Sources of Resistance in Maize to Kernel Infection by Aspergillus flavus in the Field

Abstract

Infection of maize, Zea mays L., kernels by Aspergillus flavus Link ex Fr. and subsequent aflatoxin production can be an extremely serious problem; especially in maize grown in the southeastern part of the USA. Maize genotypes that resist attack by this fungus are desperately needed. The objective of these studies was to identify maize inbreds with resistance to kernel infection by A. flavus. Inbreds were inoculated with a pinbar and evaluated for percentage of kernels internally infected by this fungus. Nearly a 5‐fold difference (6 to 30%) among the inbreds tested over a 2‐yr period was found. Five of the inbreds selected as resistant, and five as susceptible, were subsequently tested using a pinbar and two needle inoculation techniques. The pinbar inoculation technique gave the highest level of kernel infection and the greatest separation of the inbreds into their previously classified groups, but all methods of inoculation showed that the two groups of inbreds differed significantly from each other. In a test with 50 inbreds inoculated by the side‐needle inoculation technique, percentage of A. flavus infected kernels ranged from 4 to 62. Resistant (Mp313E, SC54, and Mo18W) and susceptible (T202, T216, and SC212M) inbreds averaged 10 and 44% infected kernels, respectively.

Development of Maize Host Resistance to Aflatoxigenic Fungi

“…Two resistant inbreds (Mp420 and Mp313E) were discovered and tested in field trials at different locations and released as sources of resistant germplasm [11,19]. The pinbar inoculation technique was one of the methods employed in the initial trials, and contributed towards the separation of resistant from susceptible lines [11].…”

“…The pinbar inoculation technique was one of the methods employed in the initial trials, and contributed towards the separation of resistant from susceptible lines [11]. Several other inbreds, demonstrating resistance to aflatoxin contamination in Illinois field trials (employing a modified pinbar technique) also were discovered [12].…”

“…The approach to enhance host resistance through breeding gained renewed attention following the discovery of natural resistance to A. flavus infection and aflatoxin production in Maize [8][9][10][11][12]. While several resistant maize genotypes have useful for effective resistance breeding.…”

Using biotechnology to enhance host resistance to aflatoxin contamination of corn

“…Inoculation methods employed with corn include the pinbar inoculation technique (for inoculating kernels through husks with A. flavus conidia), the silk inoculation technique, and infesting corn ears with insect larvae infected with A. flavus conidia (King and Scott, 1982;Tucker et al, 1986). Two resistant inbreds (Mp420 and Mp313E) (Scott and Zummo, 1988;Windham and Williams, 1998) were discovered and tested in field trials at different locations, using the pin-bar technique, and released as sources of resistant germplasm.…”

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

“…The approach to enhance host resistance through conventional breeding and/or genetic engineering has gained renewed attention following the discovery of natural resistance to A. flavus infection and aflatoxin production in maize (Gardner et al, 1987;King and Scott, 1982;Widstrom et al, 1987;Scott and Zummo, 1988;White, 1995, Brown et al, 1995;Brown et al, 1999). 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).…”