In Hordeum bulbosum technique the H. bulbosum chromosomes are eliminated during embryo development from a hybrid zygote (Barclay, 1975). In this system, the Crossability with wheat is constrained by the presence of incompatible genes (Kr1 and Kr2 ) situated on the 5A and 5B of wheat chromosomes that markedly reduce the crossability between wheat and H. bulbosum (Falk and Kasha 1981).for this reason, at present, the method using Hordeum bulbosum is restricted to crossable wheat genotypes. Nonetheless, maize pollen appears to be insensitive to these crossability limiting factors, and pollen can be taken from a wide range of maize germplasm (Suenaga 1994).
In maize mediated Dh system, the intergeneric crosses between wheat and maize followed …show more content…
cylindrica system of doubled haploidy (DH) breeding in wheat following chromosome elimination approach has following advantages over the existing wheat x maize system ( Chaudhary http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.558.7264&rep=rep1&type=pdf ):
• Coincidence of flowering : In wheat x maize system, maize has to be raised under artificial conditions in the green houses/polyhouses so as to coincide the flowering with that of wheat, whereas such exercise is not required in case of wheat x I. cylindrica system because I. cylindrica is a winter season plant and coincides well for flowering with that of wheat under natural conditions.
• Raising of pollen source: Maize has to be raised every season whereas I. cylindrica being a wild weedy perennial grass doesn’t require its repeated sowings. I. cylindrica is available under natural conditions in almost all parts of the world wherever wheat is cultivated.
• Genotype specificity: Both the plant species viz. maize and I. cylindrica are genotype non-specific for hybridization with any variety of wheat, triticale or their derivatives, proving their suoeriorty over anther culture system.
• Availability of pollen: Likewise maize, pollen of I. cylindrica is readily available in abundance during the wheat hybridization
In maize mediated Dh system, the intergeneric crosses between wheat and maize followed …show more content…
cylindrica system of doubled haploidy (DH) breeding in wheat following chromosome elimination approach has following advantages over the existing wheat x maize system ( Chaudhary http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.558.7264&rep=rep1&type=pdf ):
• Coincidence of flowering : In wheat x maize system, maize has to be raised under artificial conditions in the green houses/polyhouses so as to coincide the flowering with that of wheat, whereas such exercise is not required in case of wheat x I. cylindrica system because I. cylindrica is a winter season plant and coincides well for flowering with that of wheat under natural conditions.
• Raising of pollen source: Maize has to be raised every season whereas I. cylindrica being a wild weedy perennial grass doesn’t require its repeated sowings. I. cylindrica is available under natural conditions in almost all parts of the world wherever wheat is cultivated.
• Genotype specificity: Both the plant species viz. maize and I. cylindrica are genotype non-specific for hybridization with any variety of wheat, triticale or their derivatives, proving their suoeriorty over anther culture system.
• Availability of pollen: Likewise maize, pollen of I. cylindrica is readily available in abundance during the wheat hybridization