Identifying and developing maize germplasm with resistance to accumulation of aflatoxins

Abstract

Efforts to identify maize germplasm with resistance to Aspergillus flavus infection and subsequent accumulation of aflatoxins were initiated by the US Department of Agriculture, Agricultural Research Service at several locations in the late 1970s and early 1980s. Research units at four locations in the south-eastern USA are currently engaged in identification and development of maize germplasm with resistance to A. flavus infection and accumulation of aflatoxins. The Corn Host Plant Resistance Research Unit, Mississippi State, MS, developed procedures for screening germplasm for resistance to A. flavus infection and accumulation of aflatoxins. Mp313E, released in 1990, was the first line released as a source of resistance to A. flavus infection. Subsequently, germplasm lines Mp420, Mp715, Mp717, Mp718, and Mp719 were released as additional sources of resistance. Quantitative trait loci associated with resistance have also been identified in four bi-parental populations. The Crop Protection and Management Research Unit and Crop Genetics and Breeding Research Unit, Tifton, GA, created a breeding population GT-MAS:gk. GT601, GT602, and GT603 were developed from GT-MAS:gk. The Food and Feed Safety Research Unit, New Orleans, LA, in collaboration with the International Institute for Tropical Agriculture used a kernel screening assay to screen germplasm and develop six germplasm lines with resistance to aflatoxins. The Plant Science Research Unit, Raleigh, NC, through the Germplasm Enhancement of Maize (GEM) Project provides to co-operators diverse germplasm that is a valuable source of resistance to A. flavus infection and accumulation of aflatoxins in maize.

Evaluation of African-Bred Maize Germplasm Lines for Resistance to Aflatoxin Accumulation

“…Fifty-six single-cross hybrids, the majority involving susceptible line T173, were evaluated for aflatoxin accumulation in a trial in 2013, and aflatoxin levels ranged from a high of 491 ng/g for NC334ˆT173 to a low of 1 ng/g for Mp313EˆMp494 (Table 3). The majority of the data in Table 3 was reported in a previous publication in a table that also reported aflatoxin values for inbreds that were crossed with T173 [18].The TZAR cross with the lowest numerical accumulation was TZAR106ˆT173 with 27 ng/g which was significantly different from NC334ˆT173, but not significantly different from crosses involving known resistant lines including Mp715 and Mp719. TZAR101ˆT173 also accumulated relatively low levels of aflatoxin (69 ng/g) and was not significantly different from TZAR106ˆT173.…”

Aflatoxin Accumulation in a Maize Diallel Cross

“…Three of the parental inbred lines were developed and released by USDA-ARS at Mississippi State as sources of resistance to A. flavus infection and aflatoxin accumulation: Mp313E, Mp717, and Mp719 [13,16,17]. Mp494, NC388, and CML322 had exhibited resistance, and Va35, T173, B73, and PHW79, susceptibility in field trials conducted at Mississippi State [12,18,20]. The 10 inbred lines were planted on 14 May 2013 and 21 April 2014 in a Leeper silty clay loam (fine, smectitic, non-acid, thermic Vertic Epiaquepts) soil at Mississippi State, MS.…”

“…Awareness of the serious consequences associated with pre-harvest aflatoxin contamination and the potential value of plant resistance in reducing losses to aflatoxin led to the establishment of several federally and state supported maize breeding programs in the southeastern USA to address the problem [12]. One such program was initiated by the U.S. Department of Agriculture's Agricultural Research Service at Mississippi State, Mississippi.…”

“…Five additional lines were released subsequently: Mp420, Mp715, Mp717, Mp718, and Mp719 [14][15][16][17]. In addition, other potential useful sources of resistance have been identified [12,18].…”

Resistance to Aspergillus flavus in maize and peanut: Molecular biology, breeding, environmental stress, and future perspectives

“…As recently reviewed by Williams et al [68], several aflatoxin resistant lines including GT601, GT602, GT603, Mp715, Mp717, Mp718, and Mp719 were derived from conventional breeding programs in the southeastern U.S. In addition, the incorporation of exotic lines with aflatoxin accumulation resistance and additional desirable traits into breeding programs to widen the genetic base of traditional temperate lines through cooperative efforts such as the Germplasm Enhancement of Maize (GEM) project will allow for further enhancement of previously identified resistant lines [68]. In addition to variety development, recent research has also focused on the evaluating the general and specific combining abilities of aflatoxin resistant lines to enhance hybrid development.…”