IDENTIFICATION OF RESISTANT SOURCES FOR BPH, Nilaparvata lugens (Stål) AND MOLECULAR CHARACTERIZATION OF DIFFERENT BPH POPULATIONS
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Date
2019
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Acharya N G Ranga Agricultural University, Guntur
Abstract
The present investigation was undertaken with an aim to identify the resistant sources of brown planthopper, Nilaparvata lugens (Stål) among 1110 ENRRD (Establishment of Rice Resource Database) germplasm lines. Resistance mechanism Studies were carried out on the selected resistant lines. In another study efforts were made to identify the biochemical basis of resistance in the identified sources. Attempts were also made to validate the BPH resistant genes in the identified resistant lines. Standard Seed box screening was conducted during 2016-17 for 1110 germplasm lines in two replications. Among 1110 rice germplasm tested, 3 were categorized as highly resistant, 24 as resistant, 19 as moderately resistant, 192 as moderately susceptible, 509 as susceptible and rest of other 363 genotypes were highly susceptible to BPH. Honeydew excreted by the third instar nymphs and one day old adults was significantly lowest in the germplasm accessions IC 343394, IC 577624 and IC 377527 indicating antixenosis mechanism. The studies on probing marks revealed that resistant entries, IC 464944 and IC 377527 was least preferred by BPH nymphs for settling, received more number of probing marks The results indicate that the IC 377527, IC 343457 and IC 300168 possess non-preference / antixenosis mechanism of resistance and are not preferred by BPH either for shelter or feeding. The studies on nymphal growth and development, % macroptery and sex ratio, indicate that survival of BPH nymphs was significantly low on resistant entries compared to moderately resistant and susceptible entries. On resistant entries viz., IC 577624, IC 450041 and IC 343394 nymphal survival was very low i.e. 31.11, 35.56 and 37.78 per cent respectively, whereas resistant and susceptible checks viz., Ptb 33 and TN1 recorded 39.6 and 93.3 per cent nymphal survival respectively. Brachypterous females were higher than macropterous females in all the entries including susceptible check, TN1. However, on resistant entry, IC 377051 and IC 343392, macropterous females were higher than brachypterous females. Macropterous males were more than brachypterous males in all the entries except IC IC 300167 and IC 300202. Growth index of BPH was low on the resistant entries
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compared to susceptible entries 2.48 - 9.49 indicating unsuitability of the cultivar for growth and development of BPH The studies on nymphal growth and development, % macroptery and sex ratio in the BPH on resistant and susceptible ENRRD entries indicate the presence of antibiosis mechanism of resistance in the resistant entries IC 343394, IC 450041 and IC 343392 where nymphal survival was reduced, nymphal duration was prolonged and growth index was low. The biology of BPH was adversely affected on the resistant entries, but not in case of susceptible entries. Tolerance studies revealed that resistant entries, IC 343457, IC 343394 and IC 319799 required more days to wilt, 36.67, 34.33 and 33.67 days, respectively and was on par with the resistant check, Ptb 33 (35.67 days) and susceptible check TN1 wilted in 12.33 days. The correlation studies of damage score with the parameters revealed that damage score and honeydew area of both nymphs and adults are positively correlated and highly significant. Days to wilt exhibited as highly significant negative correlation with BPH reaction. BPH infestation on most of the resistant cultures and resistant check Ptb 33 resulted in an increase in the phenolic content in the infested plant. Significantly highest phenolic content (45.37 mg g-1 tissue) was observed in infested IC 300202 compared to all test cultures including resistant check Ptb 33. The total sugar content was significantly highest in the uninfested susceptible check TN1 compared to the resistant and moderately resistant cultures. Upon infestation of BPH there was a decrease in total reducing sugars in all the plants. However, when infested IC 343457 (7.55) showed slight decrease in sugars which was on par with Ptb 33 (9.57). The high quantity of amino acid was present in IC 343457 (4.36) and IC 449821 (4.47), IC 545441 (3.99) & IC 343394 (3.17) which was on par with resistant check PTB 33 (2.85) and which is significantly different from susceptible check TN1 (1.97). In the infested paddy cultures, there was an increase in the amino acid content in all the resistant cultures including the checks (20.72% to 76.86%). Highest per cent of increase observed in IC 300168 (76.86) which is more than PTB 33, least per cent of increase in amino acids was recorded in IC 545441 (20.72) i.e., more than TN1 (17.92). In general the total N content in the infested cultures decreased over healthy plants in most of the rice cultures and it varied with the culture. Decrease in the N content was highest in the susceptible variety TN1 (38.3%). In the resistant Ptb 33 decrease in the N content was marginal (10.13%).The P and K contents of the selected rice germplasm accessions were also estimated. Potash content was more or less same in all the selected rice germplasm accessions tested before infestation. However, some increase after infestation was observed in the resistant cultures and resistant check Ptb 33, but not in susceptible TN1. Molecular profiling by using 17 SSR markers for detecting 9 Bph genes revealed the presence of Bph6 gene in IC 300167 and Bph18 gene in IC 301181, IC 319799, IC 450041 IC 343392, IC 343457 and IC 449821. The markers RM28004 of Bph1 gene, RM589 of Bph3 gene, RM313 of Bph7 gene, RM8213 & RM5953 of Bph17 gene, RM435 & RM540 of Bph20 gene and RM8072 of Bph32 gene were failed to show polymorphism between resistant and susceptible checks. However, new alleles were reported in some entries, these new alleles might be source for BPH resistance in these lines. The number of alleles per marker ranged from 1 to 10 with an average of 3.94 alleles indicating the presence of average allelic diversity. The PIC values of 17 SSR markers used in our study varied from 0 (RM5953) to 0.84 (RM586) with an average of 0.46. While, The overall He values ranged from 0 (RM5953) to 0.86 (RM586) with an average of 0.53. The 24 genotypes categorized into four major
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clusters at 30% level of genetic similarity. Most of the resistant genotypes were grouped under major cluster III. Cluster I consist of only Mudgo, cluster II comprised of resistant donor, TN1 and BPT 5204. Cluster III includes Sampada, IC 300168, IC 343394 and IC 450041. Major Cluster IV included 4 rice genotypes, IC 377051, IC 49821, IC 343457 and IC 577624. Study was conducted to study the variability of BPH populations by collecting BPH insects from different places of India like West Godavari (Maruteru, AP), Nellore (AP), Nalgonda (Kampasagar, TS), Toofran (Medak Dist., TS), Bargarh (Orissa), Gangavathi (Karnataka), Raipur (Chattisgarh) and IIRR Glasshouse. Phenotypic studies were performed on thirty different gene differentials with Reference TN1 as susceptible check. Among all the populations Gangavathi population was observed as highly virulent and least virulent was Bargarh. Average damage scores on gene differentials by all BPH populations were as follows: Gangavathi (DS 7.98), Glasshouse (DS 7.28), West Godavari (DS 7.24), Nellore (DS 7.13), Raipur (DS 6.8), Nalgonda (DS 6.76), Toofran (DS 6.51) and Bargarh (DS 5.06). Based on average scores of gene differentials when screened with all the eight populations RP 2068 (DS 2.56) and ARC 10550 (DS 4.85) were proved to be resistant The clustering analysis of eight Brown planthopper populations collected from different regions of India was done using damage score revealed the presence of three groups. Group 1 consists of three populations viz., Bargarh population (Orissa), Toofran (Medak Dist., TS) and Raipur (Chattisgarh). But Raipur (Chattisgarh) population outgrouped from other two populations. Group- 2 is comprised of two sub groups viz., Gangavathi (Karnataka) & West Godavari (Maruteru, AP) as one and IIRR glasshouse population as another sub group. Group 3 includes Nalgonda (Kampasagar, TS) and Nellore (AP) populations. In order to study the genetic variability eight Brown planthopper populations collected from different regions of India. Six SSR markers from each linkage chromosome of bph were selected and run to check the polymorphism. When cluster analysis using genotypic data was done, eight populations were grouped into three clusters. Group 1 consists of four populations i.e., IIRR glasshouse population, Bargarh population (Orissa), Raipur (Chattisgarh) and Gangavathi (Karnataka). Group 2 consists of three populations viz., Nalgonda (Kampasagar, TS), Nellore (AP) and west Godavari (Maruteru, AP), Toofran (Medak Dist, TS) BPH population alone grouped into one (Group 3) with the similarity of 0.35. When both genotypic and phenotypic grouping is compared Nalgonda & Nellore populations, Raipur & Bargarh populations, Gangavathi & Glasshouse populations were found to be similar whereas West Godavari and Toofran are differing in grouping phenotypically and genotypically.
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D5852
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