Is there a strategy I iron uptake mechanism in maize?

The elite maize hybrid Zhengdan 958 (ZD958), which has high and stable yield and extensive adaptability, is widely grown in China. To elucidate the genetic basis of yield and its related traits in this elite hybrid, a set of doubled haploid (DH) lines derived from ZD958 were evaluated in four different environments at two locations over two years, and a total of 49 quantitative trait loci (QTL) and 24 pairs of epistatic interactions related to yield and yield components were detected. Furthermore, 21 QTL for six investigated phenotypic traits were detected across two different sites. Combining the results of these QTL in each environment and across both sites, three main QTL hotspots were found in chromosomal bins 2.02, 2.05-2.06, and 6.05 between the simple sequence repeat (SSR) markers umc1165-bnlg1017, umc1065-umc1637, and nc012-bnlg345, respectively. The existence of three QTL hotspots associated with various traits across multiple environments could be explained by pleiotropic QTL or multiple tightly linked QTL. These genetic regions could provide targets for genetic improvement, fine mapping, and marker-assisted selection in future studies. Maize is one of the most important food and feed crops in the world and plays an important role in ensuring food security. In maize breeding, increasing grain yield is the primary objective. Because grain yield is a complex quantitative trait controlled by multiple quantitative trait loci (QTL) with small effects that are affected by significant genotype-by-environment (G × E) interactions 1-3 , the heritability of grain yield is usually lower than those of other traits, such as plant height, ear height, ear length (EL), ear row number (ERN), and 100 kernel weight (HKW) 4-7. A low heritability indicates that a trait is affected by not only genotype but also G × E interactions 8. Thus, multi-environment trials are necessary to reach reliable conclusions. In previous studies, EL, ERN, HKW, ear diameter (ED), kernel number per row (KNR), kernel percentage (KP), and kernel weight per ear (KWE) were proven to be important yield components in maize, and these traits were positively correlated with grain yield 6,9-11. Yield components usually have higher heritabilities; for example, in the study of Flint-Garcia et al. 8 , the heritabilities of ERN and EL were 90.5% and 87.2%, respectively, whereas the heritability of grain yield was only 83.7%. In another study, the heritability of grain yield (81%) was also lower than those of its components KNR, EL, and HKW (91%, 86%, and 84%, respectively) 12. Ma et al. 5 also found that grain yield had the lowest broad-sense heritability of 77.4% compared to its three components ERN (88.2%), EL (84.6%), and HKW (84.9%). Thus, selection for yield components could be more effective than direct selection for grain yield itself. QTL mapping has been widely used to detect the genetic basis underlying yield components in maize 4,9,13-16 , and multiple QTL for grain yield components have been detected, but most of them made minor contributions to ...

Section: Discussionmentioning

confidence: 99%

Mapping of QTL for Grain Yield Components Based on a DH Population in Maize

Yang

Liu

Chen

et al. 2020

“…6). Expression profiles of genes related to Strategy I ( ZmIRT1 28 , ZmFIT1 29 and ZmMHA2 29 ) were evaluated. ZmFIT1 , orthologous to the transcription factor AtFIT , which regulates the expression of FRO2 and IRT1 in Arabidopsis 30 , was up-regulated in roots under −Fe (Fig.…”

Section: Resultsmentioning

confidence: 99%

The Combined Strategy for iron uptake is not exclusive to domesticated rice (Oryza sativa)

Wairich

Oliveira

Arend

et al. 2019

Iron (Fe) is an essential micronutrient that is frequently inaccessible to plants. Rice (Oryza sativa L.) plants employ the Combined Strategy for Fe uptake, which is composed by all features of Strategy II, common to all Poaceae species, and some features of Strategy I, common to non-Poaceae species. To understand the evolution of Fe uptake mechanisms, we analyzed the root transcriptomic response to Fe deficiency in O. sativa and its wild progenitor O. rufipogon. We identified 622 and 2,017 differentially expressed genes in O. sativa and O. rufipogon, respectively. Among the genes up-regulated in both species, we found Fe transporters associated with Strategy I, such as IRT1, IRT2 and NRAMP1; and genes associated with Strategy II, such as YSL15 and IRO2. In order to evaluate the conservation of these Strategies among other Poaceae, we identified the orthologs of these genes in nine species from the Oryza genus, maize and sorghum, and evaluated their expression profile in response to low Fe condition. Our results indicate that the Combined Strategy is not specific to O. sativa as previously proposed, but also present in species of the Oryza genus closely related to domesticated rice, and originated around the same time the AA genome lineage within Oryza diversified. Therefore, adaptation to Fe2+ acquisition via IRT1 in flooded soils precedes O. sativa domestication.

“…Roots of Strategy I plants have been described to exude metabolites such as phenolics that may play a role in Fe uptake by acting as reducing and/or chelating agents 5 , whilst Fe-starved Strategy II species such as rice and maize have been observed to induce IRT-encoding genes 6 – 8 . For this reason, a combined strategy has been recently postulated for the uptake of this micronutrient by grass species 8 , 9 .…”

Section: Introductionmentioning

confidence: 99%

Changes in physiological activities and root exudation profile of two grapevine rootstocks reveal common and specific strategies for Fe acquisition

Marastoni

Lucini

Miras-Moreno

et al. 2020

In several cultivation areas, grapevine can suffer from Fe chlorosis due to the calcareous and alkaline nature of soils. This plant species has been described to cope with Fe deficiency by activating Strategy I mechanisms, hence increasing root H+ extrusion and ferric-chelate reductase activity. The degree of tolerance exhibited by the rootstocks has been reported to depend on both reactions, but to date, little emphasis has been given to the role played by root exudate extrusion. We studied the behaviour of two hydroponically-grown, tolerant grapevine rootstocks (Ramsey and 140R) in response to Fe deficiency. Under these experimental conditions, the two varieties displayed differences in their ability to modulate morpho-physiological parameters, root acidification and ferric chelate reductase activity. The metabolic profiling of root exudates revealed common strategies for Fe acquisition, including ones targeted at reducing microbial competition for this micronutrient by limiting the exudation of amino acids and sugars and increasing instead that of Fe(III)-reducing compounds. Other modifications in exudate composition hint that the two rootstocks cope with Fe shortage via specific adjustments of their exudation patterns. Furthermore, the presence of 3-hydroxymugenic acid in these compounds suggests that the responses of grapevine to Fe availability are rather diverse and much more complex than those usually described for Strategy I plants.