Characterization and functional analysis of an α-adrenergic-like octopamine receptor in the small brown planthopper Laodelphax striatellus.

As an important biogenic amine in invertebrates and corresponding to the neurotransmitter norepinephrine in vertebrates, octopamine (OA) regulates diverse physiological and behavioral processes by binding to specific octopamine receptors (OARs) in invertebrates. At present, OARs have been identified and characterized in several insects. However, less is known about the OARs of Laodelphax striatellus, one of the most destructive pests in East Asian rice fields. In the present study, an α1-adrenergic-like OAR (LsOA1) from L. striatellus was cloned. LsOA1 has the typical characteristics of G-protein coupled receptors and is clustered with other insect homologs. The transcript level of LsOA1 varied in various stages and tissues, and was highly expressed at the egg stage and in the brain. Silencing of LsOA1 causes a reduction in vitellogenin (LsVg) and vitellogenin receptor (LsVgR) expression. Although LsOA1 interference did not affect the fecundity and survival of L. striatellus, the hatching rate of L. striatellus was significantly reduced, and the hatching period was prolonged. The decrease in the amount of honeydew excreted after silencing LsOA1 indicates that LsOA1 may be involved in regulating the feeding behavior of L. striatellus. In addition, the interference of LsOA1 significantly reduced the expression of capsid protein (CP) and viral RNA3 segment (RNA3) in rice stripe virus (RSV)-viruliferous L. striatellus, but did not affect the vertical transmission rate of RSV. The present study demonstrated that LsOA1 played a crucial role in the physiological and behavioral processes of L. striatellus, which will provide the basis for developing a new target gene for pest control.

BZR proteins: identification, evolutionary and expression analysis under various exogenous growth regulators in plants.

BACKGROUNDS: The BRASSINAZOLE-RESISTANT (BZR) family of transcription factors affects a variety of developmental and physiological processes and plays a key role in multiple stress-resistance functions in plants. However, the evolutionary relationship and individual expression patterns of the BZR genes are unknown in various crop plants. METHODS AND RESULTS: In this study, we performed a genome-wide analysis of the BZR genes family in wheat and rice. Here, we found a total of 16 and 6 proteins containing the BZR domain in wheat and rice respectively. The phylogenetic analysis divided the identified BZR proteins from several plants into five subfamilies. The intron/exon structural patterns and conserved motifs distribution revealed that BZR proteins exhibite high specificities in each subfamily. Moreover, the co-expression and protein-protein interaction analysis suggested that BZR proteins may interact/co-expressed with several other proteins to perform various functions in plants. The presence of different stresses, hormones and light-responsive cis-elements in promoter regions of BZR genes imply its diverse functions in plants. The expression patterns indicated that many BZR genes regulate organ development and differentiation. BZR genes significantly respond to exogenous application of brassinosteroids, melatonin and abiotic stresses, demonstrating its key role in various developmental and physiological processes. CONCLUSION: The present study establishes the foundation for future functional genomics studies of BZR genes through reverse genetics and to further explore the potential of BZR genes in mitigating the stress tolerance in crop plants.

Decoyinine Induced Resistance in Rice against Small Brown Planthopper Laodelphax striatellus.

Induced resistance against SBPH via microbial pesticides is considered as an eco-friendly and promising management approach. In this study, the induced resistance against SBPH in rice seedling by a new potential microbial pesticide, decoyinine (DCY), a secondary metabolite produced by Streptomyces hygroscopicus, was evaluated to investigate the effects of DCY on SBPH's biological and population parameters along with defense-related physiological and biochemical indices in rice against SBPH feeding. We found that DCY has potential to improve rice resistance and significantly reduced the fecundity of SBPH. Laboratory results revealed that DCY treated rice significantly changed SBPH's fecundity and population life table parameters. The concentrations of hydrogen peroxide (H2O2), soluble sugars and malondialdehyde (MDA) were significantly lower in DCY treated rice plants against SBPH infestation at 24, 48 and 96 hours post infestation (hpi), respectively. The concentrations of antioxidant enzymes, catalase (CAT) was significantly higher at 72 hpi, while super oxidase dismutase (SOD) and peroxidase (POD) concentrations were recorded higher at 96 hpi. The concentrations of synthases enzymes, phenyl alanine ammonia-lyase (PAL) was higher at 48 hpi, whereas polyphenol oxidase (PPO) concentration was maximum at 72 hpi against SBPH infestation. The results imply that DCY has unique properties to enhance rice resistance against SBPH by stimulating plant defensive responses. Microbial pesticides may be developed as an alternative to chemical pest control.

The Homeodomain-Leucine Zipper Genes Family Regulates the Jinggangmycin Mediated Immune Response of Oryza sativa to Nilaparvata lugens, and Laodelphax striatellus.

The homeodomain-leucine zipper (HDZIP) is an important transcription factor family, instrumental not only in growth but in finetuning plant responses to environmental adversaries. Despite the plethora of literature available, the role of HDZIP genes under chewing and sucking insects remains elusive. Herein, we identified 40 OsHDZIP genes from the rice genome database. The evolutionary relationship, gene structure, conserved motifs, and chemical properties highlight the key aspects of OsHDZIP genes in rice. The OsHDZIP family is divided into a further four subfamilies (i.e., HDZIP I, HDZIP II, HDZIP III, and HDZIP IV). Moreover, the protein-protein interaction and Gene Ontology (GO) analysis showed that OsHDZIP genes regulate plant growth and response to various environmental stimuli. Various microRNA (miRNA) families targeted HDZIP III subfamily genes. The microarray data analysis showed that OsHDZIP was expressed in almost all tested tissues. Additionally, the differential expression patterns of the OsHDZIP genes were found under salinity stress and hormonal treatments, whereas under brown planthopper (BPH), striped stem borer (SSB), and rice leaf folder (RLF), only OsHDZIP3, OsHDZIP4, OsHDZIP40, OsHDZIP10, and OsHDZIP20 displayed expression. The qRT-PCR analysis further validated the expression of OsHDZIP20, OsHDZIP40, and OsHDZIP10 under BPH, small brown planthopper (SBPH) infestations, and jinggangmycin (JGM) spraying applications. Our results provide detailed knowledge of the OsHDZIP gene family resistance in rice plants and will facilitate the development of stress-resilient cultivars, particularly against chewing and sucking insect pests.