Plant Science

‘Candidatus Liberibacter asiaticus,’ an uncultured α-proteobacterium, is associated with citrus huanglongbing (HLB, yellow shoot disease), a destructive disease threatening citrus production worldwide. Here, we reported the draft genome sequence of ‘Ca. L. asiaticus’ strain Myan16 from an HLB-affected lime tree in Myitkyina, Kachin State, Myanmar. The strain Myan16 genome is 1,229,102 bp with an average G+C content of 36.4%, along with a circular prophage: P-Myan16-2 (36,303 bp, type 2). This is the first genome sequence of a ‘Ca. L. asiaticus’ strain from Myanmar, which will enrich the current ‘Ca. L. asiaticus’ genome sequence database and facilitate HLB epidemiology research in Asia and world.

‘Candidatus Liberibacter asiaticus’ is an insect-transmitted, phloem-restricted α-proteobacterium associated with huanglongbing. Here, we provide the whole genome sequence of ‘Ca. L. asiaticus’ strain ReuSP1 from its insect vector Diaphorina citri (Hemiptera: Liviidae) collected in La Réunion. The genome is composed of 1,230,064 bp and has a 36.5% G+C content. This study reports the first ‘Ca. L. asiaticus’ genome sequence from La Réunion, which will add to ‘Ca. L. asiaticus’ genome resources and help elucidate our understanding of the introduction pathway into La Réunion.

Understanding temporal biological phenomena is a challenging task that can be approached using network analysis. Here, we explored whether network reconstruction can be used to better understand the temporal dynamics of bois noir, which is associated with ‘Candidatus Phytoplasma solani’, and is one of the most widespread phytoplasma diseases of grapevine in Europe. We proposed a methodology that explores the temporal network dynamics at the community level, i.e., densely connected subnetworks. The methodology offers both insights into the functional dynamics via enrichment analysis at the community level, and analyses of the community dissipation, as a measure that accounts for community degradation. We validated this methodology with cases on experimental temporal expression data of uninfected grapevines and grapevines infected with ‘Ca. P. solani’. These data confirm some known gene communities involved in this infection. They also reveal several new gene communities and their potential regulatory networks that have not been linked to ‘Ca. P. solani’ to date. To confirm the capabilities of the proposed method, selected predictions were empirically evaluated.

The present study examined the effects of Candidatus Phytoplasma solani infection on antioxidative metabolism in leaves and roots of carrot (Daucus carota L.). Disease symptoms appeared at the end of June in the form of the chlorosis on some of the leaves, which became intensely red one week later, while the previously healthy leaves from the same branch becme chlorotic. A few days later, all leaves from the infected leaf branch were intensely red. Infected plants also had slower growth compared to the healthy ones with fewer leaf branches developed. The roots of infected plants were less developed, seared, or gummy with or without brown-colored root hair. The presence of the pathogen was detected by sequencing the 16S rRNA. National Center for Biotechnology Information (NCBI) BLAST analyses of the obtained sequence revealed 100% identity of tested strain with deposited Ca. Phytoplasma solani strains from various countries and hosts, all belonging to the “stolbur” group (16SrXII-A). Identity of 99.74% was found when the tested Serbian strain (MF503627) was compared with the reference stolbur strain STOL11 (AF248959). The oxidative damage of membranes in carrot cells was accompanied by a decrease in the content of photosynthetic pigments. Furthermore, for the determination of specific scavenging properties of the extracts, in vitro antioxidant assay was performed. In phytoplasma-infected carrot leaves, there was a greater reduction in the level of glutathione content (GSH); however; flavonoids and anthocyanidins seem to be responsible for the accompanied increased antioxidative capacity against hydroxyl radical and hydrogen peroxide.