A plant virus satellite RNA directly accelerates wing formation in its insect vector for spread

Cucumber mosaic virus (CMV) often accompanies a short RNA molecule called a satellite RNA (satRNA). When infected with CMV in the presence of Y-satellite RNA (Y-sat), tobacco leaves develop a green mosaic, then turn yellow. Y-sat has been identified in the fields in Japan. Here, we show that the yellow leaf colour preferentially attracts aphids, and that the aphids fed on yellow plants, which harbour Y-sat-derived small RNAs (sRNAs), turn red and subsequently develop wings. In addition, we found that leaf yellowing did not necessarily reduce photosynthesis, and that viral transmission was not greatly affected despite the low viral titer in the Y-sat-infected plants. Y-sat-infected plants can therefore support a sufficient number of aphids to allow for efficient virus transmission. Our results demonstrate that Y-sat directly alters aphid physiology via Y-sat sRNAs to promote wing formation, an unprecedented survival strategy that enables outward spread via the winged insect vector.

Cucurbit aphid-borne yellows virus (CABYV) infecting melon and bitter gourd in Java, Indonesia

Recently, Cucurbit aphid-borne yellows polerovirus (CABYV) had been reported firstly to infect cucumber in Java. The typical symptoms of CABYV infection are leaf yellowing with green veins and the thickening of older leaves. This study aimed to detect and identify the occurrence of CABYV infection on other cucurbit hosts in Java. A total of 600 Polerovirus-like symptomatic leaves were taken from open-fields cultivated plants in West Java, Central Java, and East Java. The virus incidence was determined serologically, RT-PCR and DNA sequencing confirmed the identity of CABYV. Based on serological test revealed six virus species in single or multiple infections with varying incidence. Among tested plants, the CABYV DNA with size ± 489 bp was successfully amplified from melon in Kediri, Tulungagung, Nganjuk (East Java), Kulonprogo, and bitter gourd in Bogor. The sequencing result confirmed the identity of melon isolates from Nganjuk showed the highest similarity with the CABYV cucumber isolate from Nganjuk and Tulungagung. In contrast, bitter gourd isolates with melon isolates from France and squash isolates from Spain. These are the first reports of CABYV infection on melon and bitter gourd in Java, indicating its rapid host expansion on Cucurbitaceae.

Characterization of Spanish Olive Virome by High Throughput Sequencing Opens New Insights and Uncertainties

The use of high throughput sequencing (HTS) for the analysis of Spanish olive trees showing leaf yellowing discoloration, defoliation, and/or decline has provided new insights into the olive viruses present in Spain and has opened discussions about the pros and cons of these technologies for diagnostic purposes. In this study, we report for the first time in Spanish orchards the presence of olive leaf yellowing-associated virus (OLYaV), for which the second full coding sequence has been determined. This virus has also been detected in a putative vector, the psyllid Euphyllura olivina. In addition, the presence in Spain of Olea europaea geminivirus (OEGV), recently reported in Italy, has been confirmed, and the full-length sequence of two isolates was obtained by HTS and Sanger sequencing. These results, as well as the detection of other viral sequences related to olive latent virus 3 (OLV-3) and olive viral satellite RNA, raises questions on the biological significance of the findings, about the requirement of standardization on the interpretation of HTS results, and the necessity of additional tests to confirm the relevance of the HTS detection of viral sequences.

A Cytokinin Analog Thidiazuron Suppresses Shoot Growth in Potted Rose Plants via the Gibberellic Acid Pathway

Application of thidiazuron (N-phenyl-N′-1,2,3-thiadiazol-5-ylurea, TDZ), a cytokinin analog, to inhibit the leaf yellowing that occurs after pinching potted rose plants, resulted in compact plants with shorter shoots and thicker internodes. Two weeks after treatment with 100 μM of TDZ, new shoots were half as long as those in control plants, and stem diameters were about 40% greater. This effect of TDZ is associated with changes in cell architecture. Although TDZ treatment stimulated ethylene production by the plants, inhibitors of ethylene biosynthesis (2-aminoethoxyvinyl glycine) or action (silver thiosulfate) did not affect the response of plants to TDZ. We found that TDZ treatment significantly suppressed the expression of bioactive gibberellic acid (GA) biosynthesis genes encoding GA3 and GA20 oxidases and slightly increased the expression of GA catabolism genes encoding GA2 oxidase. Application of GA3 and TDZ together resulted in normal elongation growth, although stem diameters were still somewhat thicker. Our results suggest that TDZ regulates shoot elongation and stem enlargement in potted rose plants through the modulation of bioactive GA biosynthesis.

First Report of Fusarium oxysporum Causing Wilt on Coriander in China

Coriander (Coriandrum sativum L), which belongs to the family Apiaceae, is a medicinal and aromatic plant. In China, coriander is widely cultivated in several parts as a vegetable crop. During August 2019 to June 2020, wilting symptoms were observed on coriander (cv. 'Tiegan') in a commercial plantation, with disease incidence of approximately 25 to 40% in Xiajiawang village (118°88′E, 35°46′N) of Linyi city, Shandong province, China. Symptoms included wilting and leaf yellowing, plant stunting, root rot, and vascular discoloration of the stem bases and roots. A total of eight symptomatic plants were uprooted and collected from three fields. To determine the cause of the disease, symptomatic root tissues were excised, surface disinfected with 75% ethanol for 30s, followed by three washes with sterile distilled water, and then placed on potato dextrose agar (PDA) and incubated at 28°C for 6 days. In total, 10 cultures were obtained and purified by single-spore subcultures on PDA for morphological identification. The morphology of multiple colonies was consistent and originally white, later becoming light to dark purple in color with abundant aerial hyphae. Macroconidia were hyaline and falcate, straight to slightly curved, 3-4 septate, 27.86 to 34.23 × 4.07 to 6.13 μm (n = 30), with apical cells curved and basal cells foot-shaped. Microconidia were hyaline, oval or ellipsoid, 0-1 septate, with a flat base, measuring 5.67 to 9.37 × 3.66 to 5.40 μm (n = 30). These morphological characteristics resembled those of Fusarium oxysporum (Leslie and Summerell 2006). Genomic DNA was extracted from fungal mycelium using the Plant Genomic DNA Kit (Tiangen, China). The nuclear ribosomal internal transcribed spacer (ITS), translation elongation factor 1-alpha (TEF-1α) and mitochondrial small subunit (mtSSU) genes were amplified with primer pairs ITS1/ITS4 (White et al. 1990), EF1Ha/EF2Tb (O’ Donnell et al. 1998) and NMS1a/NMS2b (Li et al. 1994). The resulting ITS (550-bp), TEF1-α (681-bp) and mtSSU (692-bp) sequences of isolate QC20091601 were deposited in GenBank (accession nos. MW900439, MW692008 and MW711738, respectively). BLAST analysis demonstrated 100% identities to the ITS, TEF-1α and mtSSU sequences of F. oxysporum (MN856370.1, MN507110.1 and MN386808.1), respectively. According to the morphological and molecular identification, the fungus was identified as F. oxysporum. In the pathogenicity test, healthy coriander plants (cv. 'Tiegan') at the 4-true-leaf stage were inoculated by dipping the roots into a conidial suspension of 1 × 107 conidia/mL for 10 min. Plants dipped in sterile distilled water served as controls. All treated plants were placed in a greenhouse maintained at temperature 30°C and 80% relative humidity. Ten days later, inoculated plants developed typical symptoms of leaf yellowing, wilting and vascular discoloration, which were identical to those observed in the fields, whereas the control plants remained healthy. F.oxysporum was reisolated from the symptomatic roots, and its identity was confirmed by PCR with the primes described above, fulfilling Koch's postulates. To our knowledge, this is the first report of F. oxysporum as a pathogen on coriander in China. F. oxysporum is a destructive plant pathogen with an unusually broad host range and worldwide distribution, prevention and control measures should be taken in advance.

A Research on the Determination of Phenological and Molecular Characterization in Open-pollinated Genotypes in Walnut

This research was carried out to reveal the phenological and genetic differences between the S-1/1 walnut genotype and 94 F1 genotypes obtained from this genotype with each other and with the maternal parent. In the phenological observations made, it was observed that bud burst in genotypes took 52 days, leafing 50 days, leaf yellowing 31 days, and defoliation date 27 days. When the maternal parent (S-1/1) and the genotypes were compared, it was found that there was a phenological variation of 75.54 % in budburst, 73.41 % in the leafing, 34.05 % in leaf yellowing, and 93.62 % in defoliation date, while the average variation was 69.15 %. In molecular genetic analyzes, 7 ISSR primers were used to determine genetic variations, as a result, 7 monomorphic and 45 polymorphic bands were obtained, and the rate of polymorphism was found to be 86.53 %. The average number of alleles was calculated to be 7.42. In genotypes, the polymorphism information content (PIC) value varied between 0.48 and 0.95, while the average PIC value was calculated to be 0.73. As a result of cluster analysis, it was seen that genotypes were divided into 2 main clusters and 2 subsets. At the end of the study, it was determined that the S-1/1 walnut genotype and F1 genotypes obtained from this genotype have a significant variation both phenologically and genetically.

Detection and phylogeny of viruses in native Albanian olive varieties

Forty samples representing 14 native Albanian and two foreign olive varieties were collected from an olive varietal collection plot in the Valias region (Tirana, Albania). The samples were assayed by RT-PCR for presence of olive-infecting viruses, including arabis mosaic virus (ArMV), cherry leaf roll virus (CLRV), cucumber mosaic virus (CMV), olive latent ringspot virus (OLRSV), olive latent virus 1 (OLV-1), olive leaf yellowing-associated virus (OLYaV), strawberry latent ringspot virus (SLRSV) and by PCR for the bacterium Xylella fastidiosa (Xf). Ninety-eight percent of the samples were infected with at least one virus. OLYaV was the most prevalent (85% of samples), followed by OLV-1 (50%), OLRSV (48%), CMV (28%), SLRSV (3%) and CLRV (5%), whereas ArMV and Xf were absent. Fifty-five percent of the samples were infected with one virus, 13% with two viruses, 20% with three, and 5% with four. Analyses of the nucleotide sequences of the Albanian virus isolates generally showed low genetic variability, and that most were phylogenetically related to Mediterranean isolates, in particular to those from Greece and Italy. Five olive trees, representing three native cultivars (‘Managiel’, ‘Kalinjot’ and ‘Kushan-Preze’) and one foreign (‘Leccino’), were found to be plants of the Conformitas Agraria Communitatis (“CAC”) category i.e. free of ArMV, CLRV, SLRSV and OLYaV. Only one tree of the native cultivar ‘Ulliri i kuq’ was free of all tested viruses, so this is plant material of the “Virus-tested” category. Olives derived from both categories could be used for propagation of standard quality plant materiel in a future certification programme for olive in Albania. This is the first report of CLRV, OLRSV, CMV and OLV-1 in Albania. The study also reveals the precarious health status of native olive varieties in the Valias varietal collection plot. However, the discovery of six plants representing two certifiable categories is a first step in a future olive tree certification program in the country.

Virus Surveys in Olive Orchards in Greece Identify Olive Virus T, a Novel Member of the Genus Tepovirus

Field surveys were conducted in Greek olive orchards from 2017 to 2020 to collect information on the sanitary status of the trees. Using a high-throughput sequencing approach, viral sequences were identified in total RNA extracts from several trees and assembled to reconstruct the complete genomes of two isolates of a new viral species of the genus Tepovirus (Betaflexiviridae), for which the name olive virus T (OlVT) is proposed. A reverse transcription–polymerase chain reaction assay was developed which detected OlVT in samples collected in olive growing regions in Central and Northern Greece, showing a virus prevalence of 4.4% in the olive trees screened. Sequences of amplified fragments from the movement–coat protein region of OlVT isolates varied from 75.64% to 99.35%. Three olive varieties (Koroneiki, Arbequina and Frantoio) were infected with OlVT via grafting to confirm a graft-transmissible agent, but virus infections remained latent. In addition, cucumber mosaic virus, olive leaf yellowing-associated virus and cherry leaf roll virus were identified.

Isolation of Sludge Protein from Skin Fleshing Wastes by Alkaline Hydrolysis and Determining its Effects as a Fertilizer on Growth of Some Nursery Plants: A Step Towards Tanneries Waste Utilization in Pakistan.

During Leather Processing, Skin Fleshing Wastes (SFW) are usually disposed of in an open area which creates toxic hazards. In this study, (SFW) from tanneries have been hydrolyzed using two alkalis Potassium hydroxide ( 2g/ 100g of SFW ) and Sodium hydroxide ( 4g/100g of SFW) with a sufficient amount of water at 2300 F in Autoclave for two hours. Three resultant fractions fats and oil (approximately 240 g Kg-1 ), protein (approximately 554 g Kg-1 ) and sludge containing a high amount of ashes (approximately 900 g Kg-1 ) were successfully isolated respectively. The yield of fractions was calculated on the wet weight of SFW used after the removal of lime using ammonium sulphate. In this study, the isolated third fraction Fleshing Sludge (FS) from the hydrolyzed fleshing wastes used fertilizer on the six different plants on growth commonly named Ghobi, Cran Dola, Patunia, Placus, Dentist and Dalia. The observations were taken during 30 days of incubation, at the usual temperature. The application of FS in plants observed that growth was enhanced in significant proportion as compare to reference plants supplemented with commercial fertilizer except in the Ghobi sample PS1 which shows some phytotoxicity confirmed by leaf yellowing. The results revealed that the applied sludge has no adverse effect on the growth of other experimental plants. Results were taken by measuring plants according to standard methods