The Role of Pericarp Cell Wall Components in Maize Weevil Resistance

Abstract

The maize weevil (MW), Sitophilus zeamais (Motsch.), is a storage pest that causes serious losses in maize (Zea mays L.) in developing countries. This study was conducted to investigate the role of pericarp cell wall components as factors that contribute to MW resistance in nine genotypes of tropical maize. Six susceptibility parameters to MW were measured and related to cell wall components such as simple phenolic acids, diferulic acids (DiFAs), hydroxyproline‐rich glycoproteins (HRGPs), and nutritional and physical traits. Weevil susceptibility was negatively correlated (P < 0.001) with total DiFAs (r = −0.77), HRGPs (r = −0.82), grain hardness (r = −0.87), pericarp/whole kernel (P/K) ratio (r = −0.68), and pericarp thickness (r = −0.86). A detailed analysis of phenolics indicated the presence of trans‐ferulic acid (FA), p‐coumaric acid (CA), and four isomers of DiFA. The most prominent were 5,5′‐DiFA, 8‐O‐4‐DiFA, and 8,5′‐DiFA benzofuran form (DiFAb). On the basis of regression models, 5,5′‐DiFA, 8‐O‐4‐DiFA, trans‐FA, and p‐CA were the most important phenolic components of resistance. Grain hardness was correlated (P < 0.001) with cell wall bound HRGPs (r = 0.61) and DiFAs (r = 0.75). Cell wall cross‐linking components could contribute to MW resistance by fortification of the pericarp cell wall as well as increase grain hardness. This structurally based mechanism should be considered in the development of hybrids and varieties where storage pests are prevalent.

Comparative resistance of improved maize genotypes and landraces to maize weevil

“…Although genotypes were not statistically different for protein content (Table 1), a closer look at the best 5 and worst 5 genotypes revealed a tendency for genotypes with higher protein content to be resistant (based on the classification of the genotypes done at CIMMYT, Zimbabwe). This is consistent with what other investigators have found (Derera et al, 2001;Dhliwayo and Pixley, 2003;Garcia-Lara et al, 2004). The fact that protein content did not have a definite relationship with physical resistance parameters in this study may indicate that there are other resistance factors in maize studied.…”

“…Progeny emergence tended to be higher in susceptible genotypes than in resistant ones (Garcia-Lara et al, 2004). In this study, the susceptible check had the highest number of the total F 1 emergence, numbering up to 87 weevils, against the experimental mean of 13 weevil emergencies.…”

Evaluation of CIMMYT drought tolerant maize germplasm for resistance to weevil (Sitophilus zeamais Motschulky) damage

“…Resistant maize genotypes are usually characterized with no/very low F 1 weevil progeny emergence after a long period of time (64 days) while susceptible maize varieties are characterized with greater numbers of F 1 WPE in a very short time period (32 days) under favorable humidity (70±5) and temperature (28±2) conditions (Dhliwayo and Pixley, 2004). Basing on the literature gathered from García-Lara et al (2004) it can be postured from this study that, hybrids (CZH131022, CZH131003 and CZH132064) that exhibited low F 1 weevil progeny emergence might contain phenolic compounds that might have discouraged faster rate of weevil oviposition and development. There is also a possibility that these hybrids are lacking nutrients that are required to support weevil oviposition and development.…”

“…Mechanisms and level of Mandizvidza et al 4151 resistance to weevil damage varies among maize genotypes and this is determined by the composition of particular kernels of a maize variety. Some varieties (weevil resistant) contain different compounds that discourage their successful utilization as hosts by insect species while others (susceptible) contain compounds favorable for weevil oviposition (García-Lara et al, 2004). These compounds vary greatly among maize varieties and can be passed on from one generation to another.…”

DAÑOS CAUSADOS POR EL BARRENADOR MAYOR DE LOS GRANOS Prostephanus truncatus (Horn) (COLEOPTERA: BOSTRICHIDAE) EN MAÍZ Y RAMAS DE PLANTAS SILVESTRES

“…Sin embargo, muchos de estos métodos demandan tiempo, costo y personal especializado. La implementación de nuevos métodos permitiría una evaluación más eficiente y efectiva de la resistencia de las variedades a las principales plagas de postcosecha (Bergvinson & García-Lara, 2004).…”