Transcriptional profile of sweet orange in response to chitosan and salicylic acid

Abstract

BackgroundResistance inducers have been used in annual crops as an alternative for disease control. Wood perennial fruit trees, such as those of the citrus species, are candidates for treatment with resistance inducers, such as salicylic acid (SA) and chitosan (CHI). However, the involved mechanisms in resistance induced by elicitors in citrus are currently few known.ResultsIn the present manuscript, we report information regarding the transcriptional changes observed in sweet orange in response to exogenous applications of SA and CHI using RNA-seq technology. More genes were induced by SA treatment than by CHI treatment. In total, 1,425 differentially expressed genes (DEGs) were identified following treatment with SA, including the important genes WRKY50, PR2, and PR9, which are known to participate in the salicylic acid signaling pathway, and genes involved in ethylene/Jasmonic acid biosynthesis (ACS12, AP2 domain-containing transcription factor, and OPR3). In addition, SA treatment promoted the induction of a subset of genes involved in several metabolic processes, such as redox states and secondary metabolism, which are associated with biotic stress. For CHI treatment, there were 640 DEGs, many of them involved in secondary metabolism. For both SA and CHI treatments, the auxin pathway genes were repressed, but SA treatment promoted induction in the ethylene and jasmonate acid pathway genes, in addition to repressing the abscisic acid pathway genes. Chitosan treatment altered some hormone metabolism pathways. The DEGs were validated by quantitative Real-Time PCR (qRT-PCR), and the results were consistent with the RNA-seq data, with a high correlation between the two analyses.ConclusionsWe expanded the available information regarding induced defense by elicitors in a species of Citrus that is susceptible to various diseases and identified the molecular mechanisms by which this defense might be mediated.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-015-1440-5) contains supplementary material, which is available to authorized users.

Regulation of citrus responses to the combined action of drought and high temperatures depends on the severity of water deprivation

“…S1), paralleling the higher impact of this stress combination on plant physiology, compared to individual stress components. In the present work, SA accumulation pattern was similar, finding the highest hormone content as well as the up‐regulation of ICS (SA‐biosynthetic gene, Dempsey et al ) and PR2 (a SA‐inducible gene, Coqueiro et al ) in plants subjected to combined moderate drought and heat (Fig. ).…”

Chitin and chitin-related compounds in plant–fungal interactions

“…In contrast to chitin, chitosan appears to elicit activity from plant cells via charge–charge interactions with negatively charged phospholipids instead of via a receptor-specific interaction (Kauss et al 1989). The differential expression of key elements under SA and chitosan treatment were investigated by Coqueiro et al (2015) in orange by RNA-seq technology. More genes were induced by SA treatment than by chitosan treatment.…”

“…More genes were induced by SA treatment than by chitosan treatment. Under chitosan treatment, there were 640 differentially expressed genes, many of them involved in secondary metabolism and the treatment also altered some hormone metabolism pathways (Coqueiro et al 2015). It was found that chitosan amendment increased plant phenylalanine ammonia lyase activity, which is the crucial enzyme of phenylpropanoid metabolism, and the subsequent increase in phenolic content, polyphenol oxidase, peroxidase, and chitinase is a general response associated with disease resistance (Anand et al 2009; Mejía-Teniente et al 2013).…”

BrEXLB1, a Brassica rapa Expansin-Like B1 Gene Is Associated with Root Development, Drought Stress Response, and Seed Germination

“…Expansins (EXPs) are cell wall structural proteins which regulate wall expansion during cell growth [1] and stress responses [2] by weakening the hydrogen bond between cell wall polysaccharides. Emerging studies showed that phytohormones interact with the EXPs to coordinate many physiological and cellular processes of plant growth in response to developmental and environmental stimuli [3][4][5]. Phytohormones, including cytokinin, jasmonate, and gibberellin, induce the expression of EXP superfamily [6].…”