The U.S. Breeding Program to Develop Peanut with Drought Tolerance and Reduced Aflatoxin Contamination

Abstract

Aflatoxin contamination costs the U.S. peanut (Arachis hypogaea L.) industry over $20 million annually. The development of peanut cultivars with resistance to preharvest aflatoxin contamination (PAC) would reduce these costs. Screening techniques have been developed that can measure genetic differences in aflatoxin contamination and they have been used to identify accessions that exhibited relatively low PAC in multiple environments. Significant reductions in PAC have been identified in peanut genotypes with drought tolerance. These sources of resistance to PAC have been crossed with cultivars and breeding lines that have high yield, acceptable grade, and resistance to spotted wilt caused by Tomato spotted wilt tospovirus (TSWV). Due to the large environmental variation in PAC, breeding populations can only be evaluated in late generations when there is less heterozygosity and adequate numbers of seed are available for field testing using multiple replications. Evaluation of numerous breeding populations has identified several families and individual breeding lines with relatively low PAC, relatively high yield, and acceptable levels of resistance to TSWV. To increase breeding efficiency, studies on mechanisms of resistance to PAC are being conducted. The most promising mechanisms identified thus far are resistance to drought and resistance to the peanut rootknot nematode. Late generation breeding lines have been developed with resistance to drought, several of which also exhibited reduced aflatoxin contamination in multiple environments. Tifguard, the first cultivar with high levels of resistance to both TSWV and the peanut root-knot nematode [Meloidogyne arenaria (Neal) Chitwood race 1] was released from this program. Testing is ongoing to determine if this cultivar can be used to reduce aflatoxin contamination in nematode infested fields.

Oxidative stress and carbon metabolism influence Aspergillus flavus transcriptome composition and secondary metabolite production

“…However, a lack of diverse, resistant germplasm for aflatoxin contamination along with a high degree of environmental and genotype × environmental interaction influences on resistance has posed difficulties in breeding programs91011. Environmental stresses including drought and heat stress can exacerbate aflatoxin contamination in maize and peanut1213. This increase in aflatoxin contamination under drought stress in particular has motivated numerous research efforts endeavoring to address why A. flavus and other Aspergilli produce aflatoxin in stressed environments.…”

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

“…Nevertheless, a large scale screening effort consisting of 831 accessions in the US peanut core collection led to the identification of 19 accessions with low PAC and relatively high yield [86]. At the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) several resistant germplasms were identified for three types of resistance (i.e.…”

Identifying Aflatoxin Resistance-related Proteins/Genes through Proteomics and RNAi Gene Silencing1

“…Promising sources of resistant peanut germplasm have also been identified from a core germplasm collection, although resistance screening has proven to be a difficult task with this crop (Holbrook et al, 2008). These peanut lines, however, have less than acceptable agronomic characteristics, and are thus being hybridized with commercially acceptable lines.…”