Use of maize X Tripsacum hybrids for stress breeding in maize
1994
Jewell, D.C. | Islam-Faridi, N. (Centro Internacional de Mejoramiento de Maiz y Trigo (CIMMYT), Mexico, DF (Mexico). Maize Program)
CIMMYT has been involved in research on wide hybridization on maize since mid-1970s. This research has been viewed as long-term and complementary to both CIMMYT breeding objectives and to activities in genetic conservation of the wild relatives of maize. Hybrids between maize and Tripsacum have been obtained by many researchers during the last 50 years. Ten years ago CIMMYT initiated a backcross program to isolate individual chromosomes of Tripsacum in a tropical maize background (Tripsacum addition lines). Backcross 10 generation plants have now been produced. A major barrier to the utilization to this genetic resource for maize improvement has been the absence of suitable methods for obtaining maize that is introgressed with small segments of Tripsacum chromosomes. Hybrids between maize and Tripsacum can take more than 300 days to flower and progress towards obtaining maize with one additional chromosome from Tripsacum is further delayed if the hybrid and its backcross derive progeny exhibit high levels of apomixis. In 1990-91 the CIMMYT wide cross unit had isolated the first tentatively identified Tripsacum addition lines. During the first 12 months, considerable time and effort were placed on improving our ability to identify maize chromosomes cytologically at mitosis. About 50 inbreed maize lines were studied and this work has led to an increased appreciation of the variability if maize chromosomes for both relative length and arm ratio
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