Application of brassinolide alleviates cold stress at the booting stage of rice

The objective of the study was to determine the physiological mechanisms of plants in response to brassinolide(BR) alleviating cold water stress on rice. In this study, physiological responses of rice to exogenous BR and cold water submergence were investigated using the chilling-tolerant cultivar Kongyu 131(KY131) and the chilling-sensitive cultivar Kenjiandao 6(KJD6). A total of 2 mg L^-1 BR increased activities of superoxide dismutase(SOD) and peroxidase(POD) and the contents of soluble sugar, soluble protein, and chlorophyll, but decreased the malondialdehyde(MDA) content in KY131 and KJD6 under cold water stress. The observed decreases in SOD and POD activities and MDA content recovered quickly after plants were returned to irrigation with water at temperatures of about 23.0°C in 2014. Additionally, the contents of nitrogen(N), phosphorous(P), and potassium(K) were increased by BR treatment under cold water stress. Exposure to BR also raised the percentage of high effective leaf area and leaf area index at the heading stage. Furthermore, it promoted soluble sugar synthesis, increased the rate of dry matter accumulation, and enhanced the export and translocation rates of the stem-sheath. The yield in KJD6 was significantly(P≤0.01 and P≤0.05) higher than that of the control in 2013 and 2014, respectively. The effect of BR treatment on rice leaf SOD and POD activities, MDA, chlorophyll, P, and stem-sheath K contents were more significant in KJD6 than in KY131. In conclusion, exogenous BR effectively reduced the physiological and metabolic damage in rice due to cold stress at the booting stage, promoted functional recovery in plants that received irrigation with water at a normal temperature following cold stress, and mitigated the effects of cold water stress on yield.The two varieties exhibited differential responses to BR;the weaker cold-resistant variety was more sensitive to BR and displayed stronger responses to exogenous BR.

Protective Roles of Brassinolide on Rice Seedlings under High Temperature Stress

Two indica rice （Oryza sativa L.） materials, Xieqingzao B （sensitive to heat stress） and 082 （tolerant to heat stress） were used to study the role of brassinolide （BR） in protection of rice seedlings from heat stress. Young seedlings were subjected to high temperature （38℃/30℃） and sprayed with 0.005 mg/L of BR. Analysis was conducted on the contents of chlorophyll, protein and malondialdehyde （MDA）, the leakage of electrolyte, the activities of peroxidase （POD） and superoxide dismutase （SOD） and their isozymes expression levels in leaves. Under the high temperature treatment, application of BR significantly increased the contents of chlorophyll and protein, and the activities of POD and SOD, and reduced the content of MDA and the leakage of electrolyte in the leaves of the heat-sensitive material Xieqingzao B, whereas BR had less effect on those of the heat-tolerant material 082 relatively. The BR treatment enhanced the expression of POD isozymes in the leaves of both materials. Under the high temperature stress and BR treatment, the expression of four SOD isozymes reduced in 082, but the expression of two SOD isozymes increased in Xieqingzao B. This suggests that BR plays an important role in protection of rice seedlings from heat stress by enhancing the activities or expression level of protective enzymes in the leaves. The materials with various heat-tolerance might differ in the mechanism of response to heat stress with BR application.

Gibberellins,brassinolide,and ethylene signaling were involved in flower differentiation and development in Nelumbo nucifera

Hormones play important roles in vegetative and reproductive processes;however,the regulatory roles of hormones in Nelumbo nucifera(Lotus)growth and development are unclear.In this study,nine types of endogenous hormones,including gibberellins(GA_1,GA_3,and GA_4),indole-3-acetic acid(IAA),brassinolide(BR),ethylene(ETH),jasmonic acid(JA),abscisic acid(ABA),and zeatin(ZT)were detected in dormant shoot tips,vegetative shoot tips,developing leaf buds,and developing flower buds of lotus.The results indicated that GA,ETH,and BR signaling can promote vegetative and reproductive development of lotus.GA signaling regulates plant height and stimulates flower bud differentiation.GA levels were the highest in the flower buds;exogenous GA3+4 increased plant height by approximately 90%,increased flower quantity by nearly 40%,and advanced flowering by 4 d.Suppressing GA biosynthesis using paclobutrazol decreased plant height and flower quantity by 38%and 87.1%,respectively,and delayed flowering by 15.6 d.ETH signaling has positive regulatory effects on vegetative growth and flower development.The ETH concentration in the developing leaf buds was at least 50%higher than that in other samples.Ethephon spraying led to remarkable increases in plant height and leaf thickness and extended the flowering duration.BR signaling acts as a growth promoter during vegetative and reproductive development in lotus.The highest BR levels were detected in the vegetative shoot tips.External application of28-epihomobrassinolide resulted in growth-promoting phenotypes including longer scapes,thicker leaves,and prolonged flowering.

Effects of Natural Brassinolide on Seed Germination and Hypocotyl Elongation of Beans

Seeds of soybeans and mung beans were soaked into five different concentrations （0, 0.05, 0.10, 0.20, 0.30 mg/L） of natural brassinolide （ NBR ） solution. According to the results, natural brassinolide treatment could improve seed germination rate and hypocotyl-radicle ratio of soybeans and mung beans and promote the growth of sprouts. To be specific, seed germination rate of soybeans reached the highest in 0.05 mg/L natural brassinolide treatment, which was im- proved by 25.0 percentage points compared with the control group, and the sprout length was improved by 4.33 em; 0.30 mg/L natural brassinolide exhibited the most significant promotion effect on seed germination and sprout growth of mung beans, seed germination rate was improved by 18.3 percentage points and sprout length was improved by 7.29 cm; hypocotyl-radiele ratio of soybean and mung bean sprouts reached the highest （2.96, 1.43 ） in 0.05 mg/L natural brassinolide treatment.

Foliar Application of Brassinolide Induced Regulation of Grain Yield and Quality,Antioxidant Responses and Aroma in Fragrant Rice

Brassinolide(BR)is a new green plant growth regulator.The present field study was conducted on two fragrant rice cultivars(i.e.,Meixiangzhan-2 and Xiangyaxiangzhan)to study the effects of foliar application of BR on fragrant rice performance.At the heading stage,BR solutions at 0.05,0.15,0.25 and 0.50 mg L-1 were sprayed on fragrant rice at 600 liters per hectare;these treatments were named as BR1,BR2,BR3 and BR4,respectively.The treatment sprayed with distilled water was taken as a control(CK).Compared with CK,the BR2 treatment significantly enhanced the chlorophyll concentration and net photosynthetic rate for Meixiangzhan-2,and Xiangyaxiangzhan.The BR3 and BR4 treatments increased the concentrations of chlorophyll a,chlorophyll b and carotenoid,and also enhanced net photosynthetic rate by 31.91%and 40.43%,respectively.Higher grain yields were recorded in the BR2 treatment than on CK on Meixiangzhan-2,while on Xiangyaxiangzhan,the BR3 and BR4 treatments increased grain yield compared with CK.In relation to CK,higher head rice rates were recorded in the BR2 treatment for Meixiangzhan-2,and in the BR3 and BR4 treatments for Xiangyaxiangzhan.BR treatments(BR2 for Meixiangzhan-2,BR3 and BR4 for Xiangyaxiangzhan)also significantly enhanced the activities of GPX,SOD and CAT by 10.22%to 23.00%,and reduced the malonaldehyde concentration.In addition,we observed that some BR treatments(BR2 for Meixiangzhan-2,BR3 and BR4 for Xiangyaxiangzhan)decreased the grain 2-acetyl-1-pyrroline concentration of fragrant rice.

Effect of Natural Brassinolide on Germination of Ailanthus altissima Seeds

The germination capacity of Ailanthus altissima seeds improved after the seeds were soaked with different concentrations of natural brassinolide （NBR）. The germination rate and germination energy of the seeds increased by 17.6% and 18.8%, and the mean germination speed （i.e., germination time） of the seeds was shortened by 1.4 d under the optimal concentration （0.4 mg·L^-1） treatment, compared with the control. After hypocotyls of A.altissima were treated with NBR, the elongation of the hypocotyls increased. Among different concentrations of the NBR, 0.4 mg·L^-1 NBR appeared to be the optimal concentration for the elongation of A.altissima hypocotyls.

STUDIES ON STEROIDAL PLANT GROWTH REGULATOR 24. STEREOCONTROLLED CONSTRUCTION OF THE SIDE CHAIN OF BRASSINOLIDE AND HOMOBRASSINOLIDE VIA A TANDEM VICINAL DIALKYLATION OF PYRANONE MOIETY

A stereocontrolled construction of the side chain of brassinclide and homobrassinolide has been achieved via the tandem vicinal dialkylation of the pyranone moiety as a key step.

STUDY ON THE SYNTHESIS OF BRASSINOLIDE AND RELATED COMPOUNDS 15.FORMAL SYNTHESIS OF BRASSINOLIDE VIA STEREOSELECTIVE SULFENATE-SULFOXIDE TRANSFORMATION

A formal synthesis of the natural growth promoting steroid brassinolide is described,which involves construction of side chain by 1,3-sulfoxide-hydroxyl transposition with methylation from(24S)- 22-E-24-sulfoxide 6 and(24R)-22-E-24-sulfoxide 9,respectively to (22S)-23-E-24-methyl compound 4.

Studies on the Model Synthesis of the Brassinolide and Dolicholide Side Chains

A stereoselective synthesis of brassinolide and dolicholide, which involves construction of the side chain enantiomers by a highly stereoselective aldol reaction of aldehyde 5 with the anion of α-silyloxy ketone 6 is described.

Effect and Its Mechanism of Brassinolide-regulated Starch Metabolism in Rice Germination

The study was aimed to explore the effect and mechanism of brassinolide（ BL） regulated starch metabolism in rice endosperm during seed germination.The radicle elongation of rice seeds treated with 1 μmol/L BL was inhibited during germination. The analysis on rice seeds with a GUS-fused promoter showed that BL had different regulatory effects on Wx,SBEI,and AGPS1. The effect of BL treatment on the physicochemical properties of rice starch was further investigated by scanning electron microscopy,Fourier transform infrared spectroscopy,and X-ray diffraction. The results showed that the starch treated with BL maintained better crystallinity and orderly structure,indicating that during the germination process,the degradation of starch in endosperm was slow,which might be one of the reasons for the slow radicle growth in the early stages of seed germination. This study provided important clues for further analysis of the molecular mechanisms underlying BR-regulated rice seed germination.

Brassinolide类物质的合成

对Brassinolide类物质的合成进行了概述 ,并对其构效关系进行了对比以及简单介绍了其在农业生产上的运用。

Plant Phosphatidylcholine-Hydrolyzing Phospholipases C NPC3 and NPC4 with Roles in Root Development and Brassinolide Signaling in Arabidopsis thaliana

Phosphatidylcholine-hydrolyzing phospholipase C （PC-PLC） catalyzes the hydrolysis of phosphatidylcholine （PC） to generate phosphocholine and diacylglycerol （DAG）. PC-PLC has a long tradition in animal signal transduction to generate DAG as a second messenger besides the classical phosphatidylinositol splitting phospholipase C （PI-PLC）. Based on amino acid sequence similarity to bacterial PC-PLC, six putative PC-PLC genes （NPC1 to NPC6） were identified in the Arabidopsis genome. RT-PCR analysis revealed overlapping expression pattern of NPC genes in root, stem, leaf, flower, and silique. In auxin-treated PNPc3：GUS and PNPc4：GUS seedlings, strong increase of GUS activity was visible in roots, leaves, and shoots and, to a weaker extent, in brassinolide-treated （BL） seedlings. PNPc4：GUS seedlings also responded to cytokinin with increased GUS activity in young leaves. Compared to wild-type, T-DNA insertional knockouts npc3 and npc4 showed shorter primary roots and lower lateral root density at low BL concentrations but increased lateral root densities in response to exogenous 0.05-1.0 I^M BL BL-induced expression of TCH4 and LRX2, which are involved in cell expansion, was impaired but not impaired in repression of CPD, a BL biosynthesis gene, in BL-treated npc3 and npc4. These observations suggest NPC3 and NPC4 are important in BL-mediated signaling in root growth. When treated with 0.1 I^M BL, DAG accumulation was observed in tobacco BY-2 cell cultures labeled with fluorescent PC as early as 15 min after application. We hypothesize that at least one PC-PLC is a plant signaling enzyme in BL signal transduction and, as shown earlier, in elicitor signal transduction.

Studies on the Model Synthesis of the Brassinolide and Dolicholide's Side Chains

A highly stereoselective synthesis of the side chain enantiomers of brassinolide and dolicholide through an aldol reaction of 2-(4-methoxy benzyloxyl) propionylaldehyde (5) with the anion of 1-(tert-butyldimethylsiloxy)-3-methyl-2-butanone (6) is described.

油菜素内酯对美味侧耳菌丝体生长发育及子实体产量和质量的影响

利用美味侧耳(Pleurotus sapidus (Schulv) Sacc.)为试材,通过向培养基中添加不同浓度的油菜素内酯(Brassinolide,简称BR),以及出菇期用不同浓度的BR水溶液喷洒处理,研究了对美味侧耳菌丝体生长速度,原基分化及子实体产量和表观质量的影响。试验结果表明,较低浓度(10^(-4)ppm)的BR具有刺激菌丝体生长的作用,而较高浓度(10^(-1)ppm和10^(-2)ppm)的BR具有刺激子实体原基分化的作用。在试验所用的浓度(10^(-1)ppm和10^(-3)ppm)范围内,BR对于实体产量和表观质量无显著影响。

芸苔素内酯

中文通用名称：芸苔素内酯英文通用名称：brassinolide理化性质：芸苔素内酯为甾醇类植物激素，纯品外观为白色结晶体，熔点：256-258℃，水中溶解度为5rag／kg，溶于甲醇、乙醇、氯仿、丙酮和四氢呋喃等多种有机溶剂，属低毒植物生长调节剂，对人畜毒性较低，无人体中毒报道。

芸苔素内酯

芸苔素内酯，英文通用名brassinolide，中文别名：益丰素、天丰素、油菜素内酯、农梨利；曾用商品名：硕丰481，芸薹素内酯，云大120，皇嘉芸薹素等。化学名：2a，3a，22s，23s．四羟基-24R-乙基-B-高-7-氧杂-5a-胆甾-6-酮。农药类别：植物生长调节剂化学类别：激素类。芸苔素内酯外观为白色结晶粉末，易溶于甲醇、乙醇、氯仿、丙酮等，pH值5．4；对人畜低毒。

Regulation of Brassinosteroid Biosynthesis and Inactivation

Brassinosteroids （BRs） are a group of naturally-occurring steroidal phytohormones playing fundamental roles during normal plant growth and development. Using a combination of experimental approaches, including analytical chemistry, genetics, and biochemistry, the major BR biosynthetic pathway has been largely elucidated. The least-understood knowledge in the BR research field is probably the molecular mechanisms controlling the bioactive levels of BRs in response to various developmental and environmental cues. In this review, we focus our discussion on a recently-proposed, 8-step predominant BR biosynthetic pathway, several newly-identified transcription factors regulating the expression of key enzymes that catalyze BR biosynthesis, and up-to-date information about the mechanisms that plants use to inactivate unnecessary BRs.

Somatic Embryogenesis Receptor Kinases Control Root Development Mainly via Brassinosteroid-Independent Actions in Arabidopsis thaliana

Brassinosteroids （BRs）, a group of plant steroidal hormones, play critical roles in many aspects of plant growth and development. Previous studies showed that BRI1-mediated BR signaling regulates cell division and differentiation during Arabidopsis root development via interplaying with auxin and other phytohormones. Arabidopsis somatic embryogenesis receptor-like kinases （SERKs）, as co-receptors of BRI1, were found to play a fundamental role in an early activation step of BR signaling pathway. Here we report a novel function of SERKs in regulating Arabidopsis root development. Genetic analyses indicated that SERKs control root growth mainly via a BR-independent pathway. Although BR signaling pathway is completely disrupted in the serkl bakl bkkl triple mutant, the root growth of the triple mutant is much severely damaged than the BR deficiency or signaling null mutants. More detailed analyses indicated that the triple mutant exhibited drastically reduced expression of a number of genes critical to polar auxin transport, cell cycle, endodermis development and root meristem differentiation, which were not observed in null BR biosynthesis mutant cpd and null BR signaling mutant bril-701.