Responses to selection of S5 inbreds for broad-based resistance to ear rots and grain mycotoxin contamination caused by Fusarium spp. in maize

Abstract

Random S 5 inbreds derived from three F 2 maize (Zea mays L.) populations (L1934 9 LP918, LP915 9 LP2541 and L7310 9 L7266) were selected for ear rot resistance after inoculation with a lowfumonisin producing isolate belonging to F. proliferatum. The four less susceptible and the four most susceptible inbreds from each population were crossed and F 1 seeds were pooled. Resistant and susceptible pools from each population were evaluated for disease severity (percentage of the ear visibly diseased) after inoculation with the isolate used for selection, and high toxigenic isolates belonging to F. verticillioides and F. graminearum. Grain mycotoxin concentration was assessed by ELISA. Differences in disease resistance to each fungus were observed between resistant and susceptible pools in most populations and environments indicating that selection after inoculation with a single species might be effective to develop broad-based resistance to Fusarium. Resistant pools exhibited, after inoculation with F. verticillioides, low grain fumonisin concentrations in most populations and years. Positive genotypic correlations between disease severity and fumonisin concentration (0.89 \ r g \ 0.98, depending on fungal species and year) indicate that selection for disease severity accounted for most of the variability for field fumonisin accumulation. Selection seemed to be also effective to reduce grain deoxynivalenol and zearalenone concentrations after inoculation with F. graminearum. Ratios between grain deoxynivalenol concentration and disease severity were lower in L7310 9 L7266 than those observed in the other populations suggesting that mechanisms affecting mycotoxin accumulation might exist in this population and additional responses should be feasible if including deoxynivalenol concentration as another selection parameter.

Quantitative trait loci for Fusarium and Gibberella ear rot resistance in Argentinian maize germplasm

“…To select the parents of the mapping population, single rows of 650 F 7 -to-F 9 inbreds representing a wide range of variability of the Argentinian temperate maize germplasm, were evaluated in Pergamino 2004/2005, for resistance to ear rot after inoculation of P319, a highly aggressive isolate belonging to Section Liseola Presello et al 2011). Twenty of the most resistant and some susceptible inbreds were selected.…”

“…These results indicate that disease severity accounts for most of grain mycotoxin concentration and selection for disease resistance would produce indirect responses for grain mycotoxin accumulation. Specific host mechanisms preventing mycotoxin accumulation regardless of the amount of disease also seem to exist (Presello et al 2011) and further genetic progress might be achieved by understanding and using such mechanisms.…”

Genetic Factors Involved in Fumonisin Accumulation in Maize Kernels and Their Implications in Maize Agronomic Management and Breeding

“…However, direct selection for reduction of mycotoxin contamination is expensive and time consuming, so indirect, cheaper and less time consuming selection criteria are necessary [ 97 ]. In this context, Fusarium ear rot has emerged as a suitable trait for performing indirect selection because high genotypic correlations between Fusarium ear rot and fumonisin contents have been reported [ 92 , 95 , 96 , 97 , 98 ].We also include those works focused on exploring genetic variability for Fusarium ear rot and/or to study maize genetics involved in resistance to Fusarium ear rot.…”

“…In parallel, the private industry began to release inbreds and hybrids with above average resistance to Fusarium ear rot according to the seed patents from Pioneer Hi-bred Int Inc approved since 1997 [ 141 , 142 , 143 , 144 , 145 , 146 , 147 ]. More interestingly, breeding for resistance to one mycotoxigenic species could affect resistance to other ones [ 98 , 130 , 132 ].…”

Effect of Environmental Factors on Fusarium Species and Associated Mycotoxins in Maize Grain Grown in Poland

“…The use of genetic resistance is one of the most effective practices for disease control, and pedigree selection is an effective method to obtain genetic gain for ear rot resistance [ 30 – 33 ]. Another important part of effective crop protection strategy against ear rot is monitoring the Fusarium species associated with maize as well as with the specific environment [ 34 ].…”