A new species of Batrachuperus from northwestern China

Volume: 9Start Page: 6End Page:

Comparative Transcriptome Analysis Reveals <i>OsBGs</i> and <i>OsGSLs</i> Influence Sugar Transport through Callose Metabolism under Heat Stress in Rice

Heat or high temperature stress have caused huge damage to many crops and have become the largest threat in terms of the future. Although a huge amount of research has been conducted to explore the mechanisms of heat tolerance and many achievements were accomplished, the mechanism by which how heat stress (HS) influences the yield is still unclear. In this study, RNA-seq analysis indicated that nine 1,3-β-glucanases (BGs) belonging to the carbohydrate metabolic pathway were expressed differently during heat treatment. Therefore, we identified the BGs and glucan-synthase-likes (GSLs) in three rice ecotypes and processed the analyses of gene gain and loss, phylogenetic relationship, duplication, and syntenic relationship. We found the possibility of an environmental adaption based on BGs and GSLs during evolution. Submicrostructure and dry matter distribution analysis confirmed that HS might block the endoplasmic sugar transport pathway by increasing callose synthesis, which may lead to decreased yield and quality in rice production. This study provides a new clue regarding rice yield and quality under HS and provides guidance to rice cultivation and heat tolerance breeding

Strengthened Assimilate Transport Improves Yield and Quality of Super Rice

Rice varieties with ultra-high yields play an important role in grain production and global food security. However, little information is available on the source&ndash;sink relationships that underpin the grain quality and ultra-high-yield properties. Photosynthesis, carbohydrate accumulation and allocation, vascular bundle morphology, and nutrient uptake and characteristics were, therefore, compared in two &lsquo;super rice&rsquo; varieties: Yongyou9 (control) and Yongyou12 (ultra-high yield) that differ in grain production. Yongyou12 had a significantly higher (18.8&ndash;21.4%) grain yield than Yongyou9, together with a substantial improvement in appearance-related qualities. The total dry weight and the ratio of panicle dry weight to total dry weight were significantly higher in Yongyou12 than Yongyou9, suggesting that the improved seed traits were related to higher assimilate accumulation and allocation in the ultra-high-yield variety. Yongyou12 had larger vascular bundles and greater numbers of vascular bundles in the panicle-neck internode, as well as higher levels of SUT1, SUT2, and CIN2 transcripts in the grains than Yongyou9. The contents of nitrogen, phosphorous, and potassium were similar in Yongyou12 and Yongyou9. We concluded that assimilate transport and nutrient utilization efficiency are the main factors underlying the higher yield and quality traits of the super rice variety Yongyou12

Strengthened Assimilate Transport Improves Yield and Quality of Super Rice

Rice varieties with ultra-high yields play an important role in grain production and global food security. However, little information is available on the source–sink relationships that underpin the grain quality and ultra-high-yield properties. Photosynthesis, carbohydrate accumulation and allocation, vascular bundle morphology, and nutrient uptake and characteristics were, therefore, compared in two ‘super rice’ varieties: Yongyou9 (control) and Yongyou12 (ultra-high yield) that differ in grain production. Yongyou12 had a significantly higher (18.8–21.4%) grain yield than Yongyou9, together with a substantial improvement in appearance-related qualities. The total dry weight and the ratio of panicle dry weight to total dry weight were significantly higher in Yongyou12 than Yongyou9, suggesting that the improved seed traits were related to higher assimilate accumulation and allocation in the ultra-high-yield variety. Yongyou12 had larger vascular bundles and greater numbers of vascular bundles in the panicle-neck internode, as well as higher levels of SUT1, SUT2, and CIN2 transcripts in the grains than Yongyou9. The contents of nitrogen, phosphorous, and potassium were similar in Yongyou12 and Yongyou9. We concluded that assimilate transport and nutrient utilization efficiency are the main factors underlying the higher yield and quality traits of the super rice variety Yongyou12

Abscisic Acid Improves Rice Thermo-Tolerance by Affecting Trehalose Metabolism

Heat stress that occurs during the flowering stage severely decreases the rice (Oryza sativa L.) seed-setting rate. This damage can be reversed by abscisic acid (ABA), through effects on reactive oxygen species, carbohydrate metabolism, and heat shock proteins, but the exact role of trehalose and ATP in this process remains unclear. Two rice genotypes, namely, Zhefu802 (heat-resistant plant, a recurrent parent) and its near-isogenic line (faded green leaf, Fgl, heat-sensitive plant), were subjected to 38 &deg;C heat stress after being sprayed with ABA or its biosynthetic inhibitor, fluridone (Flu), at the flowering stage. The results showed that exogenous ABA significantly increased the seed-setting rate of rice under heat stress, by 14.31 and 22.40% in Zhefu802 and Fgl, respectively, when compared with the H2O treatment. Similarly, exogenous ABA increased trehalose content, key enzyme activities of trehalose metabolism, ATP content, and F1Fo-ATPase activity. Importantly, the opposite results were observed in plants treated with Flu. Therefore, ABA may improve rice thermo-tolerance by affecting trehalose metabolism and ATP consumption

Salicylic acid reverses pollen abortion of rice caused by heat stress

Abstract Background Extremely high temperatures are becoming an increasingly severe threat to crop yields. It is well documented that salicylic acid (SA) can enhance the stress tolerance of plants; however, its effect on the reproductive organs of rice plants has not been described before. To investigate the mechanism underlying the SA-mediated alleviation of the heat stress damage to rice pollen viability, a susceptible cultivar (Changyou1) was treated with SA at the pollen mother cell (PMC) meiosis stage and then subjected to heat stress of 40 °C for 10 d until 1d before flowering. Results Under control conditions, no significant difference was found in pollen viability and seed-setting rate in SA treatments. However, under heat stress conditions, SA decreased the accumulation of reactive oxygen species (ROS) in anthers to prevent tapetum programmed cell death (PCD) and degradation. The genes related to tapetum development, such as EAT1 (Eternal Tapetum 1), MIL2 (Microsporeless 2), and DTM1 (Defective Tapetum and Meiocytese 1), were found to be involved in this process. When rice plants were exogenously sprayed with SA or paclobutrazol (PAC, a SA inhibitor) + H2O2 under heat stress, a significantly higher pollen viability was found compared to plants sprayed with H2O, PAC, or SA + dimethylthiourea (DMTU, an H2O2 and OH· scavenger). Additionally, a sharp increase in H2O2 was observed in the SA or PAC+ H2O2 treatment groups compared to other treatments. Conclusion We suggest that H2O2 may play an important role in mediating SA to prevent pollen abortion caused by heat stress through inhibiting the tapetum PCD

The Evolution and Functional Roles of miR408 and Its Targets in Plants

MicroRNA408 (miR408) is an ancient and highly conserved miRNA, which is involved in the regulation of plant growth, development and stress response. However, previous research results on the evolution and functional roles of miR408 and its targets are relatively scattered, and there is a lack of a systematic comparison and comprehensive summary of the detailed evolutionary pathways and regulatory mechanisms of miR408 and its targets in plants. Here, we analyzed the evolutionary pathway of miR408 in plants, and summarized the functions of miR408 and its targets in regulating plant growth and development and plant responses to various abiotic and biotic stresses. The evolutionary analysis shows that miR408 is an ancient and highly conserved microRNA, which is widely distributed in different plants. miR408 regulates the growth and development of different plants by down-regulating its targets, encoding blue copper (Cu) proteins, and by transporting Cu to plastocyanin (PC), which affects photosynthesis and ultimately promotes grain yield. In addition, miR408 improves tolerance to stress by down-regulating target genes and enhancing cellular antioxidants, thereby increasing the antioxidant capacity of plants. This review expands and promotes an in-depth understanding of the evolutionary and regulatory roles of miR408 and its targets in plants

Heat stress induces spikelet sterility in rice at anthesis through inhibition of pollen tube elongation interfering with auxin homeostasis in pollinated pistils

Abstract Background Pollen tube elongation in the pistil is a key step for pollination success in plants, and auxins play an important role in this process. However, the function of auxins in pollen tube elongation in the pistil of rice under heat stress has seldom been previously reported. Results Two rice genotypes differing in heat tolerance were subjected to heat stress of 40 °C for 2 h after flowering. A sharp decrease in spikelet fertility was found in the Nipponbare (NPB) and its mutant High temperature susceptible (HTS) under heat stress, but the stress-induced spikelet sterility was reversed by 1-naphthaleneacetic acid (NAA), especially the HTS. Under heat stress, the pollen tubes of NPB were visible in ovule, while those of HTS were invisible. However, we found the pollen tubes in ovule when sprayed with NAA. During this process, a significant increase in indole-3-acetic acid (IAA) and reactive oxygen species (ROS) levels was found in the pistil of heat-stressed NPB, while in heat-stressed HTS they were obviously decreased. Additionally, the peroxidase (POD) activity in pistil of NPB was significantly decreased by heat stress, whereas there was no difference between the heat-stressed and non-heat-stressed pistils of HTS. Conclusion It was concluded that the enhancement of heat tolerance in plants by NAA was achieved through the increase of the levels of auxins, which prevented the inhibition of pollen tube elongation in pistil, and the crosstalk between auxins and ROS, which might be involved in this process. In addition, POD might be a negative mediator in pollen tube elongation under heat stress due to its ability to scavenge ROS and degrade auxin

Heat Stress Is More Damaging to Superior Spikelets than Inferiors of Rice (Oryza sativa L.) due to Their Different Organ Temperatures

In general, the fertility and kernel weight of inferior spikelets of rice (Oryza Sativa L.) are obviously lower than those of superior spikelets, especially under abiotic stress. However, heat stress at anthesis seems to cause more damage to superior spikelets than to inferior spikelets.When rice plants were subjected to heat stress of 40℃ at anthesis, a greater decrease in fertility and kernel weight was observed in superior spikelets compared to inferior spikelets. This decrese has primarily been described to their different organ temperatures, in which the temperature of the superior spikelets was significantly higher than that of inferior spikelets. We inferred the differences in canopy temperature, light intensity and panicle types, were the primary reasons for the temperature difference between superior and inferior spikelets.Under heat stress, the fertility and kernel weight of superior and inferior spikelets decreased as the panicle numbers per plant were reduced, which was accompanied by the significantly increased canopy temperatures. Thus, it was suggested that the rice plant with characteristic features of an upright growth habit and loose panicles might be more susceptible to heat stress resulting from their higher canopy and spikelets temperatures

Oligomeric Proanthocyanidins Confer Cold Tolerance in Rice through Maintaining Energy Homeostasis

Oligomeric proanthocyanidins (OPCs) are abundant polyphenols found in foods and botanicals that benefit human health, but our understanding of the functions of OPCs in rice plants is limited, particularly under cold stress. Two rice genotypes, named Zhongzao39 (ZZ39) and its recombinant inbred line RIL82, were subjected to cold stress. More damage was caused to RIL82 by cold stress than to ZZ39 plants. Transcriptome analysis suggested that OPCs were involved in regulating cold tolerance in the two genotypes. A greater increase in OPCs content was detected in ZZ39 than in RIL82 plants under cold stress compared to their respective controls. Exogenous OPCs alleviated cold damage of rice plants by increasing antioxidant capacity. ATPase activity was higher and poly (ADP-ribose) polymerase (PARP) activity was lower under cold stress in ZZ39 than in RIL82 plants. Importantly, improvements in cold tolerance were observed in plants treated with the OPCs and 3-aminobenzamide (PARP inhibitor, 3ab) combination compared to the seedling plants treated with H2O, OPCs, or 3ab alone. Therefore, OPCs increased ATPase activity and inhibited PARP activity to provide sufficient energy for rice seedling plants to develop antioxidant capacity against cold stress