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28 May 2016, Volume 23 Issue 3 Previous Issue    Next Issue
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Research Status and Prospect of Burkholderia glumae, the Pathogen Causing Bacterial Panicle Blight Zhou-qi Cui, Bo Zhu, Guan-lin Xie, Bin Li, Shi-wen Huang 2016, 23(3): 111-118.  DOI: 10.1016/j.rsci.2016.01.007 Abstract ( )   HTML ( )   PDF (379KB) ( )   Bacterial panicle blight caused by Burkholderia glumae is one of the most severe seed-borne bacterial diseases of rice in the world. Currently, this disease has affected many countries of Asia, Africa, South and North America. It is a typical example of the shifting from minor plant disease to major disease due to the changes of environmental conditions. Some virulent factors of B. glumae have been identified, including toxo?avins and lipases, whose productions are dependent on the TofI/TofR quorum-sensing system, and type III effectors. In spite of its economic significance, neither effective control measure for this disease nor resistant rice variety is currently available. In recent years, genomics, transcriptomics and other molecular methods have provided useful information for better understanding the molecular mechanisms underlying B. glumae virulence and the rice defence mechanisms against pathogens. For the prevention of this pathogen, our laboratory has developed a rapid and sensitive multiplex PCR assay for detecting and distinguishing B. glumae from other Burkholderia species. This improved understanding of B. glumae will shed new light on bacterial panicle blight disease management.

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Impact of Nitrogen, Phosphorus and Potassium on Brown Planthopper and Tolerance of Its Host Rice Plants Mamunur Rashid Md, Jahan Mahbuba, Shariful Islam Khandakar 2016, 23(3): 119-131.  DOI: 10.1016/j.rsci.2016.04.001 Abstract ( )   HTML ( )   PDF (758KB) ( )   The brown planthopper (BPH), Nilaparvata lugens (Stål), appeared as a devastating pest of rice in Asia. Experiments were conducted to study the effects of three nutrients, nitrogen (N), phosphorus (P) and potassium (K), on BPH and its host rice plants. Biochemical constituents of BPH and rice plants with varying nutrient levels at different growth stages, and changes in relative water content (RWC) of rice plants were determined in the laboratory. Feeding of BPH and the tolerance of rice plants to BPH with different nutrient levels were determined in the nethouse. Concentrations of N and P were found much higher in the BPH body than in its host rice plants, and this elemental mismatch is an inherent constraint on meeting nutritional requirements of BPH. Nitrogen was found as a more limiting element for BPH than other nutrients in rice plants. Application of N fertilizers to the rice plants increased the N concentrations both in rice plants and BPH while application of P and K fertilizers increased their concentrations in plant tissues only but not in BPH. Nitrogen application also increased the level of soluble proteins and decreased silicon content in rice plants, which resulted in increased feeding of BPH with sharp reduction of RWC in rice plants ultimately caused susceptible to the pest. P fertilization increased the concentration of P in rice plant tissues but not changed N, K, Si, free sugar and soluble protein contents, which indicated little importance of P to the feeding of BPH and tolerance of plant against BPH. K fertilization increased K content but reduced N, Si, free sugar and soluble protein contents in the plant tissues which resulted in the minimum reduction of RWC in rice plants after BPH feeding, thereby contributed to higher tolerance of rice plants to brown planthopper.

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Integration of Growing Milk Vetch in Winter and Reducing Nitrogen Fertilizer Application Can Improve Rice Yield in Double-Rice Cropping System Chun-huo Zhou, Zun-kang Zhao, Xiao-hua Pan, Shan Huang, Xue-ming Tan, Jian-fu Wu, Qing-hua Shi 2016, 23(3): 132-143.  DOI: 10.1016/j.rsci.2015.11.003 Abstract ( )   HTML ( )   PDF (707KB) ( )   To study whether integrative fertilization [growing milk vetch in winter and reducing the dose of chemical nitrogen (N) fertilizer] can improve rice yield, and to reveal the underlying regulatory mechanisms for integrative fertilization, a three-year field trial including two treatments, milk vetch-rice-rice (MRR) and winter fallow-rice-rice (FRR), was conducted in 2010, 2011 and 2012. Our results demonstrated that the MRR treatment could significantly improve rice yield compared with the FRR treatment, especially when the application ratio of milk vetch and chemical fertilizer was 1:2. MRR treatment increased the effective panicle number and the spikelet number per panicle. In addition, a higher tillering number, leaf area index, photosynthetic-potential and photosynthetic-potential to grain ratio were observed in MRR treatment, which could provide enough dry matter for yield formation. Moreover, in MRR treatment, we discovered a higher transportation ratio and transformation ratio of dry matter in culm and leaves, and a stronger total sink capacity and spikelet-root bleeding intensity at the heading stage and 15 d after heading. Furthermore, the MRR treatment showed higher total N, phosphorus and potassium uptakes than FRR treatment, which was associated with the higher root dry weight in each soil layers. These results suggest that growing milk vetch in winter can improve rice yield under less chemical N fertilizer application, which is due to the improvement of soil nutrient status and the increased of rice root growth and development.

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A Single-Tube, Functional Marker-Based Multiplex PCR Assay for Simultaneous Detection of Major Bacterial Blight Resistance Genes Xa21, xa13 and xa5 in Rice K. Hajira S., M. Sundaram R., S. Laha G., Yugander A., M. Balachandran S., C. Viraktamath B., Sujatha K., H. Balachiranjeevi C., Pranathi K., Anila M., Bhaskar S., Abhilash V., K. Mahadevaswamy H., Kousik M., Dilip Kumar T., Harika G., Rekha G. 2016, 23(3): 144-151.  DOI: 10.1016/j.rsci.2015.11.004 Abstract ( )   HTML ( )   PDF (470KB) ( )   In marker-assisted breeding for bacterial blight (BB) resistance in rice, three major resistance genes, viz., Xa21, xa13 and xa5, are routinely deployed either singly or in combinations. As efficient and functional markers are yet to be developed for xa13 and xa5, we have developed simple PCR-based functional markers for both the genes. For xa13, we designed a functional PCR-based marker, xa13-prom targeting the InDel polymorphism in the promoter of candidate gene Os8N3 located on chromosome 8 of rice. With respect to xa5, a multiplex-PCR based functional marker system, named xa5FM, consisting of two sets of primer pairs targeting the 2-bp functional nucleotide polymorphism in the exon II of the gene TFIIAɤ5 (candidate for xa5), has been developed. Both xa13-prom and xa5FM can differentiate the resistant and susceptible alleles for xa13 and xa5, respectively, in a co-dominant fashion. Using these two functional markers along with the already reported functional PCR-based marker for Xa21 (pTA248), we designed a single-tube multiplex PCR based assay for simultaneous detection of all the three major resistance genes and demonstrated the utility of the multiplex marker system in a segregating population.

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In Vitro Functional Study of Rice Adenosine 5'-Phosphosulfate Kinase De-zhen Wang, Guo-guo Chen, Lu-jia Lu, Zhao-jun Jiang, Yu-chun Rao, Mei-hao Sun 2016, 23(3): 152-159.  DOI: 10.1016/j.rsci.2016.04.002 Abstract ( )   HTML ( )   PDF (745KB) ( )   Sulfate can be activated by ATP sulfurylase and adenosine 5'-phosphosulfate kinase (APSK) in vivo. Recent studies suggested that APSK in Arabidopsis thaliana regulated the partition between APS reduction and phosphorylation and its activity can be modulated by cellular redox status. In order to study regulation of APSK in rice (OsAPSK), OsAPSK1 gene was cloned and its activity was analyzed. OsAPSK1 C36 and C69 were found to be the conserved counterparts of C86 and C119, which involved in disulfide formation in AtAPSK. C36A/C69A OsAPSK1 double mutation was made by site directed mutagenesis. OsAPSK1 and its mutant were prokaryotically over-expressed and purified, and then assayed for APS phosphorylation activity. OsAPSK1 activity was depressed by oxidized glutathione, while the activity of its mutant was not. Further studies in the case that oxidative stress will fluctuate in vivo 3'-phosphoadenosine-5'-phosphosulfate content, and all APSK isoenzymes have similar regulation patterns are necessary to be performed.

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Microsatellite-Aided Screening for Fertility Restoration Genes (Rf) Facilitates Hybrid Improvement El-Namaky Raafat, Sedeek Saber, Dea Moukoumbi Yonnelle, Ortiz Rodomiro, Manneh Baboucarr 2016, 23(3): 160-164.  DOI: 10.1016/j.rsci.2016.04.003 Abstract ( )   HTML ( )   PDF (343KB) ( )   DNA markers enabled to determine the chromosomal locations of the two Rf genes (Rf3 and Rf4) in the wild-abortive cytoplasmic male sterility (WA-CMS) system. Four simple sequence repeats (SSRs) RM171, RM258, RM315 and RM443 were used to detect the allelic status with respect to the fertility restoration genes (Rf3 and Rf4) in 300 rice cultivars or breeding lines. The results revealed that out of 300 lines, 90 lines screened had Rf3, 65 lines had Rf4, and 45 lines had Rf3 and Rf4 alleles. Furthermore, 45 lines selected using SSR markers were mated with a CMS line (IR58025A) to analyze their restoring ability. Offspring of all the test lines except HHZ8-SAL9DT1-Y1, HHZ5-SAL9-Y3-1 and IDSA77 exhibited higher pollen and spikelet fertility (> 80%), thus confirming they bear the Rf alleles. The hybrid offspring of ARH12-6-1-1-B-3-1, IR32307-10-3-2-1 and Sahel 329 had the highest pollen fertility (97.39%, 98.30% and 97.10%, respectively) and spikelet fertility (95.10%, 97.07% and 96.10%, respectively).