Genome-wide analysis and characterization of Aux/IAA family genes related to fruit ripening in papaya (Carica papaya L.).

BACKGROUND: Auxin/indole-3-acetic acid (Aux/IAA) family genes encode short-lived nuclear proteins that mediate the responses of auxin-related genes and are involved in several plant developmental and growth processes. However, how Aux/IAA genes function in the fruit development and ripening of papaya (Carica papaya L.) is largely unknown. RESULTS: In this study, a comprehensive identification and a distinctive expression analysis of 18 C. papaya Aux/IAA (CpIAA) genes were performed using newly updated papaya reference genome data. The Aux/IAA gene family in papaya is slightly smaller than that in Arabidopsis, but all of the phylogenetic subfamilies are represented. Most of the CpIAA genes are responsive to various phytohormones and expressed in a tissues-specific manner. To understand the putative biological functions of the CpIAA genes involved in fruit development and ripening, quantitative real-time PCR was used to test the expression profiling of CpIAA genes at different stages. Furthermore, an IAA treatment significantly delayed the ripening process in papaya fruit at the early stages. The expression changes of CpIAA genes in ACC and 1-MCP treatments suggested a crosstalk between auxin and ethylene during the fruit ripening process of papaya. CONCLUSIONS: Our study provided comprehensive information on the Aux/IAA family in papaya, including gene structures, phylogenetic relationships and expression profiles. The involvement of CpIAA gene expression changes in fruit development and ripening gives us an opportunity to understand the roles of auxin signaling in the maturation of papaya reproductive organs.

Transcriptome Analysis and Identification of Genes Associated with Floral Transition and Flower Development in Sugar Apple (Annona squamosa L.).

Sugar apple (Annona squamosa L.) is a semi-deciduous subtropical tree that progressively sheds its leaves in the spring. However, little information is available on the mechanism involved in flower developmental pattern. To gain a global perspective on the floral transition and flower development of sugar apple, cDNA libraries were prepared independently from inflorescent meristem and three flowering stages. Illumina sequencing generated 107,197,488 high quality reads that were assembled into 71,948 unigenes, with an average sequence length of 825.40 bp. Among the unigenes, various transcription factor families involved in floral transition and flower development were elucidated. Furthermore, a Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis revealed that unigenes exhibiting differential expressions were involved in various phytohormone signal transduction events and circadian rhythms. In addition, 147 unigenes exhibiting sequence similarities to known flowering-related genes from other plants were differentially expressed during flower development. The expression patterns of 20 selected genes were validated using quantitative-PCR. The expression data presented in our study is the most comprehensive dataset available for sugar apple so far and will serve as a resource for investigating the genetics of the flowering process in sugar apple and other Annona species.

Identification, Expression and IAA-Amide Synthetase Activity Analysis of Gretchen Hagen 3 in Papaya Fruit (Carica papaya L.) during Postharvest Process.

Auxin plays essential roles in plant development. Gretchen Hagen 3 (GH3) genes belong to a major auxin response gene family and GH3 proteins conjugate a range of acylsubstrates to alter the levels of hormones. Currently, the role of GH3 genes in postharvest physiological regulation of ripening and softening processes in papaya fruit is unclear. In this study, we identified seven CpGH3 genes in a papaya genome database. The CpGH3.1a, CpGH3.1b, CpGH3.5, CpGH3.6, and CpGH3.9 proteins were identified as indole-3-acetic acid (IAA)-specific amido synthetases. We analyzed the changes in IAA-amido synthetase activity using aspartate as a substrate for conjugation and found a large increase (over 5-fold) during the postharvest stages. Ascorbic acid (AsA) application can extend the shelf life of papaya fruit. Our data showed that AsA treatment regulates postharvest fruit maturation processes by promoting endogenous IAA levels. Our findings demonstrate the important role of GH3 genes in the regulation of auxin-associated postharvest physiology in papaya.

[Effect of oral cordarone in reversing persistent atrial fibrillation].

OBJECTIVE: To observe the efficacy and safety of oral cordarone dir reversing persistent atrial fibrillation (AF). METHODS; Eighty-two symptomatic chronic AF out-patients without history of acute diseases or severe hepatic/thyroid dysfunction were given oral cordarone at the loading dose of 200 mg thrice a day for 1-4 weeks followed by a twice-daily administration for another 1-4 weeks, with the maintenance dose of 200 or 100 mg once a day. The incidence of stroke and cardiac events and the mortality rate were compared between 43 patients with restored rhythm on cordarone and 39 patients on digoxin and/or betaloc for ventricular rhythm control. RESULTS: Among the 82 patients, sinus rhythm restoration was achieved in 43, with a successful rate of 52%. In 18 patients, the ejection fraction increased from (32+/-8)% to (46+/-10)%, left atrium diameter decreased from (4.6+/-1.1) cm to (4.1+/-0.8) cm. Except for slight T4 increase, QT prolongation and bradycardia in 3 cases, severe side effects were not observed in this study. Only one patient with restored sinus rhythm required rehospitalization after half a year for worsened heart failure, but in patients with controlled ventricular rhythm, 1 developed stroke, 1 experienced heart attack and 1 died of heart failure with bleeding. CONCLUSION: For patients with symptomatic reversible persistent AF, active treatment with cordarone can be convenient, effective and safe for sinus rhythm restoration.