Mexican native maize and highland/acid-soil adapted inbreds
Indigenous people domesticated maize more than 9,000 years ago in a hot,
dry, low-elevation region of southwest Mexico. Subsequently, maize dispersed
and was successfully established in different environments throughout the
Americas and, eventually, across the world. In Mexico alone, 59 different
native landraces of maize have been described, cultivated from sea level to
an elevation of 3400masl. Mexican highland varieties have adapted to a suite
of challenges, including low atmospheric pressure and temperature, frequent
frosts and freeze-thaw cycles, high UV-B radiation, seasonal precipitation,
and low bioavailability of phosphorus due to the low pH of volcanic soils.
Highland maize has to mature and complete grain filling before the first
frosts at the end of the growing season. To maximize the length of the
growing season, highland farmers sow early, before the onset of the annual
rains. Traditionally, seeds are deep planted (10 - 25 cm) to access residual
soil moisture and to protect from frost damage. This practice allows
varieties that require 160-180 days to reach maturity in the cold of the
highlands to be grown in areas with a frost-free season of 90-120 days.
Although displaying enhanced phosphorus use efficiency, Mexican highland
varieties tend to show restricted root development and, to prevent lodging,
plants are hilled (piling of soil around the base of the plant) during
vegetative growth.
To support broader efforts characterizing local adaptation in traditional
maize varieties, this project presents genome assemblies of the Mexican
highland varieties Palomero Toluqueño (collected at 2507masl) and Palomero
de Jalisco (2520masl), the Mexican mid-elevation variety Tabloncillo (1355m),
the lowland variety Zapalote Chico (50masl), and the CIMMYT inbred lines
CML457 and CML459 (highland adaptation) and CML530 (acid soil adaptation)
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This project was supported by NSF Award
#1546719
and collaboration with CINVESTAV Unidad de Genómica Avanzada (LANGEBIO),
Universidad Nacional Autónoma de México (UNAM), North Carolina State
University, Iowa State University, UC Davis, Penn State University,
USDA-ARS and Corteva Agriscience. We acknowledge the smallholder farmers
and indigenous people of the Americas whose work and love for their
traditions and identity keep maize genetic variation alive.
References
Eagles HA, Lothrop JE (1994) Highland Maize from Central Mexico - Its
Origin, Characteristics, and Use in Breeding Programs. Crop Science 34: 11–19
doi: cropsci1994.0011183X003400010002x
Perez-Limón S, Li M, Cintora-Martinez GC, Aguilar-Rangel MR,
Salazar-Vidal MN, González-Segovia E, Blöcher-Juárez K, Guerrero-Zavala A,
Barrales-Gamez B, Carcaño-Macias J, et al (2022) A B73×Palomero Toluqueño
mapping population reveals local adaptation in Mexican highland maize. G3
(Bethesda).
doi: 10.1093/g3journal/jkab447
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