Kerr, E. A.
Recent research has been chiefly with stablilized, commercial-type lines derived from L. hirsutum (Vagabond and Vinequeen) L. hirsutum var glabratum (V501). L. Peruvianlm (V542), L. pimpinellifolium PI 112215 (V545). Targinnie Red (SWST), L. pimpinellifolium PI 79532 = Mo. acc. 160, and L. cerasiforme. For simplicity, segregants have usually been divided into resistant (no sporulation) and susceptible (sporulation). There are differences however in the degree of resistance of the various segregants. In 1959 resistant types were usually sub-divided into immune and resistant, and susceptible into low resistant and susceptible. Sometimes resistant and low resistant types were further sub-divided and the segregants scored from 0 to 5. Each resistant may move to the next lower grade if environmental or time conditions are favorable. Accumulated backcross data on some varieties are as follows: SWST - 904R:1046S, V501 - 2674R:2474S, V545 - 125R:87S, Vagabond - 553R:455S. This indicates that in each variety we have one gene or two closely linked genes. The following F2 data on crosses between resistant varieties indicate multiple alleles, genetic and envirormental modifiers and crossovers.
Low
Parents Year Immune Resistant resistant Susceptible
V501 x V542 1959 155 150 0 0
V501 x V545 1959 59 111 1 1
V501 x Vagabond 1958 229 122 - 0
1959 117 134 0 0
V501 x Vinequeen 1959 65 91 5 (1 flat) 0
Vagabond x SWST 1958 202 122 - 26
Vagabond x V542 1957 79 11 - 0
1958 212 122 - 5
Vagabond x V545 1957 -- 90 - 0
1958 268 81 - 2
Low
Parents Year Immune Resistant resistant Susceptible
Vagabond x 1957 6 174 - 0
Vinequeen
1958 267 72 - 1
1959 163 131 0 0
Vinequeen x SWST 1959 98 149 24 0
Vinequeen x V542 1957 12 78 - 0
1959 133 68 0 0
Vinequeen x V545 1957 --- 90 - 0
The following backcross data are the only ones indicating linkage with other
plant characteristics. Most of these resistance genes are on chromosome 1.
Further tests are needed before they are given symbols and located on the
chromosome map.
Recombination
Variety Gens R+ R mut. S+ S mut. %
SWST br 138 124 96 132 44.9
y 165 117 123 195 40.0
V501 br 109 51 66 111 34.7
y 173 139 113 148 44.0
wt 338 238 214 258 43.1
V542 br 50 59 47 81 39.7
y 108 62 64 122 35.4
f 119 112 112 147 45.7
wt 96 91 73 96 46.1
V545 br 26 33 19 21 52.5
y 23 23 14 28 42.4
gf 18 9 6 12 33.3
Vagabond br 87 71 83 84 47.4
y 21 20 14 30 40.0
a 20 10 21 29 38.8