Biotic Stress and Crop Improvement: A Wheat Focus Around Novel Strategies - Crop Improvement: New Approaches and Modern Techniques - page 250

genitors, the D genome diversity at the basic primary level and for the advanced
derivatives became significant for wheat breeding efforts. From the Mayoor and
Sabuf test scores of 9-2-9-4 (9-9 susceptible) screening and a grain finish between
1 and 3 (5 poor blemished grain) the derivatives and D genome stocks utilizing
Ae . tauschii produced selected products that scored 9-2 with a grain finish of 1-2.
These were far superior than Mayoor and Sabuf and utilized via gene pyramid-
ing options. Mayoor was hybridized with a synthetic combination TKSN1081/Ae.
tauschii (222) to yield superior spot blotch resistant derivatives which also possess
multiple disease resistance that covers scab (type 1-4), Septoria and karnal bunt.
Both Mayoor and Sabuf have been further utilized in the development of molecular
mapping populations with susceptible wheat Flycatcher and Ciano (Mujeeb-Kazi
et al. 2004 ) as follows:
1. Mayoor//TKSN 1081/ Ae tauschii (222)/3/Flycatcher with 171 doubled haploids
2. Sabuf/3/Bacanora//Ceta/ Ae. tauschii (895)/4/Flycatcher with 125 doubled haploids
3. Sabuf/3/Bacanora//Ceta/ Ae. tauschii (895)/4/Ciano with 102 doubled haploids.
The above populations are a conduit for molecular studies involving QTL mapping
aspects and testing internationally.
KarnalBunt
This soil borne disease ( Neovossia indica ) is a tremendous quarantine concern as
once the soil is infected its occurrence is un-ending. The national level of accep-
tance of grain for consumption is set for 3 % infection. Grains shipped across na-
tions spread the disease if they carry it and thus caution is exercised to wash seed,
treat it and stringently apply quarantine testing to provide seed disbursement that is
virtually 0 % infectious. Disease free sites are used for seed increase as in Mexico
by CIMMYT. However some countries are lax as to the seed been tested across
wheat cultivation zones and danger prevails as to its spread. Diversity for resis-
tance exists and breeding efforts are preferred. Durum cultivars are generally field
resistant with bread wheats open to high susceptibility levels. Search for resistant
resources has been a priority for the past 2-3 decades. Since swift outputs have been
sought the choice of the D genome has had a high priority and fortuitously the SH
wheats derived from durum/ Ae. tauschii combinations gave outputs where immu-
nity was abundant in the materials tested. Stringent testing under controlled testing
made the field resistant durums susceptible with their SH products remaining im-
mune (Villareal et al. 1996 ); an unequivocal proof that D genome accessions carried
the resistance. This led to the identification of user friendly developed stocks and
their registration (Mujeeb-Kazi et al. 2001b ). Further the SH wheats upon crossing
to susceptible elite bread wheats gave derivatives that had resistance transferred
into the selections (Mujeeb-Kazi et al. 2006a ). The identification of QTLs under-
lying the resistance to karnal bunt has been carried out using disease screening in
multiple-environment data and it was established that two major QTLs reside on