The Intriguing Conundrum of a Nonconserved Multifunctional Protein of Citrus Tristeza Virus That Interacts with a Viral Long Non-Coding RNA

Long Noncoding RNAs in Plant-Pathogen Interactions

Long noncoding RNAs (lncRNAs) are commonly defined as transcripts that lack protein-coding capacity and are longer than 200 nucleotides. Since the emergence of next-generation sequencing technologies in this century, thousands of lncRNAs have been identified from nearly all living organisms. Notably, various pathogens also express their own lncRNAs in host cells during infection. In plants, many lncRNAs exhibit dynamic expression patterns in response to environmental stimuli, including pathogen attacks. In contrast to well-established methods in identifying such lncRNAs, the current understanding of lncRNAs' functional mechanisms is in its infancy. Some lncRNAs serve as precursors for generating small RNAs or serve as target mimics to sequester functional small RNAs, which have been extensively reviewed in the literature. This review focuses on the emerging evidence supporting that certain lncRNAs function as negative or positive regulators of plant immunity. A common theme is that those regulations rely on specific interactions between lncRNAs and key regulatory proteins. Viroids as single-stranded circular noncoding RNAs provide a handle to investigate how RNA local motifs render interaction specificity between lncRNAs and regulatory proteins. [Formula: see text] Copyright © 2023 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Long Non-Coding RNAs of Plants in Response to Abiotic Stresses and Their Regulating Roles in Promoting Environmental Adaption

Abiotic stresses triggered by climate change and human activity cause substantial agricultural and environmental problems which hamper plant growth. Plants have evolved sophisticated mechanisms in response to abiotic stresses, such as stress perception, epigenetic modification, and regulation of transcription and translation. Over the past decade, a large body of literature has revealed the various regulatory roles of long non-coding RNAs (lncRNAs) in the plant response to abiotic stresses and their irreplaceable functions in environmental adaptation. LncRNAs are recognized as a class of ncRNAs that are longer than 200 nucleotides, influencing a variety of biological processes. In this review, we mainly focused on the recent progress of plant lncRNAs, outlining their features, evolution, and functions of plant lncRNAs in response to drought, low or high temperature, salt, and heavy metal stress. The approaches to characterize the function of lncRNAs and the mechanisms of how they regulate plant responses to abiotic stresses were further reviewed. Moreover, we discuss the accumulating discoveries regarding the biological functions of lncRNAs on plant stress memory as well. The present review provides updated information and directions for us to characterize the potential functions of lncRNAs in abiotic stresses in the future.

Viral long non-coding RNA regulates virus life-cycle and pathogenicity

Viral infection is still a serious global health problem that kills hundreds of thousands of people annually. Understanding the mechanism by which virus replicates, packages, and infects the host cells can provide new strategies to control viral infection. Long non-coding RNAs (lncRNAs) have been identified as critical regulators involved in viral infection process and antiviral response. A lot of host lncRNAs have been identified and shown to be involved in antiviral immune response during viral infection. However, our knowledge about lncRNAs expressed by viruses is still at its infancy. LncRNAs expressed by viruses are involved in the whole viral life cycle, including promoting genome replication, regulating gene expression, involvement in genome packaging, assembling new viruses and releasing virions to the host cells. Furthermore, they enhance the pathogenicity of viral infections by down-regulating the host cell's antiviral immune response and maintain the viral latency through a refined procedure of genome integration. This review focuses on the regulatory roles of viral lncRNA in the life-cycle and pathogenicity of viruses. It gives an insight into the viral lncRNAs that can be utilized as therapeutic targets against viral diseases, and future researches aimed to identify and explore new viral lncRNAs and the mechanisms of their involvement in viral infection is encouraged.

Citrus Tristeza Virus: From Pathogen to Panacea

Citrus tristeza virus (CTV) is the most destructive viral pathogen of citrus. During the past century, CTV induced grave epidemics in citrus-growing areas worldwide that have resulted in a loss of more than 100 million trees. At present, the virus continues to threaten citrus production in many different countries. Research on CTV is accompanied by distinctive challenges stemming from the large size of its RNA genome, the narrow host range limited to slow-growing Citrus species and relatives, and the complexity of CTV populations. Despite these hurdles, remarkable progress has been made in understanding the CTV-host interactions and in converting the virus into a tool for crop protection and improvement. This review focuses on recent advances that have shed light on the mechanisms underlying CTV infection. Understanding these mechanisms is pivotal for the development of means to control CTV diseases and, ultimately, turn this virus into an ally.

Expected final online publication date for the Annual Review of Virology, Volume 9 is September 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.