Identification of genes associated with soluble sugar and organic acid accumulation in 'Huapi' kumquat (Fortunella crassifolia Swingle) via transcriptome analysis

BACKGROUND

The levels and ratios of sugar and acid are important contributors to fruit taste. Kumquat is one of the most economically important citrus crops, but information on the soluble sugar and organic acid metabolism in kumquat is limited. Here, two kumquat varieties - 'Rongan' (RA) and its mutant 'Huapi' (HP) - were used to assess soluble sugar and organic acid accumulation and the related genes.

RESULTS

Soluble sugars include sucrose, glucose and fructose, while malate, quinic acid and citrate are the dominant organic acids in the fruits of both kumquat varieties. HP accumulated more sugars but fewer organic acids than did RA. Transcriptome analysis revealed 63 and 40 differentially expressed genes involved in soluble sugar and organic acid accumulation, respectively. The genes associated with sugar synthesis and transport, including SUS, SPS, TST, STP and ERD6L, were up-regulated, whereas INVs, FRK and HXK genes related to sugar degradation were down-regulated in HP kumquat. For organic acids, the up-regulation of PEPC and NAD-MDH could accelerate malate accumulation. In contrast, high expression of NAD-IDH and GS resulted in citric acid degradation during HP fruit development. Additionally, the PK, PDH, PEPCK and FBPase genes responsible for the interconversion of soluble sugars and organic acids were also significantly altered in the early development stages in HP.

CONCLUSION

The high sugar accumulation in HP fruit was associated with up-regulation of SUS, SPS, TST, STP and ERD6L genes. The PEPCK, PEPC, NAD-MDH, NADP-IDH, GS and FBPase genes played important roles in acid synthesis and degradation in HP kumquat. These findings provide further insight into understanding the mechanisms underlying metabolism of sugars and organic acids in citrus. © 2021 Society of Chemical Industry.

Genome-Wide Identification of Long Non-coding RNA in Trifoliate Orange (Poncirus trifoliata (L.) Raf) Leaves in Response to Boron Deficiency

Long non-coding RNAs (lncRNAs) play important roles in plant growth and stress responses. As a dominant abiotic stress factor in soil, boron (B) deficiency stress has impacted the growth and development of citrus in the red soil region of southern China. In the present work, we performed a genome-wide identification and characterization of lncRNAs in response to B deficiency stress in the leaves of trifoliate orange (Poncirus trifoliata), an important rootstock of citrus. A total of 2101 unique lncRNAs and 24,534 mRNAs were predicted. Quantitative real-time polymerase chain reaction (qRT-PCR) experiments were performed for a total of 16 random mRNAs and lncRNAs to validate their existence and expression patterns. Expression profiling of the leaves of trifoliate orange under B deficiency stress identified 729 up-regulated and 721 down-regulated lncRNAs, and 8419 up-regulated and 8395 down-regulated mRNAs. Further analysis showed that a total of 84 differentially expressed lncRNAs (DELs) were up-regulated and 31 were down-regulated, where the number of up-regulated DELs was 2.71-fold that of down-regulated. A similar trend was also observed in differentially expressed mRNAs (DEMs, 4.21-fold). Functional annotation of these DEMs was performed using Gene Ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses, and the results demonstrated an enrichment of the categories of the biosynthesis of secondary metabolites (including phenylpropanoid biosynthesis/lignin biosynthesis), plant hormone signal transduction and the calcium signaling pathway. LncRNA target gene enrichment identified several target genes that were involved in plant hormones, and the expression of lncRNAs and their target genes was significantly influenced. Therefore, our results suggest that lncRNAs can regulate the metabolism and signal transduction of plant hormones, which play an important role in the responses of citrus plants to B deficiency stress. Co-expression network analysis indicated that 468 significantly differentially expressed genes may be potential targets of 90 lncRNAs, and a total of 838 matched lncRNA-mRNA pairs were identified. In summary, our data provides a rich resource of candidate lncRNAs and mRNAs, as well as their related pathways, thereby improving our understanding of the role of lncRNAs in response to B deficiency stress, and in symptom formation caused by B deficiency in the leaves of trifoliate orange.

Occupational Allergic Contact Dermatitis from Mioga (Zingiber Mioga Rosc.) in Greenhouse Cultivators

Mioga ( Zingiber mioga Rosc.) is a member of the ginger family (Zingiberaceae), which is native to tropical Asia. In Japan, the young flower buds are used as a spice, and hand dermatitis suspected as being an allergy to mioga has been recognized in mioga greenhouse cultivators. To investigate the extent of the problems and the causes of dermatitis, 20 householders cultivating mioga in their greenhouses were asked to participate in a questionnaire study. Consecutive patch tests were performed on some subjects with dermatitis. Self-reported questionnaires were distributed to the main cultivator in each household who attended a lecture of mioga cultivation methods held at an agriculture cooperative association in the area. Some subjects who answered as presenting or having had hand dermatitis were patch tested for mioga (as is), four kinds of mioga extracts, and three kinds of natural rubber gloves. Results: 35 cultivators from 16 households answered the questionnaire. Eight of the 35 subjects (22.9%) answered that they had experienced hand dermatitis since they started mioga cultivation. Four of the 8 subjects were patch tested. Two of the 4 subjects showed allergic reactions to mioga (as is) and the extracts. The other two cases showed irritation to mioga (as is). The first two cases also showed allergic reactions to natural rubber gloves. To our knowledge, there is no previous report of allergic contact dermatitis from mioga.

Subjective Symptoms of Medical Students Exposed to Formaldehyde during a Gross Anatomy Dissection Course

The purpose of this study is to investigate the safety of and to try to find the best plan to cope with exposure to FA for students during a gross anatomy dissection course. The FA exposure level and subjective symptoms was estimated. The relationship between exposure to FA and subjective symptoms of irritation were discussed for times; before, in the beginning period, in the middle period, and upon completion of the Anatomy Dissection Course. The geometric means of FA concentration were 32.7 ug/m3 (before), 891.3 ug/m3 (beginning), 763.3 ug/m3 (middle), and 238.9 ug/m3 (completion), respectively. Among them, FA-related symptoms were observed in 61.1%; 28.0% fell strong stress during the course, and 27.4% complained that their normal life situation was affected. Our results indicate that such subjective symptoms during the anatomy dissection course were related to the period spent in the anatomy dissection room. Our study suggests that shortening the time of each anatomy dissection practical class and reduction of the number of cadaver tables could help to reduce symptoms.

Transcription profiles of boron-deficiency-responsive genes in citrus rootstock root by suppression subtractive hybridization and cDNA microarray

Boron (B) deficiency has seriously negative effect on citrus production. Carrizo citrange (CC) has been reported as a B-deficiency tolerant rootstock. However, the molecular mechanism of its B-deficiency tolerance remained not well-explored. To understand the molecular basis of citrus rootstock to B-deficiency, suppression subtractive hybridization (SSH) and microarray approaches were combined to identify the potential important or novel genes responsive to B-deficiency. Firstly four SSH libraries were constructed for the root tissue of two citrus rootstocks CC and Trifoliate orange (TO) to compare B-deficiency treated and non-treated plants. Then 7680 clones from these SSH libraries were used to construct a cDNA array and microarray analysis was carried out to verify the expression changes of these clones upon B-deficiency treatment at various time points compared to the corresponding controls. A total of 139 unigenes that were differentially expressed upon B-deficiency stress either in CC or TO were identified from microarray analysis, some of these genes have not previously been reported to be associated with B-deficiency stress. In this work, several genes involved in cell wall metabolism and transmembrane transport were identified to be highly regulated under B-deficiency stress, and a total of 23 metabolic pathways were affected by B-deficiency, especially the lignin biosynthesis pathway, nitrogen metabolism, and glycolytic pathway. All these results indicated that CC was more tolerant than TO to B-deficiency stress. The B-deficiency responsive genes identified in this study could provide further information for understanding the mechanisms of B-deficiency tolerance in citrus.

Digital gene expression analysis of corky split vein caused by boron deficiency in 'Newhall' Navel Orange (Citrus sinensis Osbeck) for selecting differentially expressed genes related to vascular hypertrophy

Corky split vein caused by boron (B) deficiency in 'Newhall' Navel Orange was studied in the present research. The boron-deficient citrus exhibited a symptom of corky split vein in mature leaves. Morphologic and anatomical surveys at four representative phases of corky split veins showed that the symptom was the result of vascular hypertrophy. Digital gene expression (DGE) analysis was performed based on the Illumina HiSeq™ 2000 platform, which was applied to analyze the gene expression profilings of corky split veins at four morphologic phases. Over 5.3 million clean reads per library were successfully mapped to the reference database and more than 22897 mapped genes per library were simultaneously obtained. Analysis of the differentially expressed genes (DEGs) revealed that the expressions of genes associated with cytokinin signal transduction, cell division, vascular development, lignin biosynthesis and photosynthesis in corky split veins were all affected. The expressions of WOL and ARR12 involved in the cytokinin signal transduction pathway were up-regulated at 1(st) phase of corky split vein development. Furthermore, the expressions of some cell cycle genes, CYCs and CDKB, and vascular development genes, WOX4 and VND7, were up-regulated at the following 2(nd) and 3(rd) phases. These findings indicated that the cytokinin signal transduction pathway may play a role in initiating symptom observed in our study.

An epidemiological survey of low back pain and axial spondyloarthritis in a Chinese Han population

OBJECTIVE

To investigate the prevalence of low back pain (LBP) and axial spondyloarthritis (SpA) in a Chinese Han population.

METHODS

A face-to-face investigation was performed in the Han population of Dalang Town, Yangshan County, Guangdong Province, China, using a questionnaire established in France in 1999. First the clinical features associated with SpA were investigated, then the human leucocyte antigen (HLA)-B27 and sacroiliac joint radiographic examinations were carried out. Finally, the diagnosis of SpA was determined by rheumatologists.

RESULTS

A total of 13 315 subjects participated in the study and 10 921 were aged >16 years; of these, 787 (7.21%) had LBP. There were 92 axial SpA patients (0.782% in subjects >16 years old and 11.96% in subjects with LBP). There were 29 (0.253%) cases of ankylosing spondylitis (AS), 60 (0.507%) undifferentiated axial SpA (USpA), and three (0.022%) psoriatic arthritis (PsA). Patients in the SpA groups had higher percentages in onset <40 years, insidious onset, morning stiffness, and affected for >3 months compared with those in other LBP groups. Simultaneous symptoms associated with spondylitis, such as buttock pain, heel pain, psoriasis, and SpA family history, were more commonly present. Of the axial SpA patients, 82.67% were HLA-B27 positive, clearly a greater percentage than those (11.65%) in other LBP groups.

CONCLUSIONS

The survey questionnaire for SpA in this study is useful for axial SpA screening in China. In southern China, the prevalence of LBP is 7.21%. The prevalence of axial SpA is 0.782%. USpA is the most common subtype of SpA, followed by AS.

Association of IL-1 gene complex members with ankylosing spondylitis in Chinese Han population

There are reports of IL-1 complex gene polymorphisms in ankylosing spondylitis (AS; MIM 106300), but the results have been inconsistent among populations. Moreover, few studies examine the association between IL-1 complex gene polymorphisms and clinical symptoms of AS patients. We investigated polymorphisms of IL-1 complex with AS in the Chinese Han population in this study. Chinese Han AS patients and ethnically matched healthy controls were genotyped for five single nucleotide polymorphisms (IL1beta+3953, beta-511, F10.3, RN.4, RN.6/1) and the IL1RN.VNTR of IL-1 gene cluster. Allele, Genotype and haplotype frequencies were compared between cases and controls by SHEsis software. The frequency of allele C of the marker IL1F10.3 was significantly increased in AS patients versus controls [p = 0.001, odds ratio (OR) = 1.54, 95% confidence interval (CI) = 1.19-1.20; p = 0.002, respectively]. Strong linkage disequilibrium was identified between IL1B-511, IL1B+3953 and RN4 in both patients and healthy controls (D' > 0.95). Haplotypes of pairs of these markers (6) were also significantly associated with AS. The strongest associations observed was between allele combination B-511-T/B+3953-C/F10.3-C/RN4-T/RN2VNTR-1/RN6.1-C and AS (p = 3.32 x 10(-5), OR = 4.41, 95% CI=2.1-9.3). Clinical manifestation showed week association between RN2VNTR A2 allele and risk of peripheral arthritis (OR = 0.2, 95% CI = 0.07-0.91). The IL-1 gene cluster is associated with AS in Chinese population. This finding provides strong statistical support for the previously observed relationship and indicates possible association between clinical manifestation and genetic factor.