Marker assisted breeding for introgression of opaque-2 allele into elite maize inbred line BML-6

Abstract

Improvement of QPM (Quality Protein Maize) along with high content of lysine and tryptophan had foremost importance in maize breeding programme. The efficient and easiest way of developing QPM hybrids was of backcross breeding in marker aided selection. Hence the present investigation was aimed with an endeavour to convert elite maize inbred line BML-6 into QPM line. CML-181 was identified to be a donor variety as it revealed high-quality polymorphism with BML-6 for opaque-2 gene specific marker umc1066. Non-QPM inbred line BML-6 was crossed with QPM donor CML-181 and produced F1 followed by BC1F1 and BC2F1 population was developed. Foreground selection was carried out with umc1066 in F1, and selected plants were used for BC1F1 and BC2F1 populations. Two hundred plants were screened in both BC1F1 and BC2F1 population with umc1066 for foreground selection. The selected plants were screened for foreground selection with amino acid modifiers. Foreground selected plants for both opaque-2 and amino acid modifiers were screened for background selection for BML-6 genome. Recurrent parent genome (RPG) was determined for BC2F1 population plants. Three plants have shown with RPG 90–93% in two generation back cross population. Three selected BC2F2 populations were screened for foreground and back ground selection followed by agronomical and biochemical evaluation. The QPM converted version of BML-6 contains 0.97% of tryptophan and 4.02% of lysine concentration in a protein. Agronomical and biochemical screened BC2F2 plants were selfed for BC2F3. QPM version of BML-6 line can be used for the development QPM version of maize single cross hybrids.