Title : Marker assisted breeding for beta carotene rich maize hybrids
Abstract:
The results presented here are a part of the breeding program conducted at the Maize Research Institute Zemun Polje with the aim to convert the standard maize (SM) to beta carotene rich (BCR) genotypes using the marker assisted backcross breeding. This breeding strategy gained immense importance as it precisely selects desirable plants and eliminates large scale biochemical estimation in the segregating generations. Two commercial SM hybrids and their BCR counterparts were the subjects of this research. Parental lines of BCR hybrids were developed through marker-assisted introgression of crtRB1-3?TE allele. The conversion process included three generations of backcrossing and two generations of selfing. Biochemical evaluation of resulting improved hybrids was performed to estimate beta carotene, tryptophan and protein contents. In both BCR hybrids, BC content was significantly higher (p<0.01) in comparison with the standard hybrids, confirming the success of the conversion process. Unlike the SM where tryptophan is a deficient amino acid, in BCR hybrids it was increased for 15.04% and 19.93%, respectively. Quality index (QI), defined as tryptophan to protein ratio, was also elevated for 13.75% in BCR1 and for 9.39% in BCR2. Being the major indicator of protein quality, increased QI implies improved nutritional quality of the protein in BCR hybrids. Furthermore, highly significant correlation (p<0.01) was identified between QI and BC, indicating the possibility of simultaneous selection and improvement of these traits in our breeding material. These two beta carotene enriched hybrids with improved protein quality can be used in the biofortification programs.
