No abstract

SUMOylation, the covalent attachment of the small ubiquitin-like modifier (SUMO) to target proteins, is emerging as a key modulator of eukaryotic immune function. In plants, a SUMO1/2-dependent process has been proposed to control the deployment of host defense responses. The molecular mechanism underpinning this activity remains to be determined, however. Here we show that increasing nitric oxide levels following pathogen recognition promote S-nitrosylation of the Arabidopsis SUMO E2 enzyme, SCE1, at Cys139. The SUMO-conjugating activities of both SCE1 and its human homolog, UBC9, were inhibited following this modification. Accordingly, mutation of Cys139 resulted in increased levels of SUMO1/2 conjugates, disabled immune responses, and enhanced pathogen susceptibility. Our findings imply that S-nitrosylation of SCE1 at Cys139 enables NO bioactivity to drive immune activation by relieving SUMO1/2-mediated suppression. The control of global SUMOylation is thought to occur predominantly at the level of each substrate via complex local machineries. Our findings uncover a parallel and complementary mechanism by suggesting that total SUMO conjugation may also be regulated directly by SNO formation at SCE1 Cys139. This Cys is evolutionary conserved and specifically S-nitrosylated in UBC9, implying that this immune-related regulatory process might be conserved across phylogenetic kingdoms.

Summary• An Arabidopsis PR1::luciferase (LUC) transgenic line was transformed with activation T-DNA tags and the resulting population screened for dominant gain-of-function mutants exhibiting constitutive LUC activity.• LUC imaging identified activated disease resistance 2 (adr2), which exhibited slowly spreading lesions in the absence of pathogen challenge. Molecular, genetic and histochemical analysis was employed to characterize this mutant in detail.• adr2 plants constitutively expressed defence-related and antioxidant genes. Moreover, this line accrued increased quantities of salicylic acid (SA) and exhibited heightened mitogen-activated protein kinase activity. adr2 plants exhibited increased resistance against numerous biotrophic but not necrotrophic pathogens. The adr2 phenotype resulted from the overexpression of a Toll interleukin receptor (TIR) nucleotide binding site (NBS) leucine rich repeat (LRR) gene (At1g56510). Constitutive PR1 expression was completely abolished in adr2 nahG, adr2 npr1 and adr2 eds1 double mutants. Furthermore, heightened resistance against Hyaloperonospora arabidopsis Noco2 was compromised in adr2 nahG and adr2 eds1 double mutants but not in adr2 npr1, adr2 coi1 or adr2 etr1 plants.• These data imply that adr2-mediated resistance operates through an Enhanced Disease Susceptibility (EDS) and SA-dependent defence signalling network which functions independently from COI1 or ETR1.

No abstract

No abstract

No abstract

The genus Jasminum L., of the family Oleaceae, includes many species occurring in the wild, or cultivated worldwide. A preliminary investigation based on inter-simple sequence repeats (ISSR) was performed to assess the genetic diversity among 28 accessions, representing nine species of Jasminum from various regions, representing a range of altitudes in Pakistan. A total of 21 ISSR primers were used, which produced 570 amplified bands of different sizes, with a mean polymorphic band percentage of 98.26%. The maximum resolving power, polymorphism information content, and index values of the ISSR markers recorded for primers 6, 16, and 19 were 0.40, 12.32, and 24.21, respectively. Based on the data of the ISSR markers, the resulting UPGMA dendrogram with the Jaccard coefficient divided the 28 accessions into two main clades. At the species level, the highest values for Shannon’s information index, polymorphism percentage, effective allele number, Nei’s genetic variations, and genetic unbiased diversity were found in Jasminum sambac L. and J. humile L., while the lowest were observed in J. mesnyi Hance and J. nitidum Skan. Based on Nei’s unbiased genetic identity pairwise population matrix, the maximum identity (0.804) was observed between J. elongatum Willd and J. multiflorum (Burm. f.) Andrews, and the lowest (0.566) between J. nitidum Skan. and J. azoricum L. Molecular variance analysis displayed a genetic variation of 79% among the nine populations. The study was aimed to established genetic diversity in Jasminum species using ISSR markers. With the help of this technique, we were able to establish immense intra- and interspecific diversity across the Jasminum species.

No abstract