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Advances in conventional breeding for insect resistance in tropical maize

By: Bergvinson, D.J | Centro Internacional de Mejoramiento de Maiz y Trigo (CIMMYT), Mexico, DF (Mexico).
Contributor(s): Panwar, V.P.S [coaut.] | Sekhar, J.C [coaut.] | Singh, N.N [coaut.] | Srinivasan, G.|Zaidi, P.H.|Prasanna, B.M.|Gonzalez, F.|Lesnick, K [eds.] | Vasal, S.K [coaut.].
Material type: materialTypeLabelBookAnalytics: Show analyticsPublisher: Mexico, DF (Mexico) CIMMYT : 2004Description: p. 325-338.ISBN: 970-648-116-8.Subject(s): Chilo partellus | insect resistance | Maize | Pest resistance | Prostephanus truncatus | Sesamia inferens | Sitophilus zeamais | Storage | Tropical crops | CIMMYT | Plant breeding AGROVOCSummary: Insects attack maize throughout the cropping cycle and during storage, resulting in as little as 10% up to complete crop loss. To address this problem, the International Maize and Wheat Improvement Center (CIMMYT) has developed methodologies to facilitate breeding for host plant resistance (HPR) to the major insect pests attacking maize. The major field pests targeted for Asia include the spotted stem borer (Chilo partellus (Swinhoe)) and the pink stem borer (Sesamia inferens Walker). In collaboration with entomologists and breeders in India, Thailand and the Philippines, 15 tropical lines have been identified with a moderate level of resistance to the above stem borers while having good regional adaptation and agronomic performance. There was no correlation between downy mildew resistance and stem borer resistance. Tropical maize germplasm developed by CIMMYT programs in Asia and Mexico have been screened for their susceptibility to storage pests, using the maize weevil (MW), Sitophilus zeamais (Motsch.) and the larger grain borer, Prostephanus truncatus Horn. Several lines and hybrids have been identified with moderate levels of resistance to the MW, with several lines being identified from the Asian program. In addition to characterizing advanced lines and hybrids, CIMMYT has also developed source populations for storage pest resistance using intra- population improvement. This paper will also present CIMMYT's breeding strategy for developing HPR in maize and our current understanding of the biochemical basis for both stem borer and storage pest resistance. In Asia, maize is an important food crop for the poorest fraction of society who does not have the resources to apply pesticides during crop development nor in grain storage to prevent losses to insect pests. There is a genuine need by resource poor farmers for maize germplasm with moderate levels of resistance to insect pests that reduce both yield potential and grain quality. Host plant resistance has been demonstrated in both field and storage pests for maize and is considered the cornerstone of an integrated pest management program (Ortega et al., 1980). Over the past two decades, CIMMYT and its research partners around the world have worked towards developing screening techniques and breeding protocols that have enabled the development and release of insect resistant maize germplasm (Mihm, 1984). Stem borer damage to maize posses a significant constraint on regional maize production by damaging the vascular tissue of the plant and providing a portal of entry for stalk and ear rots. Yield losses due to field pests is variable but ranges from 10% in China (Darong et al., 1998) to crop failure under outbreak conditions. The major stem borer species in Asia for which screening protocols have been developed and used in a breeding program include the Asian corn borer, Ostrinia furnicalis, the spotted stem-borer, Chilo partellus, and the pink stem borer, Sesamia inferens (Mihm, 1984). Following the development of mass-rearing procedures and a mechanical dispenser called the "bazooka" in the mid-1970's, HPR research for maize made significant progress through the combined efforts of entomologists and breeders. With the development of lines with elevated levels of stem borer resistance, research on the genetic and biochemical basis of resistance was possible. Using molecular markers, quantitative trait loci for stem borer resistance were localized and linked markers that were used to move resistant alleles from IR lines into elite lines (Willcox et al., 2002). The biochemical basis of stem borer resistance in tropical maize has also been identified to include increased thickness and toughness of the epidermal cell wall and associated increases in the level of fiber content and cell wall cross-linking agents such as DiFA that fortify the cell wall and impede feeding by neonate larvae (Bergvinson et al., 1997). This more complete understanding of HPR has enabled IR lines to be developed with increased agronomic performance. Another group of destructive insects are those found in maize stores. Losses in tropical and subtropical agroecologies are the most severe, with losses in excess of 15% occurring during on-farm storage by subsistence farmers. Using grain weight loss equations generated from a range of storage environments in Mexico, a geographical information system (GIS) can be used to estimate losses in Asia. The example in Fig. 1 shows grain weight losses for the month of July, with losses ranging from 1.5 to 4% weight loss or 15-30% kernel damage. The use of insect resistant varieties has been proposed in the past (Dobie, 1977) as part of an integrated pest management strategy to reduce losses and improve grain quality. Several ize varieties, including local landraces, have been characterized as sources of resistance to MW (Dobie, 1977; Arnason et al., 1994) with some sources of resistance being incorporated into elite maize lines (Bergvinson, 2001). In maize, the mechanisms of kernel resistance to MW have been investigated in relation to biochemical and physical characteristics (Arnason et al.,1994). The pericarp of MW resistant maize has high concentrations of simple phenolics, namely hydroxycinnamic acids (Arnason et al., 1997). Several reports have established that these phenolic acids are ester-linked to cell wall polysaccharides, as well as phenolic dimers, such as DiFA (Ishii, 1997). Recent evidence has demonstrated that MW resistant genotypes have higher concentrations of total DiFAs (Arnason et al., 1994, 1997). Cross- linking of polysaccharides by DiFAs is considered particularly important in fortification of the pericarp cell wall. This pap reports on insect resistant germplasm developed by CIMMYT and its research partners. Based on our current understanding regarding the biochemical basis for resistance, we will also discuss which resistance mechanisms should be utilized to ensure the incorporation of stable resistance and high yield potential into local germplasm enhancement programs.Collection: CIMMYT Staff Publications Collection
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Conference proceedings CIMMYT Knowledge Center: John Woolston Library

Lic. Jose Juan Caballero Flores

 

CIMMYT Staff Publications Collection CIS-4297 (Browse shelf) 1 Available 630610
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Insects attack maize throughout the cropping cycle and during storage, resulting in as little as 10% up to complete crop loss. To address this problem, the International Maize and Wheat Improvement Center (CIMMYT) has developed methodologies to facilitate breeding for host plant resistance (HPR) to the major insect pests attacking maize. The major field pests targeted for Asia include the spotted stem borer (Chilo partellus (Swinhoe)) and the pink stem borer (Sesamia inferens Walker). In collaboration with entomologists and breeders in India, Thailand and the Philippines, 15 tropical lines have been identified with a moderate level of resistance to the above stem borers while having good regional adaptation and agronomic performance. There was no correlation between downy mildew resistance and stem borer resistance. Tropical maize germplasm developed by CIMMYT programs in Asia and Mexico have been screened for their susceptibility to storage pests, using the maize weevil (MW), Sitophilus zeamais (Motsch.) and the larger grain borer, Prostephanus truncatus Horn. Several lines and hybrids have been identified with moderate levels of resistance to the MW, with several lines being identified from the Asian program. In addition to characterizing advanced lines and hybrids, CIMMYT has also developed source populations for storage pest resistance using intra- population improvement. This paper will also present CIMMYT's breeding strategy for developing HPR in maize and our current understanding of the biochemical basis for both stem borer and storage pest resistance. In Asia, maize is an important food crop for the poorest fraction of society who does not have the resources to apply pesticides during crop development nor in grain storage to prevent losses to insect pests. There is a genuine need by resource poor farmers for maize germplasm with moderate levels of resistance to insect pests that reduce both yield potential and grain quality. Host plant resistance has been demonstrated in both field and storage pests for maize and is considered the cornerstone of an integrated pest management program (Ortega et al., 1980). Over the past two decades, CIMMYT and its research partners around the world have worked towards developing screening techniques and breeding protocols that have enabled the development and release of insect resistant maize germplasm (Mihm, 1984). Stem borer damage to maize posses a significant constraint on regional maize production by damaging the vascular tissue of the plant and providing a portal of entry for stalk and ear rots. Yield losses due to field pests is variable but ranges from 10% in China (Darong et al., 1998) to crop failure under outbreak conditions. The major stem borer species in Asia for which screening protocols have been developed and used in a breeding program include the Asian corn borer, Ostrinia furnicalis, the spotted stem-borer, Chilo partellus, and the pink stem borer, Sesamia inferens (Mihm, 1984). Following the development of mass-rearing procedures and a mechanical dispenser called the "bazooka" in the mid-1970's, HPR research for maize made significant progress through the combined efforts of entomologists and breeders. With the development of lines with elevated levels of stem borer resistance, research on the genetic and biochemical basis of resistance was possible. Using molecular markers, quantitative trait loci for stem borer resistance were localized and linked markers that were used to move resistant alleles from IR lines into elite lines (Willcox et al., 2002). The biochemical basis of stem borer resistance in tropical maize has also been identified to include increased thickness and toughness of the epidermal cell wall and associated increases in the level of fiber content and cell wall cross-linking agents such as DiFA that fortify the cell wall and impede feeding by neonate larvae (Bergvinson et al., 1997). This more complete understanding of HPR has enabled IR lines to be developed with increased agronomic performance. Another group of destructive insects are those found in maize stores. Losses in tropical and subtropical agroecologies are the most severe, with losses in excess of 15% occurring during on-farm storage by subsistence farmers. Using grain weight loss equations generated from a range of storage environments in Mexico, a geographical information system (GIS) can be used to estimate losses in Asia. The example in Fig. 1 shows grain weight losses for the month of July, with losses ranging from 1.5 to 4% weight loss or 15-30% kernel damage. The use of insect resistant varieties has been proposed in the past (Dobie, 1977) as part of an integrated pest management strategy to reduce losses and improve grain quality. Several ize varieties, including local landraces, have been characterized as sources of resistance to MW (Dobie, 1977; Arnason et al., 1994) with some sources of resistance being incorporated into elite maize lines (Bergvinson, 2001). In maize, the mechanisms of kernel resistance to MW have been investigated in relation to biochemical and physical characteristics (Arnason et al.,1994). The pericarp of MW resistant maize has high concentrations of simple phenolics, namely hydroxycinnamic acids (Arnason et al., 1997). Several reports have established that these phenolic acids are ester-linked to cell wall polysaccharides, as well as phenolic dimers, such as DiFA (Ishii, 1997). Recent evidence has demonstrated that MW resistant genotypes have higher concentrations of total DiFAs (Arnason et al., 1994, 1997). Cross- linking of polysaccharides by DiFAs is considered particularly important in fortification of the pericarp cell wall. This pap reports on insect resistant germplasm developed by CIMMYT and its research partners. Based on our current understanding regarding the biochemical basis for resistance, we will also discuss which resistance mechanisms should be utilized to ensure the incorporation of stable resistance and high yield potential into local germplasm enhancement programs.

English

0501|AGRIS 0501|AL-Maize Program

Juan Carlos Mendieta

CIMMYT Staff Publications Collection

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Si tiene cualquier pregunta, contáctenos a CIMMYT-Knowledge-Center@cgiar.org