Transcriptional Regulation of Sorghum Defense Determinants against a Phloem-Feeding Aphid

Abstract

When attacked by a phloem-feeding greenbug aphid (Schizaphis graminum), sorghum (Sorghum bicolor) activates jasmonic acid (JA)- and salicylic acid (SA)-regulated genes, as well as genes outside known wounding and SA signaling pathways. A collection of 672 cDNAs was obtained by differential subtraction with cDNAs prepared from sorghum seedlings infested by greenbug aphids and those from uninfested seedlings. Subsequent expression profiling using DNA microarray and northern-blot analyses identified 82 transcript types from this collection responsive to greenbug feeding, methyl jasmonate (MeJA), or SA application. DNA sequencing analyses indicated that these encoded proteins functioning in direct defense, defense signaling, oxidative burst, secondary metabolism, abiotic stress, cell maintenance, and photosynthesis, as well as proteins of unknown function. In response to insect feeding, sorghum increased transcript abundance of numerous defense genes, with some SA-dependent pathogenesis-related genes responding to greenbug more strongly than to SA. In contrast, only weak induction of MeJA-regulated defense genes was observed after greenbug treatment. However, infestation tests confirmed that JA-regulated pathways were effective in plant defense against greenbugs. Activation of certain transcripts exclusively by greenbug infestation was observed, and may represent unique signal transduction events independent of JA- and SA-regulated pathways. Results indicate that plants coordinately regulate defense gene expression when attacked by phloem-feeding aphids, but also suggest that aphids are able to avoid triggering activation of some otherwise potentially effective plant defensive machinery, possibly through their particular mode of feeding.

Dynamic maize responses to aphid feeding are revealed by a time series of transcriptomic and metabolomic assays

“…been observed in several plant species (Zhu-Salzman et al, 2004;Park et al, 2006;Kerchev et al, 2013;Hillwig et al, 2015). Abscisic acid signaling often has been associated with osmotic stress responses in plants, leading to the hypothesis that removal of phloem content by aphids can cause wilting and thereby mimic osmotic stress.…”

“…In particular, after 48 and 96 h of aphid feeding, the transcriptomic and metabolic patterns in the maize leaves are more similar to those of control plants than at 4 and 8 h of aphid feeding. Similar, time point-specific variation in plant gene expression has been observed in other aphid-plant interactions, for instance in comparisons of significantly altered transcripts after 24, 48, and 96 h of potato aphid (Macrosiphum euphorbiae) feeding on tomato (Solanum lycopersicum; Coppola et al, 2013), 6 and 24 h of green peach aphid (Myzus persicae) and cabbage aphid (Brevicoryne brassicae) feeding on Arabidopsis (Appel et al, 2014), and 6, 12, 24, and 48 h of greenbug aphid (Schizaphis graminum) feeding on sorghum (Sorghum bicolor; Zhu-Salzman et al, 2004). In each experiment, there was limited overlap in the plant gene expression patterns at each Figure 5.…”

Transcriptional responses of tolerant and susceptible soybeans to soybean aphid (Aphis glycines Matsumura) herbivory

“…Microarrays have been routinely used to study plant responses to insect herbivory (Reymond et al 2000;Halitschke et al 2003;Voelckel et al 2004;Park et al 2005a, b;Smith and Boyko 2007;Li et al 2008b;Gutsche et al 2009). Relatively, few of these studies have used plants with divergent responses to aphids (Zhu-Salzman et al 2004;Park et al 2005a, b;Couldridge et al 2007;Kempema et al 2007;Li et al 2008b;De Vos and Jander 2009;Studham and Macintosh 2013). Here we have used NGS to compare and contrast changes in leaf transcriptomes from tolerant and susceptible soybean plants in response to infestation by A. glycines that may help uncover more about the tolerant response found in soybean KS4202.…”

Transcriptional Profiling of Sorghum Induced by Methyl Jasmonate, Salicylic Acid, and Aminocyclopropane Carboxylic Acid Reveals Cooperative Regulation and Novel Gene Responses

“…6). Such antagonisms have been seen as a mechanism evolved to conserve resources by limiting defense responses to genes effective against microbial pathogens versus insects (Zhu-Salzman et al, 2004), or to fine-tune antimicrobial defenses to counter SAR-inducing biotrophic versus JA-inducing necrotrophic pathogens (Thomma et al, 2001). Pathogens may also have evolved the ability to turn SA/JA antagonisms to their own advantage.…”