Biotic Stress and Crop Improvement: A Wheat Focus Around Novel Strategies - Crop Improvement: New Approaches and Modern Techniques - page 238

Chapter 7
Biotic Stress and Crop Improvement: A Wheat
Focus Around Novel Strategies
Alvina Gul Kazi, Awais Rasheed and Abdul Mujeeb-Kazi
Abstract Currently much of the wheat genetic variability is obtained through con-
ventional crop improvement methods involving land races and normal varieties.
Hence, the germplasm base available in the form of cultivars is becoming increas-
ingly narrow and the need for widening the gene pool is essential in view of the
emerging biotic and abiotic stresses due to global warming and climate change.
Major abiotic constraints that have surfaced are due to increased salinity, water log-
ging, drought and heat. Biotic stresses of emphasis here additionally contribute to
the crops productivity situation. To counter these maladies a broad genetic base
is essential to have on hand and its implementation a dire need forming the focus
of this communication. New and useful genetic variations exist in the wild uncul-
tivated wheat progenitor species that can be utilized for the enhancement of the
existing wheat breeding pools and improve yield stability. These genetic variations
can be harnessed through a combination of conventional breeding methods coupled
with interspecific, intraspecific and intergeneric hybridization approaches popularly
known as “wide crossing” that independently and cumulatively augment the avail-
able genetic variability for wheat improvement.
Diploid wheat progenitors (2n = 2x = 14) A, B, and D are the constituents of
bread wheat ( Triticum aestivum L) offering extensive diversity that contributes to
crop improvement by providing novel allelic enrichment. A and D genome dip-