Abstract
Waxy maize rich in amylopectin has emerged as a preferred food. However, waxy maize is poor in lysine and tryptophan, deficiency of which cause severe health problems. So far, no waxy hybrid with high lysine and tryptophan has been developed and commercialized. Here, we combined recessive waxy1 (wx1) and opaque2 (o2) genes in the parental lines of four popular hybrids (HQPM1, HQPM4, HQPM5, and HQPM7) using genomics-assisted breeding. The gene-based markers, wx-2507F/RG and phi057 specific for wx1 and o2, respectively were successfully used to genotype BC1F1, BC2F1 and BC2F2 populations. Background selection with > 100 SSRs resulted in recovering > 94% of the recurrent parent genome. The reconstituted hybrids showed 1.4-fold increase in amylopectin (mean: 98.84%) compared to the original hybrids (mean: 72.45%). The reconstituted hybrids also showed 14.3% and 14.6% increase in lysine (mean: 0.384%) and tryptophan (mean: 0.102%), respectively over the original hybrids (lysine: 0.336%, tryptophan: 0.089%). Reconstituted hybrids also possessed similar grain yield (mean: 6248 kg/ha) with their original versions (mean: 6111 kg/ha). The waxy hybrids with high lysine and tryptophan assume great significance in alleviating malnutrition through sustainable and cost-effective means. This is the first report of development of lysine and tryptophan rich waxy hybrids using genomics-assisted selection.
Highlights
Waxy maize rich in amylopectin has emerged as a preferred food
Though large number of waxy maize cultivars are available for commercial cultivation worldwide[4], waxy maize protein is poor in nutritional quality due to sub-optimal levels of essential amino acids like lysine and tryptophan[6,13]
Identification of heterozygotes ( BC1F1 and BC2F1) and homozygotes ( BC2F2) at seedling stage helped in the exclusion of non-target progenies, resulting in significant savings of labour and material cost required for raising crops and pollination a ctivities[29,34]
Summary
Waxy maize rich in amylopectin has emerged as a preferred food. waxy maize is poor in lysine and tryptophan, deficiency of which cause severe health problems. The waxy hybrids with high lysine and tryptophan assume great significance in alleviating malnutrition through sustainable and cost-effective means This is the first report of development of lysine and tryptophan rich waxy hybrids using genomics-assisted selection. We report the development of lysine and tryptophan rich waxy hybrids by combining wx[1] and o2 genes through genomics-assisted b reeding[3,22]. The present investigation was undertaken to (1) introgress of wx[1] gene into elite o2-based (QPM) inbreds using marker-assisted backcross breeding (MABB), (2) evaluate the MABB-derived inbreds and reconstituted hybrids for amylopectin, lysine and tryptophan, and (3) assess the performance of MABB-derived inbreds and reconstituted hybrids for grain yield and agronomic traits
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