Abiotic stresses, such as drought, high temperature, and salinity, affect plant growth and productivity. Furthermore, global climate change may increase the frequency and severity of abiotic stresses, suggesting that development of varieties with improved stress tolerance is critical for future sustainable crop production. Improving stress tolerance requires a detailed understanding of the hormone signaling and transcriptional pathways involved in stress responses. Abscisic acid (ABA) and jasmonic acid (JA) are key stress-response hormones in plants, and some stress-responsive transcription factors such as ABFs and MYCs function as direct components of ABA and JA signaling, playing a pivotal role in plant tolerance to abiotic stress. In addition, extensive studies have identified other stress-responsive transcription factors belonging to the NAC, AP2/ERF, MYB, and WRKY families that mediate plant response and tolerance to abiotic stress. These suggest that transcriptional regulation of stress-responsive genes is an essential step to determine the mechanisms underlying plant stress responses and tolerance to abiotic stress, and that these transcription factors may be important targets for development of crops with enhanced abiotic stress tolerance. In this review, we briefly describe the mechanisms underlying plant abiotic stress responses, focusing on ABA and JA metabolism and signaling pathways. We then summarize the diverse array of transcription factors involved in plant responses to abiotic stress, while noting their potential applications for improvement of stress tolerance.

To date, extensive studies have identified many classes of hormones in plants and revealed the specific, nonredundant signaling pathways for each hormone. However, plant hormone functions largely overlap in many aspects of plant development and environmental responses, suggesting that studying the crosstalk among plant hormones is key to understanding hormonal responses in plants. The phytohormone jasmonic acid (JA) is deeply involved in the regulation of plant responses to biotic and abiotic stresses. In addition, a growing number of studies suggest that JA plays an essential role in the modulation of plant growth and development under stress conditions, and crosstalk between JA and other phytohormones involved in growth and development, such as gibberellic acid (GA), cytokinin, and auxin modulate various developmental processes. This review summarizes recent findings of JA crosstalk in the modulation of plant growth and development, focusing on JA–GA, JA–cytokinin, and JA–auxin crosstalk. The molecular mechanisms underlying this crosstalk are also discussed.

The phytohormone jasmonic acid (JA), a cyclopentane fatty acid, mediates plant responses to abiotic stresses. Abiotic stresses rapidly and dynamically affect JA metabolism and JA responses by upregulating the expression of genes involved in JA biosynthesis and signaling, indicating that JA has a crucial role in plant abiotic stress responses. The crucial role of JA has been demonstrated in many previous studies showing that JA response regulates various plant defense systems, such as removal of reactive oxygen species and accumulation of osmoprotectants. Furthermore, increasing evidence shows that plant tolerance to abiotic stresses is linked to the JA response, suggesting that abiotic stress tolerance can be improved by modulating JA responses. In this review, we briefly describe the JA biosynthetic and signaling pathways and summarize recent studies showing an essential role of JA in plant responses and tolerance to a variety of abiotic stresses, such as drought, cold, salt, and heavy metal stress. Additionally, we discuss JA crosstalk with another key stress hormone, abscisic acid, in plant abiotic stress responses.

Exosomes are nano-sized extracellular vesicles that regulate cell growth and defense by delivering bioactive cellular constituents. They are a promising material for biomedical and cosmetic utilization, especially in medicinal crops such as ginseng. One main hurdle to their usage is the need for a method to isolate stable exosomes with high purity. In this study, we first tested two methods to isolate exosomes from ginseng: ultracentrifugation, the most widely used method; and the ExoQuick system, a polymer-based exosome precipitation approach. We also designed and tested a third method in which we combined ultracentrifugation and ExoQuick methods. Size distribution analysis revealed that the exosome isolation purity by the ultracentrifugation and ExoQuick methods alone were 34.1% and 59.7%, respectively, while the combination method greatly improved exosome isolation purity (83.3%). Furthermore, we found that the combination method also increases the colloidal stability of isolated ginseng exosomes, and the increase was almost double that of the ultracentrifugation method. Lastly, we showed that the combination method can also be used to isolate high-purity and high-stability exosomes from the model plant Arabidopsis. Overall, our findings indicate that the combination method is suitable to isolate high-purity and high-stability exosomes from plants including ginseng.

Roots anchor plants and take up water and nutrients from the soil; therefore, root development strongly affects plant growth and productivity. Moreover, increasing evidence indicates that root development is deeply involved in plant tolerance to abiotic stresses such as drought and salinity. These findings suggest that modulating root growth and development provides a potentially useful approach to improve plant abiotic stress tolerance. Such targeted approaches may avoid the yield penalties that result from growth–defense trade-offs produced by global induction of defenses against abiotic stresses. This review summarizes the developmental mechanisms underlying root development and discusses recent studies about modulation of root growth and stress tolerance in rice.

The transition from the vegetative to the reproductive stage of growth is a critical event in the lifecycle of a plant and is required for the plant’s reproductive success. Flowering time is tightly regulated by an internal time-keeping system and external light conditions, including photoperiod, light quality, and light quantity. Other environmental factors, such as drought and temperature, also participate in the regulation of flowering time. Thus, flexibility in flowering time in response to environmental factors is required for the successful adaptation of plants to the environment. In this review, we summarize our current understanding of the molecular mechanisms by which internal and environmental signals are integrated to regulate flowering time in Arabidopsis thaliana and rice (Oryza sativa).