Registration of Maize Germplasm Lines Tx736, Tx739, and Tx740 for Reducing Preharvest Aflatoxin Accumulation

Abstract

Maize (Zea mays L.) production in Texas, the southern United States, and much of the developing world is constrained by preharvest contamination from aflatoxins—potent mycotoxins produced by the fungus Aspergillus flavus. When consumed, aflatoxin can lead to impaired growth, liver cancer, or death of both humans and livestock. Because of these effects, the presence of this mycotoxin is tightly regulated in the U.S. food supply. No complete resistance to A. flavus or aflatoxin is known to exist in maize; however, multiple quantitative traits and some sources of resistance have been identified. We propose the release of three maize lines that demonstrate reduced preharvest aflatoxin accumulation. Tx736 (Reg. No. GP‐578, PI 662937) is a germplasm line derived from modified pedigree selection of a cross between Tx772, a line with reduced aflatoxin accumulation, and T246, a temperate line with good yield and Texas adaptation, backcrossed to Tx772 once. Lines Tx739 (Reg. No. GP‐579, PI 662938) and Tx740 (Reg. No. GP‐580, PI 662939) were selected by pedigree methods from S3 plants selfed out of heterotic groups A, C, and E from Agricomseeds (Santa Cruz, Bolivia). These three lines were field tested as lines per se and as testcross hybrids with introduced inoculation in multienvironmental field trials. In trials, these lines and hybrids had between 30 and 73% lower aflatoxin content than commercial checks. These germplasm lines will serve as unique sources for novel traits and alleles that reduce aflatoxin in elite temperate and subtropical maize.

Aflatoxin Resistance in Maize: What Have We Learned Lately?

“…Because of the highly quantitative nature of host plant genetic resistance to A. flavus infection and aflatoxin accumulation in maize, it has been very difficult to transfer the resistance from these older breeding lines into a more agronomically acceptable idiotype using only phenotypic selection. However, some of the newest breeding lines including Mp718, Mp719, Tx736, Tx739, and Tx740 [29,30] that have recently been released show a much better plant type and high resistance.…”

Unoccupied aerial system enabled functional modeling of maize (Zea mays L.) height reveals dynamic expression of loci associated to temporal growth

“…The recombinant inbred line (RIL) progeny were derived from the crosses of Tx740xNC356 (tropical/tropical; 110 RILs), Ki3xNC356 (tropical/tropical; 239 RILs) and LH82xLAMA-YC (temperate/tropical; 178 RILs). Tx740 (LAMA2002-12-1-B-B-B) [58] is a parent in the “LAMA” inbred line (pedigree [((LAMA2002-12-1-B-B-B-B/LAMA2002-1-5-B-B-B-B)-3-2-B-1-B3-B]) and these two lines would be expected to share 50% of their genome. In 2018, the mapping populations were planted in a randomized complete block design (RCBD) with two replications across two environments (irrigated and non-irrigated) having dimensions of 0.76 m row spacing, and 3.81 m plot lengths.…”

Mapping Quantitative Trait Loci Associated With Resistance to Aflatoxin Accumulation in Maize Inbred Mp719

“…Early breeding efforts identified A. flavusresistant inbred lines Mp420 and Mp313E Zummo, 1990, 1992). Additional germplasm lines developed for resistance to aflatoxin accumulation included GT-601-GT-603 developed from the GT-MAS:gk population, and Mp715, Mp717-Mp719, Tx736, Tx739, Tx740, Tx772, TZAR101-TZAR106 (McMillian et al, 1993;Williams and Windham, 2001Llorente et al, 2004;Guo et al, 2007Guo et al, , 2011Menkir et al, 2008;Mayfield et al, 2012). Despite steady development of genetic sources of resistance to aflatoxin accumulation in maize germplasm, attempts to transfer resistance to more agronomically adequate hybrids have been challenging (Abbas et al, 2002;Warburton and Williams, 2014).…”