Identification of Zinc Efficiency-Associated Loci (ZEALs) and Candidate Genes for Zn Deficiency Tolerance of Two Recombination Inbred Line Populations in Maize

Abstract

Zinc (Zn) deficiency is one of the most common micronutrient disorders in cereal plants, greatly impairing crop productivity and nutritional quality. Identifying the genes associated with Zn deficiency tolerance is the basis for understanding the genetic mechanism conferring tolerance. In this study, the K22×BY815 and DAN340×K22 recombination inbred line (RIL) populations, which were derived from Zn-inefficient and Zn-efficient inbred lines, were utilized to detect the quantitative trait loci (QTLs) associated with Zn deficiency tolerance and to further identify candidate genes within these loci. The BLUP (Best Linear Unbiased Prediction) values under Zn-deficient condition (-Zn) and the ratios of the BLUP values under Zn deficient condition to the BLUP values under Zn-sufficient condition (-Zn/CK) were used to perform linkage mapping. In QTL analysis, 21 QTLs and 33 QTLs controlling the Zn score, plant height, shoot and root dry weight, and root-to-shoot ratio were detected in the K22×BY815 population and the DAN340×K22 population, explaining 5.5–16.6% and 4.2–23.3% of phenotypic variation, respectively. In addition, seventeen candidate genes associated with the mechanisms underlying Zn deficiency tolerance were identified in QTL colocalizations or the single loci, including the genes involved in the uptake, transport, and redistribution of Zn (ZmIRT1, ZmHMAs, ZmNRAMP6, ZmVIT, ZmNAS3, ZmDMAS1, ZmTOM3), and the genes participating in the auxin and ethylene signal pathways (ZmAFBs, ZmIAA17, ZmETR, ZmEIN2, ZmEIN3, ZmCTR3, ZmEBF1). Our findings will broaden the understanding of the genetic structure of the tolerance to Zn deficiency in maize.

Quantitative trait loci and candidate genes for iron and zinc bio-fortification in genetically diverse germplasm of maize (Zea mays L): A systematic review

“…On chromosomes 6, 9, and 10, four QTLs for Zn score were found (qkb-ZnSc6-1, QB-ZnSc9-1, qKB-ZnSc9-2, qKB-ZnSc10-1). At these four mapped loci, alleles from By815, the Zn-efficient parent, displayed increasing effects (0.15–0.19) on the Zn score [ 22 , 23 ]. Together, SYN11817 and PZE-106098680 bordered qKB-ZnSc6-1 on chromosome 6, and together they explained 9.2% of the variation [ 22 ].…”

“…At these four mapped loci, alleles from By815, the Zn-efficient parent, displayed increasing effects (0.15–0.19) on the Zn score [ 22 , 23 ]. Together, SYN11817 and PZE-106098680 bordered qKB-ZnSc6-1 on chromosome 6, and together they explained 9.2% of the variation [ 22 ]. On chromosome 9, the genes qKB-ZnSc9-1 and qKB-ZnSc9-2 were discovered in the PZE-109025227-PZE109051633 intervals [ 12 , 23 , 50 , 55 ].…”

“…The total maize production in the world is 1,162 million tons (in 2020) growing at an average annual rate of 3.07% and consumption per day in the world is approximately 49 g, which occupies the third position after wheat (179) and rice (148) [ 7 , 20 , 21 ] Maize is cultivated on around 236 million hectares in more than 165 countries in the world, so it acts as a powerful energy improvement channel through a transgenic biofortification approach [ 2 , 22 ]. Biofortification is the emerging technology that is essential for proper marking of which candidate genes are involved in nutrient accumulation in crops [ 3 , 23 ] Maize is also called the queen of cereals because it has high productivity and nutrient qualities as well as quantity due to its genetic potential and contributes 39% to global grain production [ 24 ].…”

“… Biofortified maize cultivars Name of the country Collaboration with Superior % of Zn than other varieties. References 1 ICTA HB-18 and ICTA B-15 Guatemala CIMMYT- CGIAR- ICTA-Harvest Plus ICTA HB-18 > 15% ICTA B-15 > 60% Zn > tortillas [ 17 , 29 ] 2 BIO-MZN01 Colombia CIMMYT-Harvest Plus 36% > other [ 10 , 17 , 22 ] …”

“…More than 4.5 billion people in 94 developing nations receive at least 30% of their daily calories from maize, along with rice and wheat [ 48 ]. They include the 900 million underprivileged people who favor maize as a staple food [ 22 ]. Approximately to 27percent of worldwide people suffer from iron deficiency anemia (IDA), and over 1.1 billion people are in danger of zinc (Zn) insufficiency [ 49 ].…”