Division of Genetics, ICAR-Indian Agricultural Research Institute, New Delhi, India.
CCS-Haryana Agricultural University, Regional Research Station, Uchani, Haryana, India.
PLoS One. 2021 Feb 4;16(2):e0245497. doi: 10.1371/journal.pone.0245497. eCollection 2021.
Malnutrition has emerged as one of the major health problems worldwide. Traditional yellow maize has low provitamin-A (proA) content and its genetic base in proA biofortification breeding program of subtropics is extremely narrow. To diversify the proA rich germplasm, 10 elite low proA inbreds were crossed with a proA rich donor (HP702-22) having mutant crtRB1 gene. The F2 populations derived from these crosses were genotyped using InDel marker specific to crtRB1. Severe marker segregation distortion was observed. Seventeen crtRB1 inbreds developed through marker-assisted pedigree breeding and seven inbreds generated using marker-assisted backcross breeding were characterized using 77 SSRs. Wide variation in gene diversity (0.08 to 0.79) and dissimilarity coefficient (0.28 to 0.84) was observed. The inbreds were grouped into three major clusters depicting the existing genetic diversity. The crtRB1-based inbreds possessed high β-carotene (BC: 8.72μg/g), β-cryptoxanthin (BCX: 4.58μg/g) and proA (11.01μg/g), while it was 2.35μg/g, 1.24μg/g and 2.97μg/g in checks, respectively. Based on their genetic relationships, 15 newly developed crtRB1-based inbreds were crossed with five testers (having crtRB1 gene) using line × tester mating design. 75 experimental hybrids with crtRB1 gene were evaluated over three locations. These experimental hybrids possessed higher BC (8.02μg/g), BCX (4.69μg/g), proA (10.37μg/g) compared to traditional hybrids used as check (BC: 2.36 μg/g, BCX: 1.53μg/g, proA: 3.13μg/g). Environment and genotypes × environment interaction had minor effects on proA content. Both additive and dominance gene action were significant for proA. The mean proportion of proA to total carotenoids (TC) was 44% among crtRB1-based hybrids, while 11% in traditional hybrids. BC was found to be positively correlated with BCX (r = 0.68) and proA (r = 0.98). However, no correlation was observed between proA and grain yield. Several hybrids with >10.0 t/ha grain yield with proA content >10.0 μg/g were identified. This is the first comprehensive study on development of diverse proA rich maize hybrids through marker-assisted pedigree breeding approach. The findings provides sustainable and cost-effective solution to alleviate vitamin-A deficiency.
营养不良已成为全球主要的健康问题之一。传统的黄色玉米维生素 A 含量低，其在亚热带地区的 proA 生物强化育种计划中的遗传基础极为狭窄。为了使富含 proA 的种质多样化，10 个 elite 低 proA 自交系与具有突变 crtRB1 基因的富含 proA 的供体（HP702-22）杂交。利用针对 crtRB1 的 InDel 标记对这些杂交的 F2 群体进行基因型分析。观察到严重的标记分离偏倚。通过标记辅助系谱育种开发了 17 个 crtRB1 自交系，通过标记辅助回交育种开发了 7 个自交系，并使用 77 个 SSR 进行了表征。观察到基因多样性（0.08 至 0.79）和相异系数（0.28 至 0.84）的广泛变化。将自交系分为三个主要聚类，描绘了现有的遗传多样性。基于 crtRB1 的自交系具有高 β-胡萝卜素（BC：8.72μg/g），β-隐黄质（BCX：4.58μg/g）和 proA（11.01μg/g），而对照品中分别为 2.35μg/g，1.24μg/g和 2.97μg/g。基于其遗传关系，用 5 个测试者（具有 crtRB1 基因）对线×测试者交配设计对 15 个新开发的基于 crtRB1 的自交系进行了杂交。在三个地点评估了 75 个具有 crtRB1 基因的实验杂种。这些实验杂种的 BC（8.02μg/g），BCX（4.69μg/g），proA（10.37μg/g）含量均高于传统杂种（BC：2.36μg/g，BCX：1.53μg/g，proA：3.13μg/g）。环境和基因型×环境互作对 proA 含量的影响较小。 proA 既具有加性基因作用，又具有显性基因作用。基于 crtRB1 的杂种中 proA 与总类胡萝卜素（TC）的平均比例为 44％，而传统杂种中为 11％。 BC 与 BCX（r = 0.68）和 proA（r = 0.98）呈正相关。但是，在 proA 和谷物产量之间未观察到相关性。鉴定出了一些具有> 10.0 t/ha 谷物产量和> 10.0μg/g proA 含量的杂种。这是首次通过基于标记的系谱育种方法开发富含多种 proA 的玉米杂种的综合研究。研究结果为缓解维生素 A 缺乏症提供了可持续且具有成本效益的解决方案。
