Multiple genetic loci for zinc uptake and distribution in barley (Hordeum vulgare)

Abstract

Summary• Micronutrient malnutrition, often called 'hidden hunger', affects over two billion people globally. This is particularly problematic in developing countries where widespread zinc (Zn) deficiency exists as a result of a predominantly plant-based diet. Furthermore, supplemental fertilizers are often unavailable or unaffordable in impoverished regions where soil infertility is common. Delivery of more Zn via food grains is theoretically possible through selective breeding strategies, but severe technical difficulties associated with trace element research have limited research on the underlying genetic components of Zn nutrition.• Genetic dissection of Zn nutrition involved a pre-existing doubled haploid mapping population of barley (Hordeum vulgare). Association of mineral nutrient accumulation traits with regions of the barley genome was determined in two seasons of growth to maturity, using MAPMANAGER QTX and QGENE 4.0.• Nine genetic loci segregating in the population associated clearly with measured traits, including five that contributed to grain Zn status. Pooling two-row doubled haploids by selecting the three most favourable alleles increased grain Zn content and concentration by an average of 53 and 75%, respectively.• These results will inform breeding efforts for increased Zn density in the major food grain, wheat (Triticum aestivum), by enabling syntenic marker-assisted selection in conventional breeding programmes.

Wheat-Aegilops chromosome addition lines showing high iron and zinc contents in grains

“…Schlegel et al (1998) pointed out that chromosomes L1, L4 and L7 of Agropyron intermedium and chromosomes V2 and V7 of Haynaldia villosa have the effects on enhancing of Zn efficiency. In barley, genes that control grain Zn concentrations are located on chromosomes 2H and 5H (Lonergan et al 2009). Distelfeld et al (2007), Uauy et al (2006) and Waters et al (2009) reported that the Gpc-B1 (TtNAM-B1) gene which are located on 6BS, are involved in more efficient remobilization of Zn and Fe from leaves to grain.…”

Improved yield and Zn accumulation for rice grain by Zn fertilization and optimized water management

“…However, zinc (Zn) deficiency in rice has been widely reported in many rice-growing regions of the world (Lonergan et al, 2009;Tiong et al, 2014). Zn deficiency in crop plants results in not only yield reduction but also Zn malnutrition in humans, where a high proportion of rice is consumed as a staple food (Wu et al, 2011;Chasapis et al, 2012).…”

Nutritionally Enhanced Staple Food Crops

“…Further work at ICRISAT is in progress to identify genetically diverse germplasm (noniniary type) from the recently constituted pearl millet mini-core collection (Upadhyaya et al 2010) for developing hybrid parental lines with high seed-Fe concentration. In a two-rowed barley, the pooling of three most favourable QTL alleles increased seed-Zn content and concentration by an average of 53% and 75%, respectively (Lonergan et al 2009). The AgroSalud project (www.AgroSalud.org), a consortium of centers from the CGIAR, NARS, Universities, and NGOs formed in 2005 with funding support from Canadian International Development Agency (CIDA), aims to improve food and nutrition security among vulnerable populations living in 14 Latin American and Caribbean countries through nutritionally enhanced biofortified crops (beans, maize, rice, sweet potato) and food products derived from these crops and cassava.…”

“…Other QTL were identified on LG B3, B6, B7, and B9 for zinc and B4, B6, B7, and B8 for iron Blair et al 2009a Fe: 11 QTLs on six LGs, 8%-36% variation; Zn: 11 QTLs on four LGs, 9%-39% variation; a QTL on LG B1 (nearest to fin marker) accounted 34% variation for Fe and Zn, while another QTL on LG B6 (nearest to AGAT05 marker) accounted 36%-39% variation for Fe and Zn Cichy et al 2009 A locus on LG9 associated with Zn accumulation Gelin et al 2007 Two QTL for Fe (25% variation) and one QTL for Zn (15% variation) (Stangoulis et al 2007). In Barley, specific markers have been developed for a high zinc QTL on chromosome 2H (Sadeghzadeh et al 2010), while other QTLs have been identified by Lonergan et al (2009). Iron reductases are members of the protein super-family of flavocytochromes and function in roots to convert Fe from a plant unavailable form (ferric, Fe 3þ ) to an available form (ferrous, Fe 2þ ) that can be readily absorbed (Grusak 1995).…”

“…Three of the five most favorable QTL alleles increased seed-Zn concentration and content by an average of 53% and 75%, respectively Lonergan et al 2009 Common bean…”