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Aphid-Borne Barley Yellow Dwarf Luteo Virus (BYDV). Viruses identified on Egyptian wheat and barley. Leafhopper-borne wheat dwarf mono- geminivirus (WDV) 2. Seed-borne barley stripe mosaic hordeivirus (BSMV) 3. Leafhopper-borne maize yellow stripe tenuivirus -like (MYSV)
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Viruses identified on Egyptian wheat and barley • Leafhopper-borne wheat dwarf mono- • geminivirus (WDV) • 2. Seed-borne barley stripe mosaic hordeivirus (BSMV) • 3. Leafhopper-borne maize yellow stripe tenuivirus-like (MYSV) • 4. Aphid-borne barley yellow dwarf luteovirus (BYDV).
History • 1982,Egyptian National Campaign • For wheat improvement has started • 1984,BYDV infection has been • recorded as sporadic single- infected plants in wheat fields of Lower Egypt (Abdel-Hak, 1984) • 1991,BYDV-RMV possible causal of severe outbreak in Mid Egypt maize fields (Aboul-Ata, et al, 1996)
1992,BYDV-PAV has been recorded and identified using Koch postulates (Aboul-Ata, et al, 1992) 1994,First record of 5 BYDV- serotypes (PAV, MAV, RPV, RMV and SGV) occurrence using DAS- ELISA at Purdue Univ., Indiana, USA (Lister, et al, 1994).
1994-2003, Egypt-ICARDA cooperation through Nile Valley Project funded by European countries. It deals with cereal viruses affecting wheat and barley 1994-1999, Different Wheat and barley germplasm were received from CIMMYT every year for BYDV-infection evaluation. Breeding program against BYDV has started 1994 1998,BYDV-PAV typing was done at INRA, France (Mastari, et al, 1998)
PROBLEM IDENTIFICATION
b a • External symptoms • caused by BYDV • Wheat, b. Patch of • infection on wheat • c. Patch of infection on barley c
1. • Morphology of major aphid vectors of BYDV • 2. Virus particles of different BYDVs 2.
1. Barley yellow dwarf luteovirus (BYDV) has different serotypes i.e. MAV, PAV and SGV • 2. Cereal yellow dwarf polerovirus • (CYDV) has different serotypes i.e. RPV and RMV • 3. There are almost 25 aphid species vector of both CYDV and BYDV
Sequences of the virus specific primers used in the multiplex RT-PCR detection method.
RT-PCR amplified products. M: 100 bp DNA ladder; L1: WSMV; L2: BYDV-PAV; L3: BYDV-MAV; L4: BSMV: L5: BYDV-MAV and BYDV-PAV.
4. BYDVs are transmitted persistently by aphid species and 24-48 hr is enough period as AAP 5. Monogenic incomplete dominant Yd2 and Bdv1 genes are BYDV resistance. 6. Resistance-breaking strains are mutually occurred
Cereal crop hosts of BYDV-PAV and RMV. Wild cereal plants as sources of BYDV-PAV infection are listed
BYDV-PAV Etiology, Typing and Sub-Typing
1. BYDV-PAV was isolated using R. padi. Virus detection was done using TBIA (Aboul-Ata, et al, 1992). 2. BYDV has five serotypes: PAV, MAV, RMV, RPV and SGV. All of them were recorded in Egyptian cereals (Lister, et al, 1996) 3. Symptom severity range (very severe – very mild/serotype/crop)
4. Dominant BYDV-PAV serotype has 2 subtype i.e. cpA and cpB. using Serological analysis by MAbs, RFLP and SSCP were used for differentiation .
BYDV-PAV sub-serotype (cpA and cpB) variants Healthy Control = Fresh weight (1.7) EW1 = Egypt isolate 1, EW2 = Egypt isolate 2
Phylogenic tree of BYDV-PAV for different cpA and cpB Sub-serotypes
BYDV Epidemiology And Non-insect Transmission
Monitoring of BYDV-vectored aphids in the season period using DAS-ELISA
Liner relation between BYDV-vectored aphids and BYDV infection
Non-insect inoculation Inoculation application for sauced seeds of wheat and maize kernels. One pin is used for virus inoculation into wheat seeds. More pines are used for virus inoculation into maize seeds
Insect inoculation for BYDV resistance • Mass rearing of • Healthy aphid (R. padi) • 2. Allow aphids to • acquire PAV-BYDV • 3. Inoculation of 3-leaf • stage wheat lines using • BYDV-vectored aphids. • Genotypic response against virus • 4. Spray insecticide to kill all insects used for Inoculation. • 5. Collecting field data and virus detection 45 days after inoculation.