Jasmonates Alleviate the Harm of High-Temperature Stress During Anthesis to Stigma Vitality of Photothermosensitive Genetic Male Sterile Rice Lines

Exogenous Methyl Jasmonate Mediated MiRNA-mRNA Network Improves Heat Tolerance of Perennial Ryegrass

Heat stress can hinder the growth of perennial ryegrass (Lolium perenne L.). Methyl jasmonate (MeJA) applied exogenously can increase heat stress tolerance in plants; however, the regulatory mechanisms involved in heat tolerance mediated by MeJA are poorly understood in perennial ryegrass. Here, the microRNA (miRNA) expression profiles of perennial ryegrass were assessed to elucidate the regulatory pathways associated with heat tolerance induced by MeJA. Plants were subjected to four treatments, namely, control (CK), MeJA pre-treatment (T), heat stress treatment (H), and MeJA pre-treatment + heat stress (TH). According to the results, 102 miRNAs were up-regulated in all treatments, with 20, 27, and 33 miRNAs being up-regulated in the T, H, and TH treatment groups, respectively. The co-expression network analysis between the deferentially expressed miRNAs and their corresponding target genes showed that 20 miRNAs modulated 51 potential target genes. Notably, the miRNAs that targeted genes related to with regards to heat tolerance were driven by MeJA, and they were involved in four pathways: novel-m0258-5p mediated signal transduction, novel-m0350-5p mediated protein homeostasis, miR397-z, miR5658-z, and novel-m0008-5p involved in cell wall component, and miR1144-z and miR5185-z dominated chlorophyll degradation. Overall, the findings of this research paved the way for more research into the heat tolerance mechanism in perennial ryegrass and provided a theoretical foundation for developing cultivars with enhanced heat tolerance.

Advances on the Study of Diurnal Flower-Opening Times of Rice

The principal goal of rice (Oryza sativa L.) breeding is to increase the yield. In the past, hybrid rice was mainly indica intra-subspecies hybrids, but its yield has been difficult to improve. The hybridization between the indica and japonica subspecies has stronger heterosis; the utilization of inter-subspecies heterosis is important for long-term improvement of rice yields. However, the different diurnal flower-opening times (DFOTs) between the indica and japonica subspecies seriously reduce the efficiency of cross-pollination and yield and increase the cost of indica-japonica hybrid rice seeds, which has become one of the main constraints for the development of indica-japonica hybrid rice breeding. The DFOT of plants is adapted to their growing environment and is also closely related to species stability and evolution. Herein, we review the structure and physiological basis of rice flower opening, the factors that affect DFOT, and the progress of cloning and characterization of DFOT genes in rice. We also analyze the problems in the study of DFOT and provide corresponding suggestions.

High-temperature stress in crops: male sterility, yield loss and potential remedy approaches

Global food security is one of the utmost essential challenges in the 21st century in providing enough food for the growing population while coping with the already stressed environment. High temperature (HT) is one of the main factors affecting plant growth, development and reproduction and causes male sterility in plants. In male reproductive tissues, metabolic changes induced by HT involve carbohydrates, lipids, hormones, epigenetics and reactive oxygen species, leading to male sterility and ultimately reducing yield. Understanding the mechanism and genes involved in these pathways during the HT stress response will provide a new path to improve crops by using molecular breeding and biotechnological approaches. Moreover, this review provides insight into male sterility and integrates this with suggested strategies to enhance crop tolerance under HT stress conditions at the reproductive stage.

Responses of differential metabolites and pathways to high temperature in cucumber anther

Cucumber is one of the most important vegetable crops, which is widely planted all over the world. Cucumber always suffers from high-temperature stress in South China in summer. In this study, liquid chromatography-mass spectrometry (LC-MS) analysis was used to study the differential metabolites of cucumber anther between high-temperature (HT) stress and normal condition (CK). After HT, the pollen fertility was significantly reduced, and abnormal anther structures were observed by the paraffin section. In addition, the metabolomics analysis results showed that a total of 125 differential metabolites were identified after HT, consisting of 99 significantly upregulated and 26 significantly downregulated metabolites. Among these differential metabolites, a total of 26 related metabolic pathways were found, and four pathways showed significant differences, namely, porphyrin and chlorophyll metabolism; plant hormone signal transduction; amino sugar and nucleotide sugar metabolism; and glycine, serine, and threonine metabolism. In addition, pollen fertility was decreased by altering the metabolites of plant hormone signal transduction and amino acid and sugar metabolism pathway under HT. These results provide a comprehensive understanding of the metabolic changes in cucumber anther under HT.

Plant hormones and neurotransmitter interactions mediate antioxidant defenses under induced oxidative stress in plants

Due to global climate change, abiotic stresses are affecting plant growth, productivity, and the quality of cultivated crops. Stressful conditions disrupt physiological activities and suppress defensive mechanisms, resulting in stress-sensitive plants. Consequently, plants implement various endogenous strategies, including plant hormone biosynthesis (e.g., abscisic acid, jasmonic acid, salicylic acid, brassinosteroids, indole-3-acetic acid, cytokinins, ethylene, gibberellic acid, and strigolactones) to withstand stress conditions. Combined or single abiotic stress disrupts the normal transportation of solutes, causes electron leakage, and triggers reactive oxygen species (ROS) production, creating oxidative stress in plants. Several enzymatic and non-enzymatic defense systems marshal a plant's antioxidant defenses. While stress responses and the protective role of the antioxidant defense system have been well-documented in recent investigations, the interrelationships among plant hormones, plant neurotransmitters (NTs, such as serotonin, melatonin, dopamine, acetylcholine, and γ-aminobutyric acid), and antioxidant defenses are not well explained. Thus, this review discusses recent advances in plant hormones, transgenic and metabolic developments, and the potential interaction of plant hormones with NTs in plant stress response and tolerance mechanisms. Furthermore, we discuss current challenges and future directions (transgenic breeding and genome editing) for metabolic improvement in plants using modern molecular tools. The interaction of plant hormones and NTs involved in regulating antioxidant defense systems, molecular hormone networks, and abiotic-induced oxidative stress tolerance in plants are also discussed.