The Eleventh Regional Wheat Workshop For Eastern ... - Cimmyt

Sources ofvariability ofgenes for yellow rust resistance - Singh and Huerta-Espino
Answer: In the broad sense, yes! Exceptions can always be found in nature.
Colin Wellings: Given that estimations of additive gene number involve relatively small
frequencies of homozygous parental types, do you see any advantage in DB versus RIL
populations?
Answer: No, because at CIMMYT we can obtain RlLs (Recombinant Inbred Lines, F5 or F6)
in the same time as one can obtain enough seeds ofDH. Ratios are changed only slightly
from F6 to DB.
Colin WeHings (Comment following Ravi Singh's comment): The evidence suggests that
virulence to Yr9 arose in the late 1980s in Ethiopia, and subsequently transferred to the high
elevation mountain plateau of Yemen. From there the new rust pathotype survived, and
spread to the Nile Valley, Middle East and beyond. These observations would support Dr.
Singh's concern.
F3 lines (No.)
60
50
40
30
..
20 o
C.
10
.