SSR marker aided introgression for opaque2 allele for development of quality protein maize inbreds

Abstract

Maize protein quality is deficit in essential amino acids, lysine and tryptophan. These constraints of o2 (opaque2) are corrected in genetically improved, hard endosperm QPM (Quality Protein Maize). An integrated strategy of phenotypic selection for endosperm modifiers and molecular marker-assisted foreground and background selection has been used in present study. The QPM donors were, CML 161, DMRQPM 58, CML 176 and CML 141 whereas, normal maize inbreds were CM 212, V338, V361, V336, V341, V351, CM 141 and V335. The inbreds were subjected to parental polymorphism survey between non-QPM and QPM using CIMMYT based three SSR markers, viz. phi057, umc1066 and phi112. Two markers, viz. phi057 and umc1066 exhibited co-dominant reactions, while phi112 was dominant in nature. Finally, two combinations V335 × CML 141 and V351 × CML 141 were considered for conversion program. Foreground selection was exercised using o2 specific marker umc1066 in BC 1 and BC 2 generations, while background as well as foreground selection was exercised in BC 2 F 3 generation to recover the genome of recurrent parent up to extent of 80 to 100% with the help of SSR markers distributed across the whole maize genome. The tryptophan concentration in endosperm protein was significantly enhanced and the converted maize lines had almost twice the amount of lysine and tryptophan than normal maize inbreds.

Quality protein maize (QPM): Genetic basis and breeding perspective

“…However, molecular marker based screening for QPM status coupled with phenotypic selection to improve endosperm characteristics seems to be an appropriate strategy for the development of QPM introgression lines. The erstwhile mentioned gene-specific co-dominant markers phi 057 (Manna et al 2005, Danson et al 2006, Magulama & Sales 2009) and umc 1066 (Singh & Ram 2014, Gupta et al 2009, Gupta et al 2013) are worthwhile to trace the opaque-2(o2) allele in conversion programme. Distinct polymorphism revealed by both the primers can discriminate the QPM donors from respective non-QPM recurrent parents and also between homozygous (o2o2) and heterozygous (o2o2) opaque-2 back cross progeny.…”

A Review on Breeding for Quality Protein Maize

“…Various markers are used to introgress o2gene intoelite maize inbred lines by rapid backcross conversion programme. They found that using a marker for QPM and endosperm modification can enormously improve the selection efficiency for isolating fully modified kernels in QPM background (55).…”