This document outlines objectives to validate genes associated with aluminum tolerance quantitative trait loci (QTLs), specifically ZmMATE genes, in maize crosses from Brazil and Kenya. It identifies ZmMATE1 as a candidate gene for aluminum tolerance in maize that encodes a transporter for citrate exudation from roots. Studies found higher ZmMATE1 expression and aluminum tolerance in lines with three copies of the gene. The objectives are to develop molecular tools like flanking markers for marker-assisted selection of the QTL, and to characterize and distribute genetic materials with improved aluminum tolerance. Key products include characterized germplasm, flanking markers, and capacity building activities.

1. Embrapa Maize & Sorghum
Jurandir Vieira Magalhães
Lauro Guimarães
Maria Marta Pastina
Sidney Netto Parentoni
Ubiraci Gomes P. Lana
Vera Maria Carvalho Alves
Christiano Simões
Renato Vasconcellos
Carlos Fasane Tinoco
USDA-ARS/Cornell
University - USA
Leon Kochian
Lyza Maron
Miguel Piñeros
Ed Buckler
Moi University Kenya
Samuel Gudu
Beatrice Were
Evans Ouma
Thomas Matonyei
KARI, Kitale Kenya
Dickson Ligeyo
Validation of ZmMATEs as Genes Underlying
Major Al Tolerance QTLs in Maize
G7010.03.02
Claudia Guimarães
claudia.guimaraes@embrapa.br

2. Tropical Acid Soils
High Al toxicity;
low P availability
Low sustainability for
crop production in 48%
of world arable land
Represent:
205 millions ha, mostly arable lands in Brazil
7.5 millions ha in Kenya, coincident with maize growing areas
Acid soilsMaize growing areas

3. Objectives
Objective 1: Validation of functional ZmMATE or Al
tolerance QTLs in Brazilian maize crosses
Objective 2: Validation of ZmMATE genes or Al
tolerance QTLs in a panel of Kenyan and Brazilian
maize lines
Objective 3: Development of molecular tools for
markers assisted introgression of ZmMATE genes or Al
tolerance QTLs

4. ZmMATE1: Candidate Gene for Al Tolerance
in Maize
Maron et al. 2010 Plant Journal
61: 728–740
• Homologue to SbMATE
• Co-localizes to the qALT6
• High expression in root tips of
Al-tolerant line under Al stress
• Mediates citrate exudation
• Improve Al tolerance and
induces citrate exudation
intransgenic Arabidopsis

5. High ZmMATE1 expression is associated with
three copies of the target gene
Maron et al. 2013. PNAS 110 (13): 5241-46
• qALT6 co-localizes with eQTL
for ZmMATE1 expression
• Three copy-number variation:
improve ZmMATE1 expression
and Al tolerance in RILs and NILs
• Rare CNV: two Cateto lines and
IL677 – maize diversity panel
Three copies of ZmMATE1 in tandem: Cateto Al237

6. Molecular Tools for Marker-Assisted
Introgression of qALT6 – ZmMATE1
• Source of high ZmMATE1 expression in adapted lines from
Brazil and Kenya:
• Kenya: CatetoAl237xL3-5, SynAlxR12C10-8,
SynAlxAO89xAO89-40 and ATPS4SynxR12C10-5
• Brazil: Cateto Al237, L228-3, 521236, 521237
• Flanking markers for qATL6:
• umc1018 and ZmMATE1 have been used to introgress
qATL6 in maize NILs and other maize elite lines from
Brazil;
• SNPs PZA00606_4 located at 2.4 Mbp and
PHM15961_13 at 9.7 Mbp on maize chromosome 6:
molecular data available at IBP
• Markers along maize genome: 1085 polymorphic SNPs
among 38 Kenyan and 48 Brazilian lines: molecular data
available at IBP

7. Key Products
1. Genetic materials developed and characterized for Al tolerance,
ZmMATE1 expression and CNV, grain yield: RILs, NILs and near-
isogenic hybrids introgressed with qALT6, Kenyan and Brazilian
maize lines
2. Flanking markers for ZmMATE1: two flanking markers of qATL6
in Brazilian germplasm and two SNP markers genotyped in
Kenyan and Brazilian lines.
3. Polymorphic SNP markers randomly distributed in maize
genome. They can be easily selected in the IBP and used to
recovery the recurrent genetic background in MABC programs.
4. ZmMATE1 validated for Al tolerance in maize: ZmMATE1 as a
target region to improve Al tolerance and yield stability in maize.

8. Additional Products
• Capacity building:
• One PhD student from Kenya trained at Embrapa
• One PhD and one MS student from Brazil
• Two undergraduate students
• Publications:
• Book chapters: three
• Papers: two published; one almost submitted
• Several internal technical documents: Embrapa
• Abstracts.
• Future perspective to continue the ZmMATE1 study in a broad
range of tropical and subtropical CIMMYT lines: collaboration
with Raman Babu, CIMMYT - Hyderabad.