RNA interference is an important technology for gene functional research in many organisms. The pond wolf spider (Pardosa pseudoannulata) is an important natural enemy of rice field pests. To facilitate large‐scale gene functional research in this spider species and others, we developed an RNA interference (RNAi) method via ingestion of bacteria expressing dsRNA. The dsRNA targeting a cytochrome P450 monooxygenase (cyp41g2) was expressed in Escherichia coli HT115 (DE3). And then the bacterial suspension was fed to 14–20 days old spiderlings. The mRNA abundance of the target gene was significantly reduced after 3‐day's ingestion of bacteria expressing dsRNA, and between day 5 and 7, RNAi efficiency remained stable. Thus, we selected 5 days as the optimum interference time. Furthermore, the bacteria resuspension containing 20 ng/μl dsRNA was selected as the optimum concentration. To evaluate the applicability of this method, three other genes with different tissue expression pattern were also selected as targets. And the mRNA abundance of all the four target genes was significantly reduced with RNAi efficiency between 66.0% and up to 86.9%. The results demonstrated that the oral delivery of bacteria expressing dsRNA would be an effective RNAi method for the gene functional study in P. pseudoannulata.

27Rice yield is greatly reduced due to rice blast, a worldwide 28 multi-cycle fungal disease caused by the ascomycete Magnaporthe 29 oryzae. Previously, Bacillus cereus HS24 was isolated from rice growing 30 area, which showed a strong bio-control effect on M. oryzae. In order to 31 better exploit it as a bio-control agent, HS24 has been studied for its 32 mechanism of controlling rice blast. Our results showed that conidial 33 germination of M. oryzae was significantly inhibited by HS24 suspension, 34 and the inhibition rate reached to 97.83% at the concentration of 10 7 35 CFU/ml. The transcriptional level of CAMKII, PMC1 and CCH1, which 36 are key genes involved in Ca 2+ signaling pathway, were significantly 37 decreased in HS24-treated conidia. The treatment of M. oryzae with Ca 2+ 38 signaling pathway inhibitors KN-93, Verapamil, and cyclopiazonic acid 39 (CPA) significantly reduced conidial germination rate and inhibited germ 40 tube elongation. This inhibition effect was found to be 41 concentration-dependent, similar to the HS24 treatment. By quantifying 42 free Ca 2+ in M. oryzae conidia, a significant reduction of intracellular free 43 Ca 2+ concentration in HS24-treated conidia in comparison to sterile 44 water-treated conidia was found. The addition of exogenous Ca 2+ did not 45 abolish the inhibitory effect of HS24 on the reduction of intracellular free 46 Ca 2+ concentration and conidial germination. In conclusion, B. cereus 47 48 oryzae, and thus offers a great potential as a bio-control agent in rice blast 49 management. 50 51 Importance 52 In the bio-control of rice blast, most of researches focused on the 53 inhibitory effect of bio-control agents on development of M. oryzae, 54 including inhibition of conidia germination, germ tube deformity, 55 mycelium growth inhibition, etc, while little work has elucidated the 56 molecular mechanisms underlying the various phenotypic change in M. 57oryzae. In order to better exploit HS24 as a potential bio-control agent, 58 we studied the molecular mechanisms underlying the suppression of B. 59 cereus HS24 on M. oryzae Guy11, and draw the conclusion that HS24 60 may inhibit conidia germination and germ tube elongation through 61 inhibiting the Ca 2+ signaling pathway. In this study, we characterized the 62 morphological and physiological changes of M. oryzae when interacting 63 with B. cereus HS24, and further investgated the responses of M. oryzae 64 Ca 2+ signallig pathway to HS24 treatment. Thus we have provided one 65 more piece for the B. cereus / M. oryzae supression puzzle at the 66 molecular level. 67 68 of the world's population. However, rice yield is greatly reduced due to 71 rice blast, a worldwide multi-cycle fungal disease caused by the 72 ascomycete Magnaporthe oryzae (M. oryzae). Infection by the pathogen 73 is composed of a series of distinct processes (1). First, conidia adhere to 74 the rice epidermis, and then germinate to form germ tubes under suitable 75 environmental conditions. When the tips of germ tubes receive 76 hy...

ABSTRACT. In this study, the nitrate transporter gene CmNRT1 was isolated from the chrysanthemum variety 'Nannongxuefeng'. The full-length cDNA contains an open reading frame of 1761 bp encoding 587 residues. Using qRT-PCR, we found that CmNRT1 was induced by 10 mM NO 3 -in roots and shoots. Two Arabidopsis thaliana transgenic plants expressing CmNRT1 were selected for functional analyses. Root 15 N influx in wild-type and transgenic A. thaliana lines under 10 or 0.2 mM 15 NO 3 was tested. Our results indicate that CmNRT1 encodes a constitutive component for a lowaffinity transporter.

Rhizosphere microorganisms interact with plant roots by producing chemical signals to regulate root development. However, the involved distinct bioactive compounds and the signal transduction pathways are remaining to be identified. Here, we show that sesquiterpenes (SQTs) are the main volatile compounds produced by plant beneficial Trichoderma guizhouense NJAU 4742, inhibition of SQTs synthesis in this strain indicated their involvement in plant-fungus cross-kingdom signaling. SQTs component analysis further identified the cedrene, a high abundant SQT in strain NJAU 4742, could stimulate plant growth and root development. Genetic analysis and auxin transport inhibition showed that auxin receptor TIR1, AFB2, auxin-responsive protein IAA14, and transcription factor ARF7, ARF19 affect the response of lateral roots to cedrene. Moreover, auxin influx carrier AUX1, efflux carrier PIN2 were also indispensable for cedrene-induced lateral root formation. Confocal imaging showed that cedrene affected the expression of pPIN2:PIN2:GFP and pPIN3:PIN3:GFP, which may be related to the effect of cedrene on root morphology. These results suggest that a novel SQT molecule from plant beneficial T. guizhouense can regulate plant root development through auxin transport and signaling.

Detection of a mutation at codon 43 of the rpsL gene in Xanthomonas oryzae pv. oryzicola and X. oryzae pv. oryzae by PCR-RFLP ABSTRACT. The aim of this study was to develop a method to detect a point mutation in the ribosomal S12 protein (rpsL) gene in streptomycinresistant strains of Xanthomonas oryzae pv. oryzicola and X. oryzae pv. oryzae. The polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method was developed to detect a point mutation in codon 43 of the rpsL gene in X. oryzae pv. oryzicola and X. oryzae pv. oryzae. The 304-bp PCR product from the rpsL gene was digested by MboII to form two fragments (201 and 103 bp) if there was a mutation at codon 43, or three fragments (146, 103, and 55 bp) if there was no mutation. Compared with the results from nucleotide sequencing, the PCR-RFLP method was accurate in detecting the point mutation at codon 43 of the rpsL gene in streptomycin-resistant strains of X. oryzae pv. oryzicola and X. oryzae pv. oryzae. These results indicate that the PCR-RFLP is a simple, rapid and reliable method for detecting the point mutation at codon 43 of the rpsL gene.