Hossain Firoz, Muthusamy Vignesh, Pandey Neha, Vishwakarma Ashish K, Baveja Aanchal, Zunjare Rajkumar U, Thirunavukkarasu Nepolean, Saha Supradip, Manjaiah Kanchikeri M Manjaiah, Prasanna Boddupalli M, Gupta Hari S
ICAR-Indian Agricultural Research Institute (IARI), New Delhi 110 012, India.
J Genet. 2018 Mar;97(1):287-298.
Maize is a valuable source of food and feed worldwide. Maize endosperm protein is, however nutritionally poor due to the reduced levels of two essential amino acids, lysine and tryptophan. In this study, recessive opaque2 (o2) allele that confers enhanced endosperm lysine and tryptophan, was introgressed using marker-assisted backcross breeding into three normal inbred lines (HKI323, HKI1105 and HKI1128). These are the parental lines of three popular medium-maturing single cross hybrids (HM4, HM8 and HM9) in India. Gene-based simple sequence repeat (SSR) markers (umc1066 and phi057) were successfully deployed for introgression of o2 allele. Background selection using genome-based SSRs helped in recovering > 96% of recurrent parent genome. The newly developed quality protein maize (QPM) inbreds showed modified kernels (25-50% opaqueness) coupled with high degree of phenotypic resemblance to the respective recipient lines, including grain yield. In addition, endosperm protein quality showed increased lysine and tryptophan in the inbreds to the range of 52-95% and 47-118%, respectively. The reconstituted QPM hybrids recorded significant enhancement of endosperm lysine (48-74%) and tryptophan (55-100%) in the endosperm. The QPM hybrids exhibited high phenotypic similarity with the original hybrids for morphological and yield contributing traits along with responses to some major diseases like turcicum leaf blight and maydis leaf blight. The grain yield of QPM hybrids was at par with their original versions under multilocation testing. These elite, high-yielding QPM hybrids with improved protein quality have been released and notified for commercial cultivation, and hold significant promise for improving nutritional security.
玉米是全球重要的食物和饲料来源。然而，玉米胚乳蛋白的营养价值较低，因为其中两种必需氨基酸——赖氨酸和色氨酸的含量较低。在本研究中，利用标记辅助回交育种将赋予胚乳赖氨酸和色氨酸含量增加的隐性不透明2（o2）等位基因导入三个普通自交系（HKI323、HKI1105和HKI1128）。这些是印度三种流行的中熟单交杂种（HM4、HM8和HM9）的亲本系。基于基因的简单序列重复（SSR）标记（umc1066和phi057）成功用于o2等位基因的导入。使用基于基因组的SSR进行背景选择有助于恢复超过96%的轮回亲本基因组。新培育的优质蛋白玉米（QPM）自交系表现出改良的籽粒（25%-50%不透明），并且在包括籽粒产量在内的各个方面与相应的受体系具有高度的表型相似性。此外，自交系胚乳蛋白质量显示，赖氨酸和色氨酸含量分别增加到52%-95%和47%-118%。重新构建的QPM杂种在胚乳中赖氨酸（48%-74%）和色氨酸（55%-100%）含量显著提高。QPM杂种在形态和产量相关性状以及对一些主要病害如大斑病和小斑病的反应方面与原始杂种表现出高度的表型相似性。在多点试验中，QPM杂种的籽粒产量与原始杂种相当。这些具有改良蛋白质质量的优质、高产QPM杂种已被发布并批准用于商业种植，对改善营养安全具有重要意义。
