Physiological, Nutritional, and Biochemical Bases of Corn Resistance to Foliage-Feeding Fall Armyworm

Abstract

Three corn (Zea mays) germplasm lines [i.e., Ab24E (susceptible control), Mp708 (resistant control), and a locally selected partial inbred line FAW7050 (resistant)] were examined for Spodoptera frugiperda (J.E. Smith; Lepidoptera: Noctuidae) resistance. Nutritional [i.e., total protein content, amino acids, glucose, total nonstructural carbohydrates (TNC), protein to TNC (P/C) ratios] and biochemical (i.e., peroxidase and lipoxygenase 3) properties in the seedlings of these corn lines were examined to categorize resistance mechanisms to S. frugiperda. Physiological changes in photosynthetic rates also were examined in an attempt to explain nutritional and biochemical dynamics among corn germplasm lines and between insect-infested and noninfested corn plants within a germplasm line. Results indicated that S. frugiperda larvae survived better and developed faster in susceptible Ab24E than in resistant FAW7050 or Mp708. The three germplasm lines differed in resistance mechanisms to S. frugiperda, and the observed patterns of resistance were probably collective results of the P/C ratio and defensive proteins. That is, the susceptibility of Ab24E to S. frugiperda was due to a high P/C ratio and a low level of induced defensive compounds in response to insect herbivory, while the resistance of FAW7050 resulted from elevated defensive proteins following insect herbivory, low P/C ratio, and elevated defensive proteins in Mp708 contributed to its resistance to S. frugiperda. The elevated protein amounts in resistant Mp708 and FAW7050 following S. frugiperda injury were likely due to greater conversion of photosynthates to defensive proteins following the greater photosynthetic rates in these entries. Greater photosynthetic capacity in Mp708 and FAW7050 also led to higher amino acid and glucose contents in these two lines. Neither amino acid nor lipoxygenase 3 played a critical role in corn resistance to S. frugiperda. However, high inducibility of peroxidase may be an indicator of S. frugiperda susceptibility as observed elsewhere.

Biology and nutrition of Spodoptera frugiperda (Lepidoptera: Noctuidae) fed on different food sources

“…Total nitrogen varied from 2.27 to 3.47 (percentage of dry weight). Chen et al (2009), evaluating leaves of different maize germplasm lines, reported leaf chlorophyll (µmol m −2 ) from 522.56 to 610.37; total protein (mg g −1 of fresh weight of leaf tissue) from 5.74 to 11.12; amino acids (µmol g −1 of fresh weight of leaf tissue) from 6.43 to 11.0; glucose (µmol g −1 of fresh weight of leaf tissue) from 6.39 to 17.26; total nonstructural carbohydrate as the sum of glucose and starch (equivalents of glucose) (µmol g −1 of fresh weight of leaf tissue) from 24.25 to 27.94 and the relationship of protein/carbohydrate (w/w) from 1.27 to 2.69. However, nutrient availability to insects is frequently variable.…”

Biochemical factors associated with cassava resistance to whitefly infestation

“…The results confirm those of Taggar et al (2012) and Taggar et al (2014) who found that B. tabaci feeding in black gram cultivars, increased peroxidase activity and tannin content in the genotypes. Production of phenoxy and other oxidative radicals by the PODs, acting together with phenols such as tannins, have been reported to directly deter the feeding by insects and/or produce toxins that reduce the plant digestibility, which leads to nutrient deficiency in insects with drastic effects on their growth and development (Chen et al, 2009).…”

Mechanisms of plant defense against insect herbivores

“…65 Immuno-labeling GNA assay has shown its presence in the fat bodies, ovarioles, and hemolymph, indicating the ability of GNA to cross the midgut that a wide spectrum of PRPs is involved in plant defense against herbivores. 56,57 Due to diverse feeding habits of arthropods, multiple signaling pathways including jasmonic acid (JA), SA and/or ethylene (ET) regulate arthropod-inducible proteins. 8 Plant lectins.…”

“…Induction of antioxidative enzymes in plants following herbivory has received considerable attention in recent years. [4][5][6][55][56][57][58][59] epithelial barrier and pass into the insect's circulatory system leading to systemic toxic effect. 65 Partial resistance to homopteran insect pests has been reported in transgenic plants expressing snowdrop lectin in tobacco, 66 rice, 67 and wheat.…”