Maize Genetics Unit, ICAR-Indian Agricultural Research Institute, New Delhi, 110012, India.
Maize Genetics Unit, ICAR-Indian Agricultural Research Institute, New Delhi, 110012, India.
Plant Sci. 2018 Jul;272:142-152. doi: 10.1016/j.plantsci.2018.04.014. Epub 2018 Apr 18.
The improvement of protein quality in maize so far has been based on recessive opaque2 (o2) mutant that along with endosperm-modifiers led to development of quality protein maize (QPM). Recent discovery of nutritional benefits of recessive opaque16 (o16) mutant was of immense significance for further improvement of protein quality. In the present study, o16 was introgressed into o2-based parental inbreds (HKI161, HKI193-1, HKI193-2 and HKI163) of four commercial QPM hybrids (HQPM-1, HQPM-4, HQPM-5 and HQPM-7) released in India, using marker-assisted backcross breeding. Background selection led to high recovery of recurrent parent genome (RPG) to maximum of 95%, and introgressed progenies showed considerable phenotypic resemblance for plant-, ear- and grain- characteristics to their respective recurrent parents. Selection of markers for o2 and o16 led to development of pyramided lines (o2o2/o16o16) that possessed as high as 76% and 91% more lysine and tryptophan over the recurrent parents, respectively. Reconstituted hybrids showed an average enhancement of 49% and 60% in lysine and tryptophan over the original hybrids, with highest enhancement amounting 64% and 86%, respectively. This is first report of enhancement of both lysine and tryptophan by o16 in maize genotypes adaptable to sub-tropics. Moderate variation in lysine and tryptophan was also observed in pyramided lines. Multi-location evaluation of reconstituted hybrids revealed similar grain yield and attributing traits to their original versions. This study signified the role of o16 as supplementary to o2 for nutritional quality enhancement in maize, and improved elite inbreds and hybrids developed here hold great significance in maize biofortification programme.
迄今为止，玉米蛋白质质量的提高一直基于隐性不透明 2 号（o2）突变体，该突变体与胚乳修饰剂一起导致了优质蛋白玉米（QPM）的发展。最近发现隐性不透明 16 号（o16）突变体的营养价值具有重要意义，可进一步提高蛋白质质量。本研究利用标记辅助回交育种，将 o16 导入印度四个商业 QPM 杂交种（HQPM-1、HQPM-4、HQPM-5 和 HQPM-7）的基于 o2 的亲本自交系（HKI161、HKI193-1、HKI193-2 和 HKI163）中。背景选择导致轮回亲本基因组（RPG）的高回收率，最高可达 95%，导入的后代在植物、穗和籽粒特征方面与各自的轮回亲本具有相当大的表型相似性。o2 和 o16 标记的选择导致了金字塔系（o2o2/o16o16）的发展，这些系的赖氨酸和色氨酸含量分别比轮回亲本高出 76%和 91%。重组杂交种的赖氨酸和色氨酸平均比原始杂交种提高了 49%和 60%，最高提高了 64%和 86%。这是首次报道 o16 在适应亚热带的玉米基因型中提高赖氨酸和色氨酸的报道。在金字塔系中也观察到赖氨酸和色氨酸的适度变异。重组杂交种的多点评估显示，其籽粒产量和归因性状与原始版本相似。这项研究标志着 o16 作为 o2 的补充，在提高玉米的营养品质方面的作用，以及这里开发的改良自交系和杂交种在玉米生物强化计划中具有重要意义。
