Proteomic and Phytohormone Analysis of the Response of Maize (Zea mays L.) Seedlings to Sugarcane Mosaic Virus

Abstract

BackgroundSugarcane mosaic virus (SCMV) is an important virus pathogen in crop production, causing serious losses in grain and forage yields in susceptible cultivars. Control strategies have been developed, but only marginal successes have been achieved. For the efficient control of this virus, a better understanding of its interactions and associated resistance mechanisms at the molecular level is required.Methodology/Principal FindingsThe responses of resistant and susceptible genotypes of maize to SCMV and the molecular basis of the resistance were studied using a proteomic approach based on two-dimensional polyacrylamide gel electrophoresis (2-DE) and matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS/MS) analysis. Ninety-six protein spots showed statistically significant differences in intensity after SCMV inoculation. The classification of differentially expressed proteins showed that SCMV-responsive proteins were mainly involved in energy and metabolism, stress and defense responses, and photosynthesis. Most of the proteins identified were located in chloroplasts, chloroplast membranes, and the cytoplasm. Analysis of changes in phytohormone levels after virus inoculation suggested that salicylic acid, abscisic acid, jasmonic acid, and azelaic acid may played important roles in the maize response to SCMV infection.Conclusions/SignificanceAmong these identified proteins, 19 have not been identified previously as virus-responsive proteins, and seven were new and did not have assigned functions. These proteins may be candidate proteins for future investigation, and they may present new biological functions and play important roles in plant-virus interactions. The behavioural patterns of the identified proteins suggest the existence of defense mechanisms operating during the early stages of infection that differed in two genotypes. In addition, there are overlapping and specific phytohormone responses to SCMV infection between resistant and susceptible maize genotypes. This study may provide important insights into the molecular events during plant responses to virus infection.

Maize phenylalanine ammonia‐lyases contribute to resistance to Sugarcane mosaic virus infection, most likely through positive regulation of salicylic acid accumulation

“…However, cauliflower mosaic virus (CaMV) (Love et al ., ), cucumber mosaic virus (Zhou et al ., ), potato virus Y (Krečič‐Stres et al ., ) and turnip mosaic virus (Whitham et al ., ) induce increased SA accumulation and SA‐responsive gene expression as they spread through their susceptible hosts. SCMV infection was previously reported to cause SA accumulation in maize inbred lines (Wu et al ., ), but the role of SA in SCMV–maize interactions was not clarified. In this study, we first determined that SA levels in the SCMV‐infected plants increased by 10.1‐ and 3.8‐fold at 7 and 14 days post‐inoculation (dpi), respectively, compared with levels in mock‐inoculated plants (Fig.…”

“…SCMV infection induced endogenous SA accumulation in maize plants and increased expression of the SA‐regulated genes ZmPR1 and ZmPR5 . Increases in SA accumulation have been observed in several compatible plant–virus interactions (Krečič‐Stres et al ., ; Love et al ., ; Whitham et al ., ; Wu et al ., ; Zhou et al ., ). Results of a previous study suggested an increase in SA in maize infected by SCMV (Wu et al ., ) but the role of SA in SCMV infection remains unclear.…”

“…Increases in SA accumulation have been observed in several compatible plant–virus interactions (Krečič‐Stres et al ., ; Love et al ., ; Whitham et al ., ; Wu et al ., ; Zhou et al ., ). Results of a previous study suggested an increase in SA in maize infected by SCMV (Wu et al ., ) but the role of SA in SCMV infection remains unclear. Interestingly, SCMV‐induced SA accumulation was greater at 7 dpi than at 14 dpi, suggesting that accumulation of this metabolite declines once the most active period of viral spread has concluded.…”

“…The phenylpropanoid pathway is also involved in the biosynthesis of many plant defensive compounds, including flavonoids, lignin, condensed tannins, hydroxycinnamic acid, coumarins and stilbenes (An and Mou, ; Yu and Jez, ). Though SCMV infection causes SA accumulation in susceptible and resistant inbred lines of maize (Wu et al ., ), the biosynthetic pathway and its role in defence against virus infection in maize remain unclear.…”

Maize Biochemical Defences against a Rootworm Were Mediated by Domestication, Spread, and Breeding

“…AZA acts as a signal associated with SAR (systemic acquired resistance), particularly an inducer of SA accumulation upon pathogen attack [92,93]. For example, one study found that AZA plays an important role in maize response to infection by sugarcane mosaic virus [94]. However, another study proposed that AZA functions as a signal in multiple systemic immunity programs, not exclusively as an inducer of SAR, and may cause morphological changes in roots by inhibiting primary root growth and increasing lateral root density [60].…”