Bph-gene

Name: Arghya Narendra DianastyaID: 5620000087Departement: Agronomy (undergraduate student)Subject: Introduction to Agricultural Molecular Genetics

ASSIGNMENTHow to Study Bph Resistance Gene

Brown PlanthopperBrown planthopper causes direct damage to the plant by sucking the phloem sap, feeds by phloem abstraction. High BPH populations can destroy a plant in a short period of time, Large number of plants become brown and dry. The condition is called hopperburn. Even if the planthopper population is not high enough to kill the plants, BPH feeding may consi-derably reduce yields. BPH can consume more than 28% of the total dry matter of rice plants infested at reproductive stage. BPH also transmits serious viral diseases, such as grassy stunt and ragged stunt virus (Harini et. al., 2013).Farmers used to chemical method for controlling this insect, which are expensive and harmful to the environment. The most economical and environment-friendly strategy to control this insect is to grow genetically resistant rice varieties (Jena and Kim, 2010).

BPH Resistance GeneIn 1991, only four BPH biotypes are known. Biotypes 1 and 2 are widely distributed in Southeast Asia, biotype 3 is a laboratory biotype produced in the Philippines, and biotype 4 occurs in the Indian subcontinent (Khush and Brar, 1991). Until 2013, 25 BPH resistance genes have been identified from cultivated and wild species of Oryza. Nineteen of the 25 resistance genes have been mapped to six chromosome (Jun et. al., 2012). Bph14 is the first and only cloned insect resistance gene so far in rice (Lei et. al. 2013).

(Bph genes in rice species)

Understanding Rice Plant Resistance to The Brown PlanthopperAccording to Wei et. al. (2009), there are many proteins involved in multiple pathways showed significant changes in expression in response to BPH, This includes jasmonic acid synthesis proteins, oxidative stress response proteins, beta-glucanases, protein; kinases, clathrin protein, glycine cleavage system protein, photosynthesis proteins and aquaporins. Planthopper attack causes a suite of responses in the rice plant, some of which ultimately lead to symptoms of hopper burn. Many of these responses, in both resistant and susceptible varieties, involve differential gene regulation related to such diverse functions as metabolism, energy, cell-cycle and DNA processing, transcription, protein synthesis, cellular transport, development, biogenesis of cellular components, subcellular localization and starch breakdown. Plants infested by BPH also emit inducible volatiles that are not detected in healthy or mechanically damaged plants (Horgan, 2009).Attack-related elicitors, such as -glucosidase, present in the saliva of BPH, have been linked to salicyclic acid (SA), hydrogen peroxide, and ethylene production. Ethylene eventually can induce the expression of the OsBi1 gene (O. sativa BPH-induced gene of unknown function), particularly in tissues around the bundle sheath, including vascular tissue, stomium, and tapetum of rice stems (Horgan, 2009).

Identification of BPH Resistance Gene in Rice1. Wild Rice SelectionWild rice selection for BPH resistance gene has to be done to find the resistance gene. An example of wild rice selection is in Li et. al. (2006) journal. In that journal, more than 1 200 accessions of common wild rice (Oryza rufipogon Griff.) were evaluated for the resistance to several biotypes of BPH. 30 resistant accessions were obtained and 6 of them showed broad spectrum resistance to 5 or all of the 6 BPH biotypes, i.e. biotypes 1 and 2, Bangladesh, Mekong (Vietnam), Cuulong (Vietnam) and Pantnagar (India), which are spreading most rice growing regions in the world.

2. Introgression BPH Resistance from Wild RiceDevelopment of resistant rice cultivars through host plant resistance is generally considered to be the most economic and effective way for controlling BPH damage (Harini et. al., 2013).

3. Resistance EvaluationThere are many method to evaluate of BPH resistance gene. Some of the method is the Tiller Seedbox Screening Technique (TSST). According to Wang et. al. (2011), the example of TSST method are: First, the seeds of B5, TN1 and each F2 plant were separately sown in the fields. When the seedlings had 3 4 tillers,separated one tiller from each F2 plant and two parents, and replanted them in plastic pods. In each plastic pod 8 tillers were planted, 6 of them from the F2 individuals and the other two from the B5 and TN1, planted along a cycle. About a week later, when the replanted tillers were alive and grew well, the tillers were infested with 4th instar nymphs of the BPH at the density of 15 insects per tiller, 120 insects per pot. 24 hours after the infestation, recorded the proportion of BPH distribution among the F2 individuals and the parents. Then let the insects feed, mate, lay eggs and hatch freely. Until TN1, the susceptible parent, died, evaluated the severity scores of each F2 plant. The digested DNA fragments were transferred to nylon membrane and hybridized. Five restriction enzymes, including EcoR, EcoR, Hind , BamH, and Dra, were used for the survey of parental polymorphism.

4. Molecular Marker AnalysisMolecular markers have demonstrated a potential to detect genetic diversity and relatedness of most crop species and to aid the management of plant genetic resources. In contrast to morphological traits, molecular markers can reveal differences among geno-types at DNA level, providing a more direct, reliable and efficient tool for germplasm characterization, conservation and management (Harini et. al., 2013).To get the BPH resistance gene, it can be conducted by genetic marker. A genetic marker is a gene or DNA sequence with a known location on a chromosome that can be used to identify individuals or species. Among all DNA markers microsatellites are codominant in nature; show high allelic diversity; are easily and economically assayed by PCR and can be automated. Many potential SSR markers have been identified in rice and over 25,000 have been developed as molecular markers (Harini et. al., 2013).The chromosomal location of the BPH resistance gene provides the foundation of manipulating the gene. In order to identify DNA markers linked to the BPH resistance it can be employed by bulked segregant analysis with SSR (simple sequence repeat) technique. SSR makers are widely distributed in the rice genome and can be easily and economically analyzed by polymerase chain reaction. SSR can detect high allelic variation and provide a new tool for gene mapping and marker-assisted selection (MAS) in rice (Yang et. al. 2002).

5. Mapping BPH resistance Gene

Obviously, localizing the BPH resistance genes is the base of using them efficiently. Some scientist mapped Bph1 and bph2 on chromosome 4, Bph3 and bph4 on chromosome 3 using trisomic analysis. The development of molecular markers facilitated the construction of genetic linkage maps, which make mapping easier, faster and more accurate than before. Recently some resistance genes have been mapped using the molecular marker analysis. The Bph1 and bph2 were remapped on chromosome 12, and Bph(10) was also mapped on chromosome (Wang et. al., 2001).

6. QTL for BPH ResistanceAccording to Santhanalakshmi et. al. (2009), About 22 major genes and several QTLs associated with BPH resistance have been identified and mapped on the rice chromosome. Quantitative Trait Loci that confer BPH resistance have also been found in certain Indica Cultivars such as B5 and Col. 5 (Thailand).

REFERENCE

Jena K.K, S.M. Kim, Rice. 2010. 3: 161-171.

Jun He Yuqiang Liu Yanling Liu Ling Jiang Han Wu Haiyan Kang Shijia Liu Liangming Chen Xi Liu Xianian Cheng Jianmin Wan. 2012. High-resolution mapping of brown planthopper (BPH) resistance gene Bph27(t) in rice (Oryza sativa L.) Received: 13 February 2012 / Accepted: 9 November 2012 / Published online: 24 November 2012 _ Springer Science+Business Media Dordrecht.

Harini S.A., Sai Kumar S., Padma Balaravi, Richa Sharma, Ayyappa Dass M., and Vinay Shenoy. 2013. Evaluation of rice genotypes for brown planthopper (BPH) resistance using molecular markers and phenotypic methods. Afr. J. Biotechnol 12(19) : 2515-2523.

Horgan F. 2009. Mechanisms of resistance: a major gap in understanding planthopper-rice interactions. Pp 281-302 IN Heong KL, Hardy B, editors. 2009. Planthoppers: new threats to the sustainability of intensive rice production systems in Asia. Los Baos (Philippines).

Khush G. S. and D. S. Brar, 1991. Genetics of resistance to insect in crop plant. Adv. Agron. 45 : 223- 274.Li et al 2006, The Evaluation and Utilization of New Genes for Brown Planthopper Resistance in Common Wild Rice (Oryza rufipogon Griff.), Molecular Plant Breeding, 4(3): 365-371.

Santhalakhsmi et.al. 2009. Mapping Genetic Locus Linked to Brown Planthopper Resistance in Rice. International Journal of Plant Breeding and Genetics. https://www.academia.edu/763898/.Wang Buna, Huang Zhen, Shu Lihui, Ren Xiang, Li Xianghua & He Guangcun. 2001. Mapping of two new brown planthopper resistance genes from wild rice. Chinese Science Bulletin Vol. 46 No. 1. Wei Z, Hu W, Lin Q, Cheng X, Tong M, Zhu L, Chen R, He G. 2009. Understanding rice plant resistance to the Brown Planthopper (Nilaparvata lugens): a proteomic approach. Proteomics 9(10) : 2798-808.Yang H. et. al. 2002. Molecular mapping and genetic analysis of a rice brown planthopper (Nilaparvata lugens Stl) resistance gene. International Journal of Plant Breeding and Genetics 136(1) : 3943.