Bioinformatic and expression analyses on carotenoid dioxygenase genes in fruit development and abiotic stress responses in <Emphasis Type="Italic">Fragaria vesca</Emphasis>

Carotenoid dioxygenases, including 9-cis-epoxycarotenoid dioxygenases (NCEDs) and carotenoid cleavage dioxygenases (CCDs), can selectively cleave carotenoids into various apocarotenoid products that play important roles in fleshy fruit development and abiotic stress response. In this study, we identified 12 carotenoid dioxygenase genes in diploid strawberry Fragaria vesca, and explored their evolution with orthologous genes from nine other species. Phylogenetic analyses suggested that the NCED and CCDL groups moderately expanded during their evolution, whereas gene numbers of the CCD1, CCD4, CCD7, and CCD8 groups maintained conserved. We characterized the expression profiles of FveNCED and FveCCD genes during flower and fruit development, and in response to several abiotic stresses. FveNCED1 expression positively responded to osmotic, cold, and heat stresses, whereas FveNCED2 was only induced under cold stress. In contrast, FveNCED2 was the unique gene highly and continuously increasing in receptacle during fruit ripening, which co-occurred with the increase in endogenous abscisic acid (ABA) content previously reported in octoploid strawberry. The differential expression patterns suggested that FveNCED1 and FveNCED2 were key genes for ABA biosynthesis in abiotic stress responses and fruit ripening, respectively. FveCCD1 exhibited the highest expression in most stages of flower and fruit development, while the other FveCCDs were expressed in a subset of stages and tissues. Our study suggests distinct functions of FveNCED and FveCCD genes in fruit development and stress responses and lays a foundation for future study to understand the roles of these genes and their metabolites, including ABA and other apocarotenoid products, in the growth and development of strawberry.     

Abscisic acid,sucrose, and auxin coordinately regulate berry ripening process of the Fujiminori grape

The aim of this study was to examine the effect of abscisic acid (ABA), sucrose, and auxin on grape fruit development and to assess the mechanism of these three factors on the grape fruit ripening process. Different concentrations of ABA, sucrose, and auxin were used to treat the grape fruit, and the ripening-related indices, such as physiological and molecular level parameters, were analyzed. The activity of BG protein activity was analyzed during the fruit development. Sucrose, ABA, and auxin influenced the grape fruit sugar accumulation in different ways, as well as the volatile compounds, anthocyanin content, and fruit firmness. ABA and sucrose induced, but auxin blocked, the ripening-related gene expression levels, such as softening genes PE, PG, PL, and CELL, anthocyanin genes DFR, CHI, F3H, GST, CHS, and UFGT, and aroma genes Ecar, QR, and EGS. ABA, sucrose, and glucose induced the fruit dry weight accumulation, and auxin mainly enhanced fruit dry weight through seed weight accumulation. In the early development of grape, starch was the main energy storage; in the later, it was glucose and fructose. Sucrose metabolism pathway-related gene expression levels were significant for glucose and fructose accumulation. BG protein activity was important in the regulation of grape ABA content levels. ABA plays a core role in the grape fruit development; sucrose functions in fruit development through two pathways: one was ABA dependent, the other ABA independent. Auxin blocked ABA accumulation to regulate the fruit development process.     

Functional Analysis of <Emphasis Type="Italic">VvBG1</Emphasis> During Fruit Development and Ripening of Grape

β-glucosidase (BG) was believed to take part in abscisic acid (ABA) synthesis via hydrolysis of ABA glucose ester to release active ABA during plant growth and development. However, there is no genetic evidence available to indicate the role of genes during fruit ripening. Here, the expression patterns of three genes (VvBG1, VvBG2, and VvBG3) encoding β-glucosidase were analyzed during grape fruit development, and it was found that β-glucosidase activity increased in grape fruit in response to various stresses. Furthermore, to verify the function of β-glucosidase during fruit ripening, heterogeneous expression of the VvBG1 gene in strawberry fruit was validated, and the results showed that the VvBG1 over-expression increased β-glucosidase and promoted the fruit ripening process in strawberry. In addition, we found that ABA contents increased in the VvBG1 over-expression of strawberry fruit, which induced fruit anthocyanin, soluble solid accumulation, and fruit softening. Moreover, genes related to coloring (CHS, CHI, F3H, and UFGT), softening (PG1, PL1, and EXP1), and aroma (SAAT, and QR) were up-regulated. This work will elucidate the specific roles of VvBGs in the synthesis of ABA and provide some new insights into the ABA-controlled grape ripening mechanism.     

Identification and expression analysis of the <Emphasis Type="Italic">Eucommia ulmoides</Emphasis> farnesyl diphosphate synthase gene family to reveal the key gene involved in rubber biosynthesis

Eucommia ulmoides Oliver is rich in trans-polyisoprene rubber (Eu-Rubber), a high-molecular mass polymer of isoprene units with a trans-configuration. Farnesyl diphosphate (FPP) synthase (FPS) is a key enzyme, which involved in the production of important precursors of different terpenoids. In this study, we cloned and characterized five novel FPS genes from E. ulmoides. The full-length synthases were named EuFPS1-5 and their deduced amino acid sequences exhibited high homology to those from other plant isoforms. EuFPS1 and EuFPS4 were observed to be highly expressed in leaves, EuFPS2 and EuFPS3 were present at low levels in leaves and fruit throughout the plant development, and EuFPS5 was highly expressed exclusively in young fruit. Expression of EuFPS5 correlated with the accumulation rate of Eu-Rubber and might be responsible for it. This study is expected to enhance our understanding of the role of EuFPSs in biosynthesis and regulation of useful secondary metabolites in E. ulmoides.     

Characterization of genes coding for galacturonosyltransferase-like (GATL) proteins in rice

In the present study, seven galacturonosyltransferase-like (GATL) genes (OsGATLs) in rice (Oryza sativa L.) were genome-widely identified and the chromosomal locations and the gene structures of which were characterized. Under normal condition, OsGATL2 and OsGATL3 are highly expressed in root, while OsGATL4 is highly expressed in stem and leaf. Many cis-elements related to stress response and plant hormone were found in the promoter sequence of each OsGATL. The expression patterns of these OsGATL genes under treatment with abscisic acid (ABA), drought and low temperature were assessed by qRT-PCR. The expression levels of most OsGATLs significantly increased following the treatments with drought or low temperature. In addition, physicochemical properties of OsGATLs and phylogenetic analysis with GATL from rice and several other species were performed. 3D structures and protein–protein interaction (PPI) network of OsGATLs were further predicted by Swiss-model and STRING 9.0 database, respectively. The identification and bioinformatic analysis of GATL family in rice could provide reference data for further study on their biological functions, especially in the responsiveness to hormones and stress signaling.     

<Emphasis Type="Italic">DORNRÖSCHEN-LIKE</Emphasis>, an AP2 gene,is necessary for stamen emergence in Arabidopsis

To identify novel genes in petal and stamen development, a genetic screen was carried out for enhancers of the unusual B class mutant pistillata-5 (pi-5). In pi-5 flowers, second whorl organs develop as sepals rather than petals, but third whorl stamens are normal. One pi-5 enhancer, dornröschen-like-2 (drnl-2), results in third whorl positions developing as filamentous organs. In addition to enhancing the pi-5 phenotype, drnl-2 mutants also exhibit a phenotype in a wild-type PI background. Although stamen primordia are morphologically visible during early stages of flower development, they fail to enlarge in drnl-2 mutants. DRNL, which encodes a single AP2 domain protein, is expressed in a dynamic pattern in the embryo, seedling, and flower. Analysis of both the drnl-2 mutant phenotype and the DRNL expression pattern in flowers suggests that DRNL plays a critical role in stamen emergence in Arabidopsis.