Rice tungro disease management - IRRI books - International Rice ...

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Developing breeding lines with RTD resistanceIn 1994, a special breeding project began with tungro resistance as the primary trait ofinterest. The project aims to develop lines with resistance to tungro using variousdonor sources. By backcrossing and/or selection in the segregating population, resistancegenes are transferred to a modem genetic background. The project seeks toproduce breeding materials with durable resistance to either RTSV or rice tungrobacilliform virus (RTBV) or to both viruses, with or without resistance to the vector.With the availability of these breeding lines, the efforts of breeders working mainlyon high yield and good grain quality will become easier and faster. This prevents theoccurrence of undesirable recombinants that arise when landraces are used as sourcesof resistance. It also disrupts the progress in generation advance by reintroducingmany undesirable traits into lines that have been previously considered promising forother traits. Thus, instead of, for instance, using Utri Merah directly, the resistancegene can be transferred into promising selections by way of breeding lines containingthe resistance gene but with improved characteristics.For most of the activities under this project, workers at the PhilRice CentralExperimental Station (CES) in Muñoz, Nueva Ecija, work closely with researchers atthe PhilRice Midsayap Experiment Station (MES) in North Cotabato. CES acts mainlyas a source of materials while conducting field tests on its own and performs the moresophisticated laboratory procedures. MES serves as a satellite station for field testsand as a second source of leaf samples to be analyzed by enzyme-linked immunosorbentassay (ELISA), which is the responsibility of CES. Midsayap is strategically locatedbecause of the constantly high insect and disease pressure in the area notably includingtungro. With the strengthening of networks, the research group at MES has startedperforming its own crossing work and is now also equipped with a green leafhopperrearingnursery for virus strain maintenance and test tube inoculation.Breeding and screening strategiesModern varieties, landraces, introductions, and breeding lines are first evaluated fortheir response to tungro disease using visual screening and ELISA. Selected moderngenotypes are then crossed with resistance donors. Table 1 lists materials used in thecrossing work conducted from 1994 to 1996.F 1 and F 2 plants are reared in CES. Individual plant selection begins with F 2plants, which are space-planted in the field. During the wet season (WS), when diseasepressure is high, selection is primarily for resistance (visual screening). Duringthe dry season (DS), when disease pressure is insignificant, selection is primarily formorphology and grain structure.Starting at F 3 , dual-location testing is carried out at both CES and MES. Duringwet seasons, generation advance and field screening are conducted at both CES andMES. Only generation advance activities are conducted at CES during dry seasons,however, because of very low occurrence or nonoccurrence of tungro in Central Luzonat this time of the year.24 Sebastian et al
Table 1. Parental materials used in hybridization work for rice tungro disease resistance,1994-96.Resistance donorsUtri MerahModern varieties/lineslR65564-22-2-3lR65597-134-2-3-1lR65597-17-4-3-3lR65598-112-2lR65600-12-3lR65600-27-1-2-2lR65600-32-4-6-1lR65605-6-2-3-2lR66158-38-3-2-1lR66159-164-5-3-5lR66160-5-2-3-2lR66165-24-6-3-2lR66738-118-1-2lR66750-6-2-1IR66764-AC4-8lR66160-121-4-1-1ARC11554T1-11-8T15725T15850T15943T15950T15991T16000T16270T16291T16393LS519LS551TK298TK300TK303TK342TK352DS1-1DS1-7KataribhogUtri RajapanLS546IR22M seriesBPI Ri10C4-63GIR24IR56IR64IR72PSB Rc4PSB Rc14PSB Rc40lR54883IRBB5IRBB21PSB Rc40HabatakiTakanarlTodorikiwasiCR2CR3CR5CR93CR94LH422LX37LX76LX77LX93LX99LX136LX144aLX144bLX163PR26494The F 3 materials are planted in small (2.2-2.8 × 1.2-1.6 m), unreplicated plots.Selection is done within plots and seeds are bulked in each plot to constitute the nextgeneration. At F 4 and F 5 , the small plots are replicated thrice. Selection is still withinplots and seeds are also bulked, Lines that are consistently damaged by tungro in allthree replicates are dropped, whereas lines that show a high degree of resistance in allthree replicates are considered as the best selections. At F 6 through F 8 , lines are plantedin unreplicated but bigger plots (5.0 × 5.0 m) to minimize escape and/or preference ofinsects, which is especially the case when many genotypes are arrayed in successionin the field. At this stage, selections within each plot can be separated into distinctsublines, but each subline can still be composed of several bulked plants. Visual screeningis also coupled with ELISA at this stage. Promising selections are then tested inpreliminary yield trials.The ELISA technique is carried out as outlined by Bajet et al (1985). Leaves aresampled at 30 and 60 d after transplanting (DAT). Absorbance is set at 405 nm in aMicroELISA reader. For the field screening. spreader rows consisting of IR64 or PSBRc14 are planted 1 mo ahead to ensure a sufficient source of virus. Disease incidence(% infection) is observed at 30 and 60 DAT.Rice tungro disease observation nurseryThis part of the project aims to (1) evaluate selected rice collections and advancedlines for resistance to rice tungro disease and (2) identify potential parents for hybridizationwork. An initial screening of 56 commercial varieties and breeding lines wasconducted at CES and MES in the 1995 WS. The entries were assigned to 1.0 × 2.5-m plots each in three replications. Visual scoring of tungro incidence and leaf samplingfor ELISA were done at 30 and 60 DAT.Breeding for rice tungro disease 25
Page 2 and 3: RiceTungro DiseaseManagementEdited
Page 4 and 5: ContentsRice tungro disease in the
Page 6 and 7: ForewordThe intensification of rice
Page 8 and 9: PrefaceProviding farmers with optio
Page 10 and 11: Rice tungro disease in the Philippi
Page 12 and 13: Cotabato, and Laguna) during 1995-9
Page 14 and 15: seed growers and farmers to increas
Page 16 and 17: Fig. 2. Incidence of rice tungro di
Page 18 and 19: De los Reyes JB, Cabunagan, RC, Col
Page 20 and 21: Preliminary analysis of genetic var
Page 22 and 23: Fig. 2. Distinct rice tungro bacill
Page 24 and 25: Fig. 4. Dendogram depicting the rel
Page 26 and 27: Preliminary analysis of genetic var
Page 28 and 29: Table 1. Size characteristics of th
Page 30 and 31: varieties and did not seem to exert
Page 34 and 35: In CES, 28 entries had low tungro i
Page 36 and 37: Table 2. Best rice tungro disease-r
Page 38 and 39: Breeding for rice tungro virus resi
Page 40 and 41: Table 2. Promising lines resistant
Page 42 and 43: Table 4. Rice cultivars used as hyb
Page 44 and 45: Shahjahan MB, Jalani S, Zakri AH, I
Page 46 and 47: Table 1. Initial 19 transgenic line
Page 48 and 49: Table 4. Percent infection of trans
Page 50 and 51: very low level. In fact, transgene
Page 52 and 53: of Agricultural Research (ICAR). Pr
Page 54 and 55: Fig. 2. Mean infection with rice tu
Page 56 and 57: (RTBV) and rice tungro spherical vi
Page 58 and 59: Table 4. Percent infection a with r
Page 60 and 61: GLH numbers were much lower on IR62
Page 62 and 63: Cabunagan RC, Hibino H, Sama S, Riz
Page 64 and 65: Prospects of virus-resistant variet
Page 66 and 67: Tungro in Bali (1987-97)Tungro infe
Page 68 and 69: Fig. 5. Proportion of varieties gro
Page 70 and 71: Table 3. Percent incidence of rice
Page 72 and 73: Evaluating rice germplasm for resis
Page 76 and 77: Rice tungro disease resistance andm
Page 80 and 81: ecommended vector-resistant variety
Page 82 and 83:
Materials and methodsBatches of ant
Page 84 and 85:
ReferencesClark MF, Adams AN. 1977.
Page 86 and 87:
(e.g., Sokal and Rohlf 1995, p 213;
Page 88 and 89:
Surveillance scheme for tungro fore
Page 90 and 91:
entrusted with implementing the pro
Page 92 and 93:
Table 1. Number of mobile nursery t
Page 94 and 95:
are implemented immediately. The co
Page 96 and 97:
Farmers’ rice tungro managementpr
Page 98 and 99:
Experience with tungroAlthough both
Page 100 and 101:
Table 5. Farmers (%) reporting tung
Page 102 and 103:
Table 7. Farmers’ reported tungro
Page 104 and 105:
Table 9. Mean number (standard devi
Page 106 and 107:
than rice), so they may be reluctan
Page 108 and 109:
Community-based rice pest managemen
Page 110 and 111:
Establishment of farmers’ indigen
Page 112 and 113:
Meanwhile, insects, diseases, and n
Page 114 and 115:
Table 2. Most important diseases fo
Page 116 and 117:
Farmers’ knowledge of pest contro
Page 118 and 119:
ha -1 and above) had a lower RTD in
Page 120 and 121:
Fig. 4. Three major peaks of green
Page 122 and 123:
RBB hill -1 and 4% WSB (Fig. 6). In
Page 124 and 125:
The influence of varietal resistanc
Page 126 and 127:
Limited data exist on how resistant
Page 128 and 129:
tember plantings, reaching 13% and
Page 130 and 131:
Holt J, Chancellor TCB, Reynolds DR
Page 132 and 133:
glh4, respectively. Planting at the
Page 134 and 135:
Results and discussionMinimum unit
Page 136 and 137:
Fig. 4. Transmission efficiency of
Page 138 and 139:
Table 1. Enzyme-linked immunosorben
Page 140 and 141:
Leafhopper control by insecticides
Page 142 and 143:
Fig. 1. Cartoon used for tungro man
Page 144 and 145:
The role of vector control in rice
Page 146 and 147:
To establish relationships between
Page 148 and 149:
Fig. 1. Influence of antifeedants o
Page 150 and 151:
Fig. 4. Tungro incidence before har
Page 152 and 153:
ReferencesAryawan IGN, Widiarta IN,
Page 154 and 155:
Materials and methodsSeedbed protec
Page 156 and 157:
Table 2. Relationship of RTD incide
Page 158 and 159:
Management of rice tungro disease b
Page 160 and 161:
Results and discussionGLH populatio
Page 162 and 163:
Table 4. Field evaluation of foliar
Page 164 and 165:
3.6 to 2.7 t ha -1 . These yields w
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