Transcriptional analysis of Rhazya stricta in response to jasmonic acid

BACKGROUND: Jasmonic acid (JA) is a signal transducer molecule that plays an important role in plant development and stress response; it can also efficiently stimulate secondary metabolism in plant cells. RESULTS: RNA-Seq technology was applied to identify differentially expressed genes and study the time course of gene expression in Rhazya stricta in response to JA. Of more than 288 million total reads, approximately 27% were mapped to genes in the reference genome. Genes involved during the secondary metabolite pathways were up- or downregulated when treated with JA in R. stricta. Functional annotation and pathway analysis of all up- and downregulated genes identified many biological processes and molecular functions. Jasmonic acid biosynthetic, cell wall organization, and chlorophyll metabolic processes were upregulated at days 2, 6, and 12, respectively. Similarly, the molecular functions of calcium-transporting ATPase activity, ADP binding, and protein kinase activity were also upregulated at days 2, 6, and 12, respectively. Time-dependent transcriptional gene expression analysis showed that JA can induce signaling in the phenylpropanoid and aromatic acid pathways. These pathways are responsible for the production of secondary metabolites, which are essential for the development and environmental defense mechanism of R. stricta during stress conditions. CONCLUSIONS: Our results suggested that genes involved in flavonoid biosynthesis and aromatic acid synthesis pathways were upregulated during JA stress. However, monoterpenoid indole alkaloid (MIA) was unaffected by JA treatment. Hence, we can postulate that JA plays an important role in R. stricta during plant development and environmental stress conditions.

New stereoisomeric derivatives of jasmonic acid generated by biotransformation with the fungus Gibberella fujikuroi affect the viability of human cancer cells

Background: Several studies have shown that (-)-Jasmonic acid, (+)-7-iso-Jasmonic acid and its methyl ester, methyl jasmonate, have anti-cancer activity in vitro and in vivo, exhibiting selective cytotoxicity towards cancer cells. The degree of activity of these molecules is strongly related to their stereochemistry. The biotransformation of known compounds, natural or synthesized, related to interesting biological activities, generates new molecules displaying new improved properties compared with the original ones, increasing its value and providing new more effective products. Therefore, based on the above rationales and observations, in this work a biotransformation protocol to modify the chemical structure of the plant hormone jasmonic acid by using the fungus Gibberella fujikuroi was established. Results: The three jasmonic acid derivatives obtained, 3(S)-Hydroxy-2(R)-(2Z-pentenyl)-cyclopentane-1(R)-acetic acid (1), 3(R)-Hydroxy-2(R)-(2Z-pentenyl)-cyclopentane-1(R)-acetic acid (2), 3-Hydroxy-2(S)-(2Z-pentenyl)-cyclopentane-1(S)-acetic acid (3), were tested for cell-growth inhibition activity towards the human cancer epithelial cell line, the oral squamous carcinoma cells (KB). The results obtained show that jasmonic acid derivatives (1-3) are active on human cancer cells examined in different concentration ranges, with IC50 value less than of 25 uM. The compound 3, with the same molecular structure of compounds 1 and 2, but with different stereochemistry, was more active confirming that the activity of jasmonate compounds is related to their stereochemistry and to substituents in the cyclopentane ring. In this study, we also tested the potential proapoptotic activity of compound 3, and our data suggest that it, as other jasmonate compounds, is able to trigger apoptotic death in cancer cells. This event may be correlated at an elevation of reactive oxygen species (ROS). Administration of N-acetylcysteine (NAC) prevented compound 3 cytotoxicity...

Effects of elicitor and copper sulfate on grindelic acid production in submerged cultures of Grindelia pulchella

Grindelia pulchella callus and cell suspension cultures were established from seedling leaves. When several phytoregulator supplementations were assayed in solid Murashige and Skoog medium containing 3 percent (w/v) of sucrose (MS medium), combinations of indole-3-butyric acid (IBA) and N6-benzylaminopurine (BA) resulted the most appropriate conditions to generate fast growing friable calli with detectable levels of grindelic acid. Moreover, the same basal media supplemented with 20.0 µM IBA/4.4 µM BA was found to be optimal for cell growth in submerged cultures (µmax = 0.26 days-1) while the addition of 20.0 µM IBA/18.0 µM BA resulted in a relative higher metabolite production (4.55 mg/gDW) when the inocula was 5 percent (v/v). Furthermore, three different stress factors and combinations of them were used to elicit cell suspensions. These experiments demonstrated that the combination of CuSO4 and dimethylsulfoxide (DMSO) increase the grindelic acid production to 2.63 mg/gDW in the elicited essay versus 0.756 mg/gDW in the control, at expense of cell growth. In contrast, the addition of jasmonic acid (JA) alone and combined with DMSO neither affected cell growth nor grindelic acid accumulation.

Culture filtrate of Lasiodiplodia theobromae restricts the development of natural resistance in Brassica nigra plants.

Culture filtrate of Lasiodiplodia theobromae increased respiration rate, phenylalanine ammonia lyase activity, and levels of hydrogen peroxide, lipid peroxides and salicylic acid in B. nigra plants. Salicylic acid (SA) level increased for 1 hr of interaction and reduced later. Development of systemic acquired resistance (SAR) was found restricted in plants infected with L. theobromae due to deficiency of SA, which is a major signal for development of SAR. Exogenously supplied SA did develop resistance and plant death was delayed. It was hypothesized that deficiency of SA could be due to jasmonic acid produced by fungus that inhibits SA biosynthesis.

Stimulation of jasmonic acid production in Zea mays L. infected by the maize rough dwarf virus-Río Cuarto: reversion of symptoms by salicylic acid

In the present paper we study the possible biological relevance of endogenous jasmonic acid (JA) and exogenous salicylic acid (SA) in a plant-microbial system maize-virus. The virus disease "Mal de Río Cuarto" is caused by the maize rough dwarf virus-Río Cuarto. The characteristic symptoms are the appearance of galls or enations in leaves, shortening of the stem internodes, poor radical system and general stunting. Changes in JA and protein pattern in maize control and infected plants of a virus-tolerant cultivar were investigated. Healthy and infected-leaf discs were collected for JA measurement at different post-infection times (20, 40, 60 and 68 days). JA was also measured in roots on day 60 after infection. For SDS-PAGE protein analysis, leaf discs were also harvested on day 60 after infection. Infected leaves showed higher levels of JA than healthy leaves, and the rise in endogenous JA coincided with the enation formation. The soluble protein amount did not show differences between infected and healthy leaves; moreover, no difference in the expression of soluble protein was revealed by SDS-PAGE. Our results show that the octadecanoid pathway was stimulated in leaves and roots of the tolerant maize cultivar when infected by this virus. This finding, together with fewer plants with the disease symptoms, suggest that higher foliar and roots JA content may be related to disease tolerance. SA exogenous treatment caused the reversion of the dwarfism symptom.