30                         PNL Volume 20                     1988 RESEARCH REPORTS
SOURCES OF RESISTANCE TO PATHOTYPES OF PEA SEED-BORNE MOSAIC VIRUS IN THE U.S. PLANT INTRODUCTIONS OF PISUM SATIVUM
Provvidenti, R., and R. Alconero                       New York State Agricultural Exp. Station
Cornell University, Geneva, NY 14456; and USDA Germplasm Resources, Northeast Regional Plant Introduction Station, Geneva, NY
In his 'Geographic origin of pea seedborne mosaic virus: An hypothesis', R. O. Hampton listed 39 accessions of Pisum sativum reportedly resistant to pea seed-borne mosaic virus (PSbMV) (4). Twenty eight of these lines (72%) were from India, of which 25 derived from Uttar Pradesh. These and a few other lines were tested with five isolates of PSbMV {(Standard (ST), Pea 1 (P1), Lentil L (L), Lentil 1 (L1), and Pea 4 (P4)} (1,3) and the results (Table 1) can be summarized as follows:
- All lines reacted identically to ST and P1 isolates, which incited similar foliar symptoms in susceptible genotypes. Hence, these two isolates should be considered members of the same pathotype, PSbMV-ST. Resistance is conferred by the gene sbm-l. which is located on chromosome 6 (2,3).
- Also, all lines responded identically to L and L1 isolates. However, in susceptible genotypes, L caused mild mottle and slight downward leaf cupping, whereas L1 incited prominent chlorotic mottle, upward leaf curling, flower abortion, and severe stunting. Consequently, these isolates should be regarded as two different strains of the same pathotype, PSbMV-L. The genes sbm-2 and sbm-3, independently of each other, confer resistance to both strains of this pathotype, and may be duplicate entities (5). The gene sbm-2 is located on chromosome 2 (5).
- Resistance to P4 was found associated with that to PSbMV-ST and PSbMV-L or with one of these two pathotypes, but never alone. In susceptible plants, PSbMV-P4 caused moderate to prominent mottle with a partial recovery on subsequent growth. Resistance is conferred by sbm-4 (6).
Thus, of 45 accessions: a) 29 were resistant to PSbMV-ST, PSbMV-L, and PSbMV-P4; b) two were resistant to ST and L, but susceptible to P4; c) three were resistant to L and P4, but susceptible to ST; d) one was resistant to ST, but susceptible to L and P4; e) five were resistant to L, but susceptible to ST and P4; and f) five were susceptible to ST, L, and P4.
These tests are in agreement with the results of previous work, which concluded that: a) there are at least three pathotypes of the virus, PSbMV-ST, PSbMV-L, and PSbMV-P4 (1,3,5,6); b) resistance is pathotype specific (1); and c) resistance is governed by distinct genetic factors that are independently inherited (2,5,6). However, the frequent association of resistance to the three pathotypes in most of the lines from India and Ethiopia suggest that the genes sbm-1. sbm-3 and sbm-4 may be linked.
1.    Alconero, R., R. Provvidenti, and D. Gonsalves. 1986. Plant Dis. 70:783-786.
2.    Gritton, E. T., and D. J. Hagedorn. 1975. Crop. Sci. 15:447-448.
3.    Hagedorn, D. J., and E. T. Gritton. 1973. Phytopathology 63:1130-1133.
4.    Hampton, R. 0.1986. PNL 1822-26.
5.    Provvidenti, R., and R. Alconero. 1988. J. Heredity 79: Jan.- Feb. Issue
6.    Provvidenti, R., and R. Alconero. 1988. J. Heredity 79: Jan.- Feb. Issue
PNL .Volume 20                     1988 RESEARCH REPORTS                     31
Table 1. Sources of resistance to pathotypes of PSbMV in Plant Introduction of Pisum sativum
PSbMV-ST
PSbMV-L
PSbMV-P4
Accession No.
Origin
ST P-1
L L-1
P-4
PI 175877
Turkey
S
R*
S
PI 193584
Ethiopia
R*
R*
R
PI 193586
Ethiopia
R
R
R
PI 193587
Ethiopia
R*
R*
R*
PI 193835
Ethiopia
R*
R
R
PI 193836
Ethiopia
R*
S
S
PI 244054
Yemen
S
S
S
PI 269774
England
R
R
S
PI 269818
USSR
R
R
S
PI 314795
Australia
S
S
S
PI 343305
Idaho
S
S
S
PI 343328
Idaho
S
S
S
PI 343333
Idaho
S
S
S
PI 347328
India U.P
R
R
R
PI 347329
India U.P
S
R
R
PI 347420
India U.P
S
R
S
PI 347421
India U.P
R
R
R
PI 347422
India U.P
S
R
R
PI 347442
India
R
R
R
PI 347452
India U.P
R
R
R
PI 347455
India U.P
R*
R
R
PI 347456
India U.P
R*
R
R
PI 347464
India U.P
S
R
R
PI 347465
India U.P
R
R
R
PI 347466
India U.P
R
R
R
PI 347467
India U.P
R*
R
R
PI 347468
India
R*
R
R
PI 347469
India U.P
R*
R
R
PI 347470
India U.P
R
R
R*
PI 347482
India U.P
S
R*
S
PI 347484
India U.P
S
R
S
PI 347485
India U.P
R
R
R
PI 347487
India U.P
R
R
R
PI 347492
India U.P
R*
R
R
PI 347494
India U.P
R
R
R
PI 347523
India.U.P
R*
R
R
PI 347528
India U.P
S
R
S
PI 356984
India U.P
R
R
R
PI 357003
India U.P
R
R
R
PI 357005
India U.P
R
R
R
PI 357015
India U.P
R
R
R
PI 357023
India U.P
R
R
R
PI 357026
India
R
R
R
PI 357038
India UP
R
R
R
PI 378158
Malaysia
R
R
R
R = Resistant; S = Susceptible; * = Reported or found to contain some susceptible plants
NOTE: Due to the heterogeneity of many P.I. seed lots, lines reported to be fully resistant may also
iclude some susceptible plants.
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