Possible Overestimation of Seed Transmission in the Spread of Pospiviroids in Commercial Pepper and Tomato Crops Based on Large-Scale Grow-Out Trials and Systematic Literature Review

International Trade and Local Effects of Viral and Bacterial Diseases in Ornamental Plants

Since the 1950s, there have been major changes in the scope, value, and organization of the ornamental plant industry. With fewer individual producers and a strong trend toward consolidation and globalization, increasing quantities of diverse plant genera and species are being shipped internationally. Many more ornamentals are propagated vegetatively instead of by seed, further contributing to disease spread. These factors have led to global movement of pathogens to countries where they were not formerly known. The emergence of some previously undescribed pathogens has been facilitated by high-throughput sequencing, but biological studies are often lacking, so their roles in economic diseases are not yet known. Case studies of diseases in selected ornamentals discuss the factors involved in their spread, control measures to reduce their economic impact, and some potential effects on agronomic crops. Advances in diagnostic techniques are discussed, and parallels are drawn to the international movement of human diseases.

Epidemiology and Control of Plant Diseases

I am pleased to present this edition of the Special Issue of Plants, dedicated to multifaceted topic of epidemiology and control of plant diseases in agricultural systems [...].

Molecular detection and characterization of Potato spindle tuber viroid (PSTVd) infecting Tomato (Solanum lycopersicum L.) in Karnataka State of India

Potato Spindle Tuber Viroid (PSTVd) is a non-coding, infectious, small, circular RNA known to cause disease in agricultural and horticultural plants. In the present work, an investigation was conducted in the southern districts of Karnataka state to assess the possible pospiviroid infections on tomato plants that are considered natural hosts for viroids. A total of 83 tomato samples showing disease symptoms (virus or viroid-like) along with healthy ones were collected and subjected to viroid detection by conventional Reverse Transcriptase Polymer Chain Reaction (RT-PCR) using universal (Pospi1-RE/Pospi1-FW) and a specific set of primers (3H1/2H1). The study confirmed the presence of PSTVd in one of the samples of tomato collected from Banghatta village of Mandy District, with an expected amplicon of ~ 361 bp. The bioassay conducted on tomato plants (cv. Rutgers) proved the association of PSTVd, which was further confirmed by RT-PCR. The amplicons were cloned, sequenced, and the representative sequences were deposited in the NCBI GenBank. The sequence alignment and secondary structure analysis of the isolated viroid with other reference sequences revealed the variations in the pathogenicity, central conserved region, and Terminal right domains. The variations observed between the isolated PSTVd with that of other Indian isolates support that viroid may have been transmitted among the crop plants, possibly through seed or mechanical means.