Bacterial panicle blight of rice (BPBR) is one of the most important diseases of rice; it seriously threatens the high and stable yield of rice in the world. Although the disease is still listed as a quarantine disease in China, recent studies have shown that BPBR can spread at any time. Therefore, in addition to strengthening quarantine work, targeted control technology research is needed. During the process of infection, Burkholderia glumae has evolved multiple virulence factors. However, at the same time, rice has evolved a variety of defense mechanisms during the long-term interaction between rice and pathogens. Resistance genes are one of the main defense mechanisms. Therefore, mining the resistance locus of BPBR on the rice genome and breeding resistant varieties is the safest and most effective way to control the disease. To provide references for excavation and separation resistance sites, this paper reviews the pathogenic characteristics, pathogenesis, disease cycle and rice resistance to BPBR.

Rice blast, caused by Magnaporthe oryzae, is one of the most destructive diseases of rice worldwide. The identification and utilization of resistance genes are the basis and key factors for breeding resistance rice cultivars. With the availability of genomic sequences of both Oryza sativa and M. oryzae, rice has become one of the model systems for dissecting the molecular interactions between plants and pathogens. In this paper, we summarize the current status of genetics, mapping, cloning and breeding application of the genes resistant to blast. Using bioinformatics analysis, we analyzed the distribution of all NBS-LRR type of disease resistance genes on the 12 chromosomes of the rice genome and also preliminarily summarized the identified avirulence genes as well as interactions between the resistance proteins and the avirulence proteins. Finally, we analyzed and discussed the problems in rice breeding and prospects for research. This review will provide useful suggestions for further research on rice blast resistance breeding and disease resistance mechanisms.

Plants have evolved numerous strategies to adapt to complex and changing surroundings. Plants have a wide range of systemic responses induced by local stresses to precisely regulate plant growth, development and adaptability to environments. Plant systemic responses induce whole-plant signaling transmission at first, called systemic signaling. When subjected to local stresses, plants trigger chemical molecules in local cells, such as biosynthesis and/or signaling transduction of the phytohormones jasmonic acid and methyl salicylate. Accompanied by a series of complex signal cascades, multiple signal components work together to activate the systemic response. In the past several years, pioneer studies demonstrated that phytohormones, small peptides and several types of RNAs are considered key components of slow-moving systemic signaling, and rapid systemic signals include reactive oxygen species, calcium signals and electrical signals. Plant systemic signaling is essential for plant growth, development and adaptation to the environment, and the precise transmission mechanism is worthy of further investigation. In this review, we describe the research progress in plant systemic signaling transmission and response to the environment and summarize several key systemic signal components and their transmission mechanism. Finally, the potential challenges of future research in this research field are discussed.

Phosphatidic acid (PA), a second messenger, is considered to be a lipid signal whose level increases transiently in response to various challenges. The main production of PA derives from phospholipase D (PLD) and phospholipase C/diacylglycerol kinase (PLC/DGK) pathways. On the basis of differences in biochemical properties, catalytic mechanisms, and heterogeneities of PLDs, which are activated under specific stress, diverse PA molecular species composition would be formed response to various stresses conditions. PA is involved in various physiological processes. It acts as messenger by binding target proteins and regulating proteins positively and negatively in stomatal closure pathways. In this review, we first summarize biochemical properties of PA and the effects of PA on protein interaction and then provide insights into some crucial and urgent issues as well as directions for future research.

Frost has had a prominent influence on the fruit industry in China in recent years. We need to establish a system to simulate frost treatment for fruit trees. Based on observations of frost events in field, we analyzed the characteristics of frost in terms of cooling rate, the low temperature limit, warming rate, and light conditions after frost treatment and established a system to simulate frost treatment in the laboratory. Temperature during the frost treatment in field could be divided into three stages: cooling, extreme temperature maintenance and warming. The temperature during cooling and warming stages changed in an approximately linear manner. Frost is generally followed by high intensity light. The simulated frost process was determined as followed: the temperature drops from room temperature (20°C) to 5°C in 30 min, and is maintained at 5°C for 30 min, then decreases to -2°C at a rate of 0.8°C·h ^-1, is maintained at -2°C for 2 h, then increases to 5°C at a rate of 4.7°C·h ^-1 in the dark. The recovery condition after frost was 16°C and 800 μmol·m ^-2·s ^-1.

Peach (Amygdalus persica) seedlings were used to analyze the effect of ammonium molybdate on the expression of molybdenum cofactor sulfurase gene (LOS5/ABA3), ABA content and physiological indexes related to drought resistance under drought stress. Water, chlorophyll and proline contents of peach seedling leaves were significantly higher with ammonium molybdate, preferably 0.04%, than control treatment, and electrolyte leakage was lower. Under drought stress, the expression of LOS5/ABA3 in leaves treated with 0.04% ammonium molybdate was significantly increased and ABA content, water use efficiency, and net photosynthetic rate was higher than with control treatment. Transpiration rate was lower, antioxidant enzyme activity was higher, and malondialdehyde content was lower in leaves; the quality loss of leaves in vitro was reduced. Thus, ammonium molybdate treatment of peach seedlings can increase the content of ABA and proline, increase the activity of antioxidant enzymes, relieve cell membrane oxidation damage, decrease the rate of water loss of leaves, and alleviate drought stress damage by regulating the expression of drought- resistant genes, then increase the drought resistance of plants.

Geranylgerany pyrophosphate synthase (GGPPS) is an important regulator in the plant diterpenoid biosynthesis pathway. The GGPPS gene family plays a critical role in the development of the medicinal model plant Salvia miltiorrhiza. However, the biological function of SmGGPPS2, especially in the biosynthesis of tanshinone or other active ingredients, is still unclear. For functional investigation, SmGGPPS2 expression was up- or down-regulated in S. miltiorrhiza plants via overexpression or RNA interference, respectively. Then we detected the content of tanshinones, the expression of genes related to tanshinone biosynthesis, and the physiological indexes of transgenic S. miltiorrhiza plants. The content of fat-soluble components, such as tanshinone IIA and ferruginol, was increased significantly in SmGG- PPS2-overexpressed lines compared with the wild type, and the content of fat soluble-components was lower in SmGGPPS2-RNAi lines than those in the wild type lines. With the regulation of SmGGPPS2, the expression of key enzyme genes related to tanshinone biosynthesis in S. miltiorrhiza, such as SmHMGR1 and SmCPS1, was changed. In addition, the regulation of SmGGPPS2 expression also affected the resistance of S. miltiorrhiza. Our results indicate that SmGGPPS2 plays an important regulatory role in tanshinone biosynthesis.

We investigated the salt-tolerant mechanism of cottonseed meal in cotton (Gossypium hirsutum) under sali- nity-alkalinity stress. Salinity-alkalinity stress of 8 g·kg ^-1was tested in the field to explore the effect of cottonseed meal dose on the physiology and growth of cotton. Cottonseed meal could increase the absorption of K ⁺ and decrease that of Na ⁺. K ⁺ and Na ⁺ were kept in ion balance in cells under salinity-alkalinity stress. Cottonseed meal could effectively alleviate damage to cotton, significantly promote growth of cotton, and improve chlorophyll content and photosynthesis of leaves. An amount of 6 000 kg·hm ^-2 cottonseed meal was the most significant treatment, and the improvement effect of cottonseed meal under salt stress was better. According to principal component analysis, the K ⁺/Na ⁺ratio in leaves, root length, fresh weight, dry weight and intercellular CO₂ concentration were the main factors involved in salinity-alkalinity stress.

In order to identify long-distance signals under iron (Fe) deficiency in rice (Oryza sativa), TMT label technique was used to study the protein profile of phloem sap under different iron concentrations. A total of 206 differentially ex- pressed proteins were identified: 54 were upregulated and 152 were downregulated. Most of these proteins are involved in hormone signal transduction, carbon metabolism, glutathione metabolism and mRNA transport. In addition, we mea- sured the physiological indicators according to the differentially expressed proteins. It was found that phytohormones, sucrose, glutathione and transporters were significantly changed under iron deficiency. To further study the function of these proteins can help to reveal the long distance signaling pathway of rice in response to Fe deficiency.

Brassinosteroids (BRs) are a class of steroid phytohormones that play diverse roles in plant growth and development and stress responses. Rapid progresses have been made in how BRs regulate plant growth and development in recent years. However, the roles of BRs in stress response in Oryza sativa remain unclear. Here, we investigated the relation between salinity stress and BR synthesis in rice. Both salt stress and abscisic acid, the well-known stress hormone, strongly inhibited the expression of two BR-synthetic genes, D2 and D11. In addition, both d2-2, the BR synthetic mutant, and d61-1, the BR receptor mutant, showed impaired tolerance to salt stress. Moreover, by using transgenic plants overexpressing OsBZR1, the key BR signaling transcriptional factor, we found that BRs strongly induced dephosphorylation of OsBZR1, but high concentrations of salt suppressed OsBZR1 protein accumulation as well as its dephosphorylation. Furthermore, transcriptome analyses revealed that 38.4% of BR-regulated genes were also regulated by high concentrations of salt, and importantly, 91.5% of the co-regulated genes are consistently up- or downregulated by both BR and salt. Gene Ontology analyses revealed that these overlapping genes were highly enriched in the biological process “response to stimulus”. Taken together, our results suggest that BRs contribute to salt stress tolerance, and salt stress suppresses BR synthesis to restrict rice growth.

Reversible protein phosphorylation is a common mechanism regulating plant signaling pathways. Phosphorylation of key components in plant-pathogen interactions affects the activation of defense signaling. Many pathogens attack the plant immune system and enhance pathogenic toxicity by disturbing the phosphorylation status of defense regulators. In this review, we summarize the phosphorylation of regulators in plant defense responses and its regulating effect in plant immunity. Understanding the phosphorylation of key regulators in the plant-pathogen interaction may help to explore new mechanism of plant immune regulation. This review may provide support and a basis for studying new approaches of broad-spectrum disease resistance.

As a consequence of global warming, crops face more acute and more frequent high-temperature stress. Heat threatens the whole plant development, especially pollen development, which seems to be the most sensitive process in the plant life cycle. Hence, the mechanism underlying the pollen response to heat stress has become a hot topic in the field of plant biology. Recent studies have revealed that pollen has at least 4 ways to perceive the heat stress signal: calcium channels, unfolded protein response, reactive oxygen species and H2A.Z. Pollen responds to heat stress by regulating heat shock protein expression, glycol-metabolism and phytohormone level and enhancing reactive oxygen species scavenging capacity. In this review, we summarize pollen development defects under heat stress, the mechanism of pollen thermotolerance and discuss how to design the experiments to study pollen thermotolerance. The overview provides guidelines for the pollen heat response mechanism in crops.

Nucleotide binding, leucine-rich repeat (NLR) immune receptors are a major family of plant resistance (R) proteins, which are also found in animals. NLRs turn on immune signaling by recognizing pathogen-specific effectors in plants. Although the first few plant NLR R genes were cloned more than 25 years ago, the activation mechanism remained elusive. No structure is available for the full-length plant NLRs despite attempts over the last 2 decades. Recently, studies from the Chai, Zhou and Wang labs, published in Science, solved the structure of zygote arrest 1 (ZAR1) before and after effector recognition, which fills a huge gap in NLR biology. This mini review briefly summarized these findings and related progresses, and highlighted further challenges in NLR-mediated immune signaling field.

In this study, we examined the inhibitory effects of natamycin at different concentrations on the conidial germination and mycelial growth of Colletotrichum gloeosporioides in vitro as well as the controlled effect of natamycin on postharvest anthracnose of mango (Mangifera indica) fruit inoculated with C. gloeosporioides. To further explore the underlying antifungal mechanism, we analyzed the membrane permeability, soluble protein content, changes in cell membrane integrity, intracellular reactive oxygen species (ROS) level and mitochondrial distribution in C. gloeosporioides after natamycin treatment. Natamycin at 3 mg∙L ^-1 effectively suppressed the conidial germination, germ tube elongation and mycelial growth of C. gloeosporioides. Also, 80 mg∙L ^-1natamycin significantly inhibited the expansion of anthracnose lesions in mango fruit during storage. Furthermore, natamycin treatment increased the relative permeability and soluble protein content in the cell membrane of C. gloeosporioides. After 8h treatment with natamycin 2 mg∙L ^-1, the staining rate of damaged cell membranes in C. gloeosporioides was 33.6% and 13.9% in the control. The staining rate of intracellular ROS reached 46.9% in treated conidia, which was 39.7% higher than that of the control. Natamycin treatment caused heterogeneous distribution of intracellular mitochondria along with weaker fluorescence as compared with the control. In summary, natamycin can destroy the cell membrane of C. gloeosporioides, induce ROS accumulation and reduce mitochondrial activity, thus interfering in the normal physiological activity of C. gloeosporioides and affecting its metabolic activities.

The premise of studies on rice chilling tolerance is to find an efficient and accurate way to evaluate chilling tolerance of rice seedling. In this study, we developed an efficient technology to evaluate the cold tolerance at seedling stage by using a constant temperature water bath, based on the characteristics of excellent temperature uniformity for circulation of water. In this method, the setting temperature of environment temperature and water bath was 20°C and 4°C, respectively. From the results of two subspecies (indica/xian and japonica/geng), we summarized the reference treatment time for different survival rate of cultivars. Some attention to the cold treatment procedure was also discussed.