Boron homeostasis affects Longan yield: a study of NIP and BOR boron transporter of two cultivars.

BACKGROUND: Essential micronutrient Boron (B) plays crucial roles in plant survival and reproduction but becomes toxic in higher quantities. Although plant cells have different B transport systems, B homeostasis is mainly maintained by two transporter protein families: B exporters (BOR) and nodulin-26-like intrinsic proteins (NIP). Their diversity and differential expression are responsible for varied B tolerance among plant varieties and species. Longan is a highly admired subtropical fruit with a rising market in China and beyond. In the present study, we cultured Shixia (SX) and Yiduo (YD), two differently characterized Longan cultivars, with foliar B spray. We analyzed their leaf physiology, fruit setting, B content, and boron transporter gene expression of various tissue samples. We also traced some of these genes' subcellular localization and overexpression effects. RESULTS: YD and SX foliage share similar microstructures, except the mesophyll cell wall thickness is double in YD. The B spray differently influenced their cellular constituents and growth regulators. Gene expression analysis showed reduced BOR genes expression and NIP genes differential spatiotemporal expression. Using green fluorescent protein, two high-expressing NIPs, NIP1 and NIP19, were found to translocate in the transformed tobacco leaves' cell membrane. NIPs transformation of SX pollen was confirmed using magnetic beads and quantified using a fluorescence microscope and polymerase chain reaction. An increased seed-setting rate was observed when YD was pollinated using these pollens. Between the DlNIP1 and DlNIP19 transformed SX pollen, the former germinated better with increasing B concentrations and, compared to naturally pollinated plants, had a better seed-setting rate in YD♀ × SX♂. CONCLUSION: SX and YD Longan have different cell wall structures and react differently to foliar B spray, indicating distinct B tolerance and management. Two B transporter NIP genes were traced to localize in the plasma membrane. However, under high B concentrations, their differential expression resulted in differences in Jasmonic acid content, leading to differences in germination rate. Pollination of YD using these NIPs transformed SX pollen also showed NIP1 overexpression might overcome the unilateral cross incompatibility between YD♀ × SX♂ and can be used to increase Longan production.

Genome-wide identification of the longan R2R3-MYB gene family and its role in primary and lateral root.

R2R3-MYB is an important transcription factor family that regulates plant growth and development. Root development directly affects the absorption of water and nutrients by plants. Therefore, to understand the regulatory role of R2R3-MYB transcription factor family in root development of longan, this study identified the R2R3-MYB gene family members at the genome-wide level, and analyzed their phylogenetic characteristics, physical and chemical properties, gene structure, chromosome location and tissue expression. The analysis identified 124 R2R3-MYB family members in the longan genome. Phylogenetic analysis divided these members into 22 subfamilies, and the members of the unified subfamily had similar motifs and gene structures. The result of qRT-PCR showed that expression levels of DlMYB33, DlMYB34, DlMYB59, and DlMYB77 were significantly higher in main roots than in lateral as opposed to those of DlMYB35, DlMYB69, DlMYB70, and DlMYB83, which were significantly lower. SapBase database prediction and miRNAs sequencing results showed that 34 longan miRNAs could cleave R2R3-MYB, including 17 novel miRNAs unique to longan. The qRT-PCR and subcellular localization experiments of DlMYB92 and DlMYB98 showed that DlMYB92 is a key factor that regulates transcription in the nucleus and participates in the regulation of longan lateral root development. Longan also has a conserved miRNA-MYB-lateral root development regulation mechanism. This study provides a reference for further research on the transcriptional regulation of the miRNA-R2R3-MYB module in the root development of longan.

Metabolite and Transcriptome Profiles of Proanthocyanidin Biosynthesis in the Development of Litchi Fruit.

The fruit of Litchi chinensis contains high levels of proanthocyanidins (PAs) in the pericarp. These substances can serve as substrates of laccase-mediated rapid pericarp browning after the fruit is harvested. In this study, we found that the major PAs in litchi pericarp were (-)-epicatechin (EC) and several procyanidins (PCs), primarily PC A2, B2, and B1, and the EC and the PC content decreased with the development of the fruit. RNA-seq analysis showed that 43 early and late structure genes related to flavonoid/PA biosynthesis were expressed in the pericarp, including five ANTHOCYANIDIN REDUCTASE (ANR), two LEUCOANTHOCYANIDIN REDUCTASE (LAR), and two ANTHOCYANIDIN SYNTHASE (ANS) genes functioning in the PA biosynthesis branch of the flavonoid pathway. Among these nine PA biosynthesis-related genes, ANR1a, LAR1/2, and ANS1 were highly positively correlated with changes in the EC/PC content, suggesting that they are the key PA biosynthesis-related genes. Several transcription factor (TF) genes, including MYB, bHLH, WRKY, and AP2 family members, were found to be highly correlated with ANR1a, LAR1/2, and ANS1, and their relevant binding elements were detected in the promoters of these target genes, strongly suggesting that these TF genes may play regulatory roles in PA biosynthesis. In summary, this study identified the candidate key structure and regulatory genes in PA biosynthesis in litchi pericarp, which will assist in understanding the accumulation of high levels of browning-related PA substances in the pericarp.

Role of Transforming Growth Factor Beta in Peripheral Nerve Regeneration: Cellular and Molecular Mechanisms.

Peripheral nerve injury (PNI) is one of the most common concerns in trauma patients. Despite significant advances in repair surgeries, the outcome can still be unsatisfactory, resulting in morbidities such as loss of sensory or motor function and reduced quality of life. This highlights the need for more supportive strategies for nerve regrowth and adequate recovery. Multifunctional cytokine transforming growth factor-ß (TGF-ß) is essential for the development of the nervous system and is known for its neuroprotective functions. Accumulating evidence indicates its involvement in multiple cellular and molecular responses that are critical to peripheral nerve repair. Following PNI, TGF-ß is released at the site of injury where it can initiate a series of phenotypic changes in Schwann cells (SCs), modulate immune cells, activate neuronal intrinsic growth capacity, and regulate blood nerve barrier (BNB) permeability, thus enhancing the regeneration of the nerves. Notably, TGF-ß has already been applied experimentally in the treatment of PNI. These treatments with encouraging outcomes further demonstrate its regeneration-promoting capacity. Herein, we review the possible roles of TGF-ß in peripheral nerve regeneration and discuss the underlying mechanisms, thus providing new cues for better treatment of PNI.

[The student submission ways of experiment report based on digital microscopic system in parasitology teaching].

When the digital microscopy interactive system is applied to parasitology experiment teaching, students can submit their experiment reports in two ways: a paper document on a drawing paper or an electronic document taken images with the system. Submission of a paper report needs more time but requires the students to work more carefully, and an electronic document allows them to have more time to observe the specimen and work in a higher efficiency. It would be better to ask students to do both.

Laccase-Mediated Flavonoid Polymerization Leads to the Pericarp Browning of Litchi Fruit.

Litchi pericarp turns brown rapidly after fruit harvest, while the mechanism remains obscure. The contents of (-)-epicatechin (EC) and procyanidins (PCs) A2/B1/B2/C1 decreased during the pericarp browning, and a previously identified laccase (ADE/LAC) showed activity to these compounds, with brown products observed in the reactions. By UPLC-DAD-QTOF-MS/MS, isomers of dimeric, trimeric, and tetrameric PCs were detected in the EC-ADE/LAC reaction. In the presence of cyanidin-3-O-rutiside and rutin, anthocyanin-EC and rutin-EC adducts were, respectively, produced, and darker brown precipitation was observed in these reactions relatively to the EC-ADE/LAC reaction alone. ADE/LAC catalyzed the conversion of PC B2 to A-type PC dimers and B-type PC tetramers. ADE/LAC complemented the transparent testa of Arabidopsis LAC15-loss-of-function mutant (tt10) to wild-type dark brown seed coat. The results demonstrated that ADE/LAC-mediated flavonoid polymerization played an important role in the browning of pericarp.

Arabidopsis CHLOROPHYLLASE 1 protects young leaves from long-term photodamage by facilitating FtsH-mediated D1 degradation in photosystem II repair.

The proteolytic degradation of the photodamaged D1 core subunit during the photosystem II (PSII) repair cycle is well understood, but chlorophyll turnover during D1 degradation remains unclear. Here, we report that Arabidopsis thaliana CHLOROPHYLLASE 1 (CLH1) plays important roles in the PSII repair process. The abundance of CLH1 and CLH2 peaks in young leaves and is induced by high-light exposure. Seedlings of clh1 single and clh1-1/2-2 double mutants display increased photoinhibition after long-term high-light exposure, whereas seedlings overexpressing CLH1 have enhanced light tolerance compared with the wild type. CLH1 is localized in the developing chloroplasts of young leaves and associates with the PSII-dismantling complexes RCC1 and RC47, with a preference for the latter upon exposure to high light. Furthermore, degradation of damaged D1 protein is retarded in young clh1-1/2-2 leaves after 18-h high-light exposure but is rescued by the addition of recombinant CLH1 in vitro. Moreover, overexpression of CLH1 in a variegated mutant (var2-2) that lacks thylakoid protease FtsH2, with which CLH1 interacts, suppresses the variegation and restores D1 degradation. A var2-2 clh1-1/2-2 triple mutant shows more severe variegation and seedling death. Taken together, these results establish CLH1 as a long-sought chlorophyll dephytylation enzyme that is involved in PSII repair and functions in long-term adaptation of young leaves to high-light exposure by facilitating FtsH-mediated D1 degradation.

[In vitro effect of Huyinling extract on Trichomonas tenax].

The active ingredient of Huyinling, a combination of Chinese traditional medicine, was extracted by five different ethanol concentrations (40%-80%). There were seven groups named as five Huyinling ethanol extract groups (40%, 50%, 60%, 70%, and 80%), metronidazole group and blank control. Each Huyinling ethanol extract group was further divided into five subgroups with final concentration of 6.25, 12.5, 25, 50, and 100 mg/ml, respectively. Metronidazole group was given 10 microg/ml of the drug. Each group had 4 wells with 125 microl T. tenax(2 x 10(5)/ml). At 12 h, 24 h and 48 h after drug treatment, the anti-T. tenax effect of Huyinling ethanol extract was tested by microscope counting method. At 24 h the effect of Huyinling on T. tenax was examined with methyl thiazolyl tetrazolium (MTl) assay. The results showed that the higher concentration of Huyinling ethanol extract, the better effect on anti-T. tenax. 60% Huyinling ethanol extract group with concentrations of 6.25 mg/ml and 12.5 mg/ml showed higher anti-T. tenax effect than other groups (P < 0.01). The ethanol extract of Huyinling granules has a remarkable effect on T. tenax, and among the groups, 60% ethanol extract shows the best anti-T. tenax activity.

Bio-production of Baccatin III, an Important Precursor of Paclitaxel by a Cost-Effective Approach.

Natural production of anti-cancer drug taxol from Taxus has proved to be environmentally unsustainable and economically unfeasible. Currently, bioengineering the biosynthetic pathway of taxol is an attractive alternative production approach. 10-deacetylbaccatin III-10-O-acetyl transferase (DBAT) was previously characterized as an acyltransferase, using 10-deacetylbaccatin III (10-DAB) and acetyl CoA as natural substrates, to form baccatin III in the taxol biosynthesis. Here, we report that other than the natural acetyl CoA (Ac-CoA) substrate, DBAT can also utilize vinyl acetate (VA), which is commercially available at very low cost, acylate quickly and irreversibly, as acetyl donor in the acyl transfer reaction to produce baccatin III. Furthermore, mutants were prepared via a semi-rational design in this work. A double mutant, I43S/D390R was constructed to combine the positive effects of the different single mutations on catalytic activity, and its catalytic efficiency towards 10-DAB and VA was successfully improved by 3.30-fold, compared to that of wild-type DBAT, while 2.99-fold higher than the catalytic efficiency of WT DBAT towards 10-DAB and Ac-CoA. These findings can provide a promising economically and environmentally friendly method for exploring novel acyl donors to engineer natural product pathways.