cold resistance cultivar,the flower differentiation started early and developed slowly;the flower differentiation of B.napus is later than that of B.rapus,it usually started until wheat turning green.Based on the research the flower bud differentiation of winter rapeseeds could be divided into three stages,ie initiation stage before winter,dormancy stage during winter and rapid development stage in spring.The third stage can be divided into seven short steps.
Winter Brassica rapa (B. rapa) is an important oilseed crop in northern China, but the mechanism of its cold resistance remains unclear. Ascorbate peroxidase (APX) plays important roles in the response of this plant to abiotic stress and in scavenging free radicals. In this study, the roles of APX proteins in the cold response and superoxide metabolism pathways in rapeseed species were investigated, and a comprehensive analysis of phylogeny, chromosome distribution, motif identification, sequence structure, gene duplication, and RNA-seq expression profiles in the APX gene family was conducted. Most BrAPX genes were specifically expressed under cold stress and behaved significantly differently in cold-tolerant and weakly cold-resistant varieties. Quantitative real-time-PCR (qRT-PCR) was also used to verify the differences in expression between these two varieties under cold, freezing, drought and heat stress. The expression of five BrAPX genes was significantly upregulated in growth cones at 3 h of cold stress, while their expression was significantly lower at 24 h than at 3 h. The expression of Bra015403 and Bra003918 was significantly higher in "Longyou-7" growth cones than in other treatments. Five BrAPXs (Bra035235, Bra003918, Bra033040, Bra017120, and Bra031934) were closely associated with abiotic stress responses in B. rapa. These candidate genes may play important roles in the response of B. rapa to low temperature stress and provide new information for the elucidation of the cold resistance mechanism in B. rapa.
Winter rapeseed (Brassica rapa L.) is an important overwintering oilseed crop that is widely planted in northwest China and suffers chronic low temperatures in winter. So the cold stress becomes one of the major constraints that limit its production. The currently existing genomes limit the understanding of the cold-tolerant genetic basis of rapeseed. Here we assembled a high-quality long-read genome of B. rapa "Longyou-7" cultivar, which has a cold-tolerant phenotype, and constructed a graph-based pan-genome to detect the structural variations within homologs of currently reported cold-tolerant related genes in the "Longyou-7" genome, which provides an additional elucidation of the cold-tolerant genetic basis of "Longyou-7" cultivar and promotes the development of cold-tolerant breeding in B. rapa.
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