The Fragaria vesca Homolog of SUPPRESSOR OF OVEREXPRESSION OF CONSTANS1 Represses Flowering and Promotes Vegetative Growth

In the annual long-day plant Arabidopsis thaliana, SUPPRESSOR OF OVEREXPRESSION OF CONSTANS1 (SOC1) integrates endogenous and environmental signals to promote flowering. We analyzed the function and regulation of the SOC1 homolog (Fragaria vesca [Fv] SOC1) in the perennial short-day plant woodland strawberry (Fragaria vesca). We found that Fv SOC1 overexpression represses flower initiation under inductive short days, whereas its silencing causes continuous flowering in both short days and noninductive long days, similar to mutants in the floral repressor Fv TERMINAL FLOWER1 (Fv TFL1). Molecular analysis of these transgenic lines revealed that Fv SOC1 activates Fv TFL1 in the shoot apex, leading to the repression of flowering in strawberry. In parallel, Fv SOC1 regulates the differentiation of axillary buds to runners or axillary leaf rosettes, probably through the activation of gibberellin biosynthetic genes. We also demonstrated that Fv SOC1 is regulated by photoperiod and Fv FLOWERING LOCUS T1, suggesting that it plays a central role in the photoperiodic control of both generative and vegetative growth in strawberry. In conclusion, we propose that Fv SOC1 is a signaling hub that regulates yearly cycles of vegetative and generative development through separate genetic pathways.     

Identification and functional characterization of SOC1-like genes in Pyrus bretschneideri

Flowering is a prerequisite for pear fruit production. Therefore, the development of flower buds and the control of flowering time are important for pear trees. However, the molecular mechanism of pear flowering is unclear. SOC1, a member of MADS-box family, is known as a flowering signal integrator in Arabidopsis. We identified eight SOC1-like genes in Pyrus bretschneideri and analyzed their basic information and expression patterns. Some pear SOC1-like genes were regulated by photoperiod in leaves. Moreover, the expression patterns were diverse during the development of pear flower buds. Two members of the pear SOC1-like genes, PbSOC1d and PbSOC1g, could lead to early flowering phenotype when overexpressed in Arabidopsis. PbSOC1d and PbSOC1g were identified as activators of the floral meristem identity genes AtAP1 and AtLFY and promote flowering time. These results suggest that PbSOC1d and PbSOC1g are promoters of flowering time and may be involved in flower bud development in pear.     

An acyl-CoA-binding protein from grape that is induced through ER stress confers morphological changes and disease resistance in Arabidopsis

We here report characterization of a grape (Vitis vinifera) acyl-CoA-binding protein (VvACBP). Expression of VvACBP was detected in grape leaves exposed to tunicamycin-induced endoplasmic reticulum (ER) stress as well as cold and heat shock treatments. In tendrils and peduncles, however, high-temperature treatment induced BiP (luminal binding protein) expression, a marker of ER stress in berry skin, but not VvACBP expression. We hypothesize that VvACBP may be sorted to the periphery of plant cells. Transgenic Arabidopsis plants, expressing VvACBP, exhibited slowed-down floral transition. The gene expression of proteins related to the photoperiodic pathway, CONSTANS, FLOWERING LOCUS T (FT), and SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1 (SOC1), was down-regulated in transgenic seedlings. These results underscore the possibility that VvACBP may affect the regulation of floral transition in Arabidopsis by suppressing the photoperiodic pathway. The transgenic Arabidopsis plants also exhibited morphological changes such as thicker inflorescences and rosette leaves. In addition, the rosette leaves of the transgenic plants had higher anthocyanin, total phenol, and chlorophyll contents than those of the control plants. Finally, the transgenic plants showed disease resistance to Pseudomonas syringae and Colletotrichum higginsianum, suggesting that VvACBP may also enhance disease resistance in grapevine.     

Over-expression of the Gerbera hybrida At-SOC1-like1 gene Gh-SOC1 leads to floral organ identity deterioration

Background and Aims

The family of MADS box genes is involved in a number of processes besides controlling floral development. In addition to supplying homeotic functions defined by the ABC model, they influence flowering time and transformation of vegetative meristem into inflorescence meristem, and have functions in roots and leaves. Three Gerbera hybrida At-SOC1-like genes (Gh-SOC1–Gh-SOC3) were identified among gerbera expressed sequence tags.

Methods

Evolutionary relationships between SOC1-like genes from gerbera and other plants were studied by phylogenetic analysis. The function of the gerbera gene Gh-SOC1 in gerbera floral development was studied using expression analysis, protein–protein interaction assays and reverse genetics. Transgenic gerbera lines over-expressing or downregulated for Gh-SOC1 were obtained using Agrobacterium transformation and investigated for their floral phenotype.

Key Results

Phylogenetic analysis revealed that the closest paralogues of At-SOC1 are Gh-SOC2 and Gh-SOC3. Gh-SOC1 is a more distantly related paralogue, grouping together with a number of other At-SOC1 paralogues from arabidopsis and other plant species. Gh-SOC1 is inflorescence abundant and no expression was seen in vegetative parts of the plant. Ectopic expression of Gh-SOC1 did not promote flowering, but disturbed the development of floral organs. The epidermal cells of ray flower petals appeared shorter and their shape was altered. The colour of ray flower petals differed from that of the wild-type petals by being darker red on the adaxial side and greenish on the abaxial surface. Several protein–protein interactions with other gerbera MADS domain proteins were identified.

Conclusions

The At-SOC1 paralogue in gerbera shows a floral abundant expression pattern. A late petal expression might indicate a role in the final stages of flower development. Over-expression of Gh-SOC1 led to partial loss of floral identity, but did not affect flowering time. Lines where Gh-SOC1 was downregulated did not show a phenotype. Several gerbera MADS domain proteins interacted with Gh-SOC1.     

Characterization of Chrysanthemum ClSOC1-1 and ClSOC1-2, homologous genes of SOC1

The MADS-box gene SOC1/TM3 (SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1/ Tomato MADS-box gene 3) is a main integrator in the Arabidopsis flowering pathway; its structure and function are highly conserved in many plant species. SOC1-like genes have been isolated in chrysanthemum, one of the most well-known ornamental plants, but it has not been well characterized thus far. We isolated and characterized ClSOC1-1 and ClSOC1-2, two putative orthologs of Arabidopsis SOC1, from the wild diploid chrysanthemum, Chrysanthemum lavandulifolium, to investigate the regulatory mechanisms of flowering time control in chrysanthemum. Expression analysis indicated that ClSOC1-1 and ClSOC1-2 were expressed in all examined organs/tissues (leaves, shoot apices, petioles, stems and roots) with different expression levels, and with high expression in the shoot apices and leaves during the early stage of floral transition. The expression levels of ClSOC1-1 and ClSOC1-2 in the shoot apices increased at different developmental stages with the highest expression levels after 7 days of short-day treatment. Overexpression of ClSOC1-1 and ClSOC1-2 in wild-type Arabidopsis resulted in early flowering, which was coupled with the upregulation of one of the flowering promoter genes LEAFY. Our results suggested that the ClSOC1-1 and ClSOC1-2 genes play an evolutionarily conserved role in promoting flowering in Chrysanthemum lavandulifolium and could serve as a vital target for the genetic manipulation of flowering time in the chrysanthemum.     

GSTM1, GSTT1, GSTP1, and GSTA1 genetic variants are not associated with coronary artery disease in Taiwan

Background and objective

The genetic variants of xenobiotic-metabolizing enzymes, such as those encoded by glutathione-S-transferase (GST) genes, may be associated with the risk of coronary artery disease (CAD). To investigate the genetic factors for CAD, we examined the GSTM1, GSTT1, GSTP1, and GSTA1 genotypes in a CAD cohort in Taiwan.

Methods

Our study included 458 CAD participants and 209 control participants who received coronary angiography to assess CAD. The severity of CAD was defined as the number of coronary vessels with 50% or greater stenosis. Sequence variation of the GSTM1 and GSTT1 genes was determined using a polymerase chain reaction (PCR). The GSTP1 (Ile105Val), and GSTA1 (-69C > T) genetic variants were identified using a combination of PCR and restriction fragment length polymorphism analysis. Logistic regression analysis was used to calculate the odds ratios (ORs) and 95% confidence intervals.

Results

Among the GST genetic variants examined, the GSTT1 null genotype was more prevalent in CAD participants with 3 stenosed vessels than in control participants (OR = 1.64, P = .02). This association was no longer observed after adjusting for age, sex, smoking, alcohol use, diabetes mellitus, and serum levels of total cholesterol and high-density lipoprotein cholesterol (OR = 1.28, P = .40). Both univariate and multivariate logistic regression analyses found no significant associations between CAD and the other genetic variants, either separately or in combination. In addition, no effects of interactions between the genotypes and environmental factors, such as cigarette smoking, were significantly associated with the risk of CAD.

Conclusion

The GST genetic variants examined were not associated with susceptibility to CAD in our Taiwanese cohort. This null association requires further confirmation with larger samples.     

Genetic polymorphisms of CYP2E1 and DNA repair genes HOGG1 and XRCC1: Association with hepatitis B related advanced liver disease and cancer

A population based case–control study was designed to explore the genetic risk factors for hepatitis B virus (HBV) related liver disease susceptibility. A total of 424 subjects comprising 210 controls, 50 acute HBV (AVH), 84 chronic HBV (CHBV), 25 HBV related cirrhosis and 55 HBV related hepatocellular carcinoma (HCC) cases were included in the study. PCR-RFLP was used for the genotyping of Cyp2E1*5B, hOGG1 codon 326 and XRCC1 codon 399. Compared to controls, Cyp2E1 rsaI variant c2 genotype increased the risk of HBV related liver disease severity by 2.68 fold, the highest for HCC cases (3.981 folds, p = 0.106); and was associated with higher histology activity index (HAI) (p < 0.001) in CHBV patients. Cyp2E1 and hOGG1 variants were independently associated with a significantly higher fibrosis score in CHBV group. Analysis of gene–gene interaction studies showed an increased risk of HCC, cirrhosis and CHBV in a Cyp2E1 variant + XRCC1 variant combination (p < 0.001); and hOGG1 variants + XRCC1 variants. A mutually independent heterozygous hOGG1 and XRCC1 combination resulted in a decreased risk of HBV related liver disease. On the other hand, a wild-type hOGG1 and XRCC1 combination was associated with a significantly higher risk of AVH (p = 0.010) but a lower risk of CHBV (p = 0.032) and HCC (p = 0.006). The gene–gene interactions were also associated with a significant increase in HAI and fibrosis score in CHBV patients. Cyp2E1, hOGG1 and XRCC1 genotypes significantly alter the risk of HBV related liver disease susceptibility and severity, independently or through gene–gene interaction.     

Virus-induced gene silencing of PEAM4 affects floral morphology by altering the expression pattern of PsSOC1a and PsPVP in pea

pea-MADS4 (PEAM4) regulates floral morphology in Pisum sativum L., however, its molecular mechanisms still remain unclear. Virus-induced gene silencing (VIGS) is a recently developed reverse genetic approach that facilities an easier and more rapid study of gene functions. In this study, the PEAM4 gene was effectively silenced by VIGS using a pea early browning virus (PEBV) in wild type pea JI992. The infected plants showed abnormal phenotypes, as the floral organs, especially the sepals and petals changed in both size and shape, which made the corolla less closed. The petals changed in morphology and internal symmetry with, the stamens reduced and carpel dehisced. Larger sepals and longer tendrils with small cauline leaves appeared, with some sepals turning into bracts, and secondary inflorescences with fused floral organs were formed, indicating a flower-to-inflorescence change. The infected plants also displayed a delayed and prolonged flowering time. The PEAM4-VIGS plants with altered floral morphology were similar to the pim (proliferating inflorescence meristem) mutant and also mimicked the phenotypes of ap1 mutants in Arabidopsis. The expression pattern of the homologous genes PsSOC1a and PsSVP, which were involved in flowering time and florescence morphological control downstream of PEAM4, were analyzed by real-time RT-PCR and mRNA in situ hybridization. PsSOC1a and PsSVP were ectopically expressed and enhanced in the floral meristems from PEAM4-silenced plants. Our data suggests that PEAM4 may have a similar molecular mechanism as AtAP1, which inhibits the expression of PsSOC1a and PsSVP in the floral meristem from the early stages of flower development. As such, in this way PEAM4 plays a crucial role in maintaining floral organ identity and flower development in pea.     

GSTM1 and GSTT1 gene polymorphisms as major risk factors for bronchopulmonary dysplasia in a Chinese Han population

Bronchopulmonary dysphasia (BPD) is a complex multifactorial disease with an obvious genetic predisposition. Oxidative stress plays an important role in its pathogenesis. Glutathione S-transferases (GSTs) detoxify metabolites produced by oxidative stress within the cell and protect the cells against injury. In the present study, the hypothesis that polymorphisms in the GSTM1 and GSTT1 genes are associated with BPD in Chinese Han infants was examined. Sixty infants with BPD and 100 gestational age and birth weight-matched preterm infants without BPD were recruited. Genotyping for GSTM1 and GSTT1 was performed by multiplex polymerase chain reaction (PCR). The GSTM1 null genotype was more prevalent in BPD infants (65.0%) than in the control subjects (48.0%), which yielded higher risk towards BPD (odds ratio (OR): 2.012, 95% confidence interval (CI) = 1.040–3.892, p = 0.037). There was no statistically significant association of GSTT1 genotype with BPD (OR: 1.691, 95% CI = 0.884–3.236, p = 0.111), although the frequency of GSTT1 null genotype was higher among the BPD subjects (60.0%) than in the control patients (47.0%). GSTM1 and GSTT1 double null genotype was also higher in BPD group (38.3%) than in controls (21.0%) with a higher risk towards BPD (OR: 2.338, 95%CI = 1.151–4.751, p = 0.017). The results suggest that null genotypes of GSTM1 and GSTT1 genes may contribute to the development of BPD in our Chinese Han population.     

新基因水稻 OsLSD1 的克隆及拟南芥和水稻类 LSD1 基因家族的生物信息学分析

类 LSD1 (LSD1-like) 基因家族是一类特殊的 C2C2 型锌指蛋白基因,编码植物特有的转录因子 . 目前已经研究的 2 个成员拟南芥 LSD1 (lesions stimulating disease resistance 1) 和 LOL1 (LSD-One-Like 1) 基因均参与植物细胞程序化死亡 (programmed cell death, PCD) 的调控 . 从水稻 cDNA 文库中克隆到 1 个类 LSD1 基因,命名为 OsLSD1. 该基因长 988 bp ,包含一个 432 bp 的开放阅读框,推导的氨基酸序列 (143 个氨基酸 ) 含有 3 个内部保守的锌指结构域 . DNA 印迹结果表明 OsLSD1 基因在水稻基因组中为单拷贝,且在根、茎和叶中表达 . 借助于生物信息学分析技术,从拟南芥和水稻数据库中各识别出 5 个和 7 个 ( 包括 OsLSD1) 类 LSD1 基因 . 分析了这些类 LSD1 基因的结构,蛋白质结构域组成 . 系统进化分析表明,无论基于编码区的核苷酸或氨基酸序列都可以将这些类 LSD1 基因分为 2 类 . 虽然不存在拟南芥或水稻特有的类 LSD1 蛋白,但有些结构域是水稻所特有的,也有些基因是来源于复制事件 .