Differential biosynthesis and accumulation of picrosides in an endangered medicinal herb Picrorhiza kurroa

Picrorhiza kurroa Royle ex Benth (Family: Scrophulariaceae) is a medicinal herb, mainly found in the North-Western Himalayas. Extensive harvesting for pharmaceutical purposes, lack of organized cultivation and unorganized methods of uprooting the plants because of unawareness has brought an endangered status to this important herb in nature. The medicinal property of this plant is attributed to monoterpenoid picrosides. The influence of developmental status of different growth stages on picrosides content is poorly understood in Picrorhiza kurroa. Picroside-I (P-I) content increased from 0.05 % to 0.76 % in different growth stages of shoots. Significant increase in the contents of P-I (0.15–0.50 %) and Picroside-II (P-II) (0.1–0.45 %) was observed in rhizomes of different developmental stages. Highest amounts of P-I (8.7 %) and P-II (5.3 %) was detected in uppermost part of mature dried rhizomes compared to bottom part with 2.9 % and 2.2 % of P-I and P-II, respectively. P. kurroa grown at high altitude (Sairopa, 4,500 amsl) showed 1.75-folds increase in P-I in leaves whereas exponential increase in the P-I content was detected (0.05–1.7 %) in the leaves of different developmental stages (L1-L5) of P. kurroa grown at lower altitude (Jagatsukh, 1,900 m). Variable amounts of P-I and P-II in different growth and developmental stages of P. kurroa imply importance of selection of plant material (rhizomes and roots). The study undertaken explored the status of metabolites accumulation and biosynthesis in the field grown plants of P. kurroa where not only environmental parameters but different morphogenetic stages of its developmental cycles, different age groups and different parts of plantlets were extensively analysed and estimated for medicinally important picrosides.     

ABC transporters mined through comparative transcriptomics associate with organ-specific accumulation of picrosides in a medicinal herb,Picrorhiza kurroa

Protoplasma - Picrorhiza kurroa Royle ex Benth is a valuable medicinal herb of North-Western Himalayas due to presence of two major bioactive compounds, picroside-I and picroside-II used in the...     

Potential of thidiazuron in improved micropropagation of Picrorhiza kurroa– an endangered medicinal herb of alpine Himalaya

The potential of thidiazuron (1-phenyl-3-(1, 2, 3-thiadiazol-5-yl) urea (TDZ) in the micropropagation of Picrorhiza kurroa, a western Himalayan herb was studied. The roots and rhizomes of this plant are rich in medicinally important glycosides i.e., picroside I, picroside II and kutkoside. Nodal segments (2.0–2.5 cm) from plants were pretreated with 0, 0.25, 0.50, 0.75, 1.0 μM TDZ for 7, 15 and 30 days. Maximum shoot multiplication was recorded after 60 days, provided, the nodal segments pretreated with 0.5 μM TDZ for 15 days were transferred to 0.8% agar gelled MS medium containing 3.0% sucrose. The shoots also showed profuse rooting having maximum length. When these plantlets were incubated at 15°C for 10 days and transferred to sand under polyhouse conditions, 100% survival was recorded after one month. In contrast, when the plantlets were not incubated at 15°C, only 86% survival was recorded. While the stomata and chlorophyll content of the tissue culture-raised plantlets treated at 15°C were comparable to that of plants growing in the field, the ones that were not treated at 15°C showed lower number of stomata and chlorophyll content.     

巴西橡胶树胶乳和悬浮细胞中MVA和MEP代谢途径基因的表达分析

MVA和MEP代谢途径是植物类异戊二烯代谢途径的两条重要次生代谢途径。该研究利用荧光定量PCR技术,分析了橡胶树胶乳和橡胶树花药愈伤组织来源的悬浮细胞中MVA代谢途径和MEP代谢途径中关键基因的表达水平,同时分析了茉莉酸的结构类似物冠菌素(coronatine,COR)对悬浮细胞中Hb AACT3,Hb HMGR4,Hb HMGR5,Hb DXS2,Hb DXR和Hb SQS1基因表达的调节作用。结果表明:在MVA代谢途径中,基因Hb AACT1,Hb AACT2,Hb HMGS1,Hb HMGS2,Hb HMGR1,Hb HMGR3,Hb MVK,Hb PMK,Hb MVD1,Hb MVD2和IPP下游代谢基因Hb IPPI1和Hb FDPS1在胶乳中的表达量要相对高于其在悬浮细胞中的表达量,然而橡胶树悬浮细胞中MEP代谢途径基因Hb DXS1,Hb DXS2,Hb DXR,Hb CMS1,Hb CMS2,Hb CMK,Hb MCS1,Hb MCS2,Hb HDS,Hb HDR和鲨烯合酶基因Hb SQS1的表达水平要相对高于胶乳。而且COR能不同程度地上调Hb HMGR5,Hb HMGR4,Hb SQS1,Hb DXS2和Hb DXR基因的表达水平。该研究结果为探索利用橡胶树悬浮细胞体系研究次生代谢合成调控以及生产活性次生代谢产物奠定了基础。     

Habitat distribution modeling of endangered medicinal plant Picrorhiza kurroa (Royle ex Benth) under climate change scenarios in Uttarakhand Himalaya,India

Climate change has been the key factor in changing the alpine vegetation's habitat and causing it to migrate to higher latitudes. The present study aims to model the current and future potential habitat distribution of endangered medicinal plant Picrorhiza kurroa Royle ex Benth in Uttarakhand Himalaya using the maximum entropy (MaxEnt) modeling. We initially select twenty-two environmental variables (bioclimatic + topographic) got from the Fifty-four (54) species occurrence points, which were further reduced to nine variables to prevent multicollinearity. Shared Socioeconomic Pathways (SSP1–2.6 and SSP2–4.5) from the CMIP6 (BCC-CSM2-MR) climate model for the periods 2041–60 and 2061–80 were used to predict the current and future habitat distribution of P. kurroa. Results showed that the precipitation of the driest month (Bio 14; 33.8%), isothermality (Bio 3; 20.2%), mean temperature of warmest quarter (Bio 10; 12.7%), and temperature annual range (Bio 7; 12.2%) were the important bioclimatic variables influencing the habitat of P. kurroa. Overall, there is a decrease in the habitat of P. kurroa under climate change scenarios. The present results may prove insightful for the decision-makers to identify suitable sites in the wild for the further propagation of P. kurroa.     

Quantitative role of different embryonic tissues in mevalonate metabolism by sterol and nonsterol pathways. Relationship with enzyme activities of cholesterogenesis

3-Hydroxy-3-methylglutaryl-CoA reductase, mevalonate kinase, mevalonate-5-phosphate kinase and mevalonate-5-pyrophosphate decarboxylase activities have been determined in brain, liver, intestine and kidneys from 19-day-old chick embryo. Levels of brain reductase and decarboxylase were clearly higher than those found in the other tissues assayed. However, only small differences were observed in the activity of both kinases among the different tissues. Mevalonate metabolism by sterol and nonsterol pathways has been investigated in chick embryo at the same developmental stage. Mevalonate incorporation into total nonsaponifiable lipids was maximal in liver, followed by intestine, brain and kidneys. The shunt pathway of mevalonate not leading to sterols was negligible in both brain and liver, while a clear CO2 production was observed in intestine and kidneys. Sterols running in TLC as lanosterol and cholesterol were the major sterols formed from mevalonate by brain and kidney slices, while squalene and squalene oxide(s) were found to be mainly synthesized by liver slices. Minor differences in the percentage of different sterols were observed in chick embryo intestine. The importance of free and esterified cholesterol accumulation in the different tissues on the inhibition of cholesterogenic activity is discussed.     

Role of mucilage during achene germination and sprout growth of the endangered Tibetan medicinal herb Mirabilis himalaica (Nyctaginaceae) exposed to abiotic stresses

Aim Mirabilis himalaica (Nyctaginaceae) is an endangered medicinal plant mainly distributed in the plateau region of northern Tibet, China. The outer surface of M. himalaica achenes is covered by a pectinaceous mucilaginous layer upon hydration. However, the role of the achene mucilage is poorly understood. In this study, we investigated the effects of mucilage on achene germination and sprout growth under abiotic stress to explain how M. himalaica survive the alpine environment.Methods We investigated the effect of mucilage on achenes germination by contrast the capacity of water absorption, dehydration and respiration of intact achene and the achene with mucilage removal. We performed abiotic stresses experiments including drought stress, salt stress, cold stress and high temperature stress, and quantified the effects of mucilage removal on achene germination rate, root and shoot lengths of seedlings.Important findings Mucilage is extremely hydrophilic, and the mass of intact achenes can be 9-fold greater than that of demucilaged achenes. The removal of the mucilaginous layer did not significantly change final germination percentages under ideal conditions, but intact achenes (i.e. with mucilage) took longer to germinate. The mucilage significantly decreased seed respiration rates by acting as a physical barrier that prevented oxygen diffusion. Germination rates, shoot and root growth of intact achenes were higher than those of demucilaged ones during exposures to cold, heat, osmotic and salt stresses. Achene mucilage presumably plays an ecologically important role in the life cycle of M. himalaica by aiding the critical achene germination and early seedling growth in the stressful habitats of the plateau region of northern Tibet.     

Expression pattern of CYC-like genes relating to a dorsalized actinomorphic flower in Tengia (Gesneriaceae)

Tengia has been called a "natural peloria" in the family Gesneriaceae because it exhibits an almost perfect actinomorphic flower from whorl one to whorl three. It would be especially interesting to know whether or how CYC-like gene activities are related to this type of perfect actinomorphic flower. To address this, we have isolated four CYC-like TCP genes and carried out an investigation on their expression patterns in Tengia. TsCYC1C and TsCYC1D have similar expression patterns with strong signals being detected in all five petals and stamens, whereas TsCYC2A and TsCYC2B are only transiently expressed in the very early floral meristem. Our results suggest that the expansion of the expressions of TsCYC1C and TsCYC1D from the dorsal to the ventral petals is likely responsible for the evolutionary formation of the fully dorsalized actinomorphic corolla, that is, an expanded functional domain of CYC-like gene dorsal identity in Tengia corolla. However, the expressions of TsCYC1C and TsCYC1D are not correlated with stamen abortion; therefore, TsCYC genes do not functionally repress the stamen development in Tengia flowers. This is probably due to changed cis-activities that result in the cell cycle-related genes uncoupling from the TsCYC regulatory pathway in Tengia.     

Expression pattern of CYC‐like genes relating to a dorsalized actinomorphic flower in Tengia (Gesneriaceae)

Abstract Tengia has been called a “natural peloria” in the family Gesneriaceae because it exhibits an almost perfect actinomorphic flower from whorl one to whorl three. It would be especially interesting to know whether or how CYC‐like gene activities are related to this type of perfect actinomorphic flower. To address this, we have isolated four CYC‐like TCP genes and carried out an investigation on their expression patterns in Tengia. TsCYC1C and TsCYC1D have similar expression patterns with strong signals being detected in all five petals and stamens, whereas TsCYC2A and TsCYC2B are only transiently expressed in the very early floral meristem. Our results suggest that the expansion of the expressions of TsCYC1C and TsCYC1D from the dorsal to the ventral petals is likely responsible for the evolutionary formation of the fully dorsalized actinomorphic corolla, that is, an expanded functional domain of CYC‐like gene dorsal identity in Tengia corolla. However, the expressions of TsCYC1C and TsCYC1D are not correlated with stamen abortion; therefore, TsCYC genes do not functionally repress the stamen development in Tengia flowers. This is probably due to changed cis‐activities that result in the cell cycle‐related genes uncoupling from the TsCYC regulatory pathway in Tengia.     

Expression of receptors for melanin-concentrating hormone (MCH) in different tissues and cell lines

Melanin-concentrating hormone (MCH) is a potent orexigenic neuropeptide and a physiological antagonist of alpha-melanocyte-stimulating hormone (alpha-MSH) in the brain as well as at peripheral sites, including the pigmentary systems of specific vertebrates. Two receptor subtypes for MCH, MCH-R1 and MCH-R2, have been cloned, but other receptor subtypes are likely to exist. Based on our own data and the current literature, we have compared the expression of different receptors for MCH in various mammalian cell lines and tissues. Summarizing all data currently available, we conclude that the two cloned MCH receptors, MCH-R1 and MCH-R2, exhibit differences in their expression pattern, although MCH-R1 is generally colocalized in all tissues where MCH-R2 expression is found. It appears that MCH-R1 is more abundant and has a wider distribution pattern than MCH-R2. Other hypothetical MCH-R subtypes may be expressed in specific tissues, e.g., in the pigment cell system.     

鲤鱼肌肉生长抑制素基因(MSTN)的克隆及其组织表达特征

肌肉生长抑制素(Myostatin,MSTN)是动物肌肉发育和生长过程中的负调控因子,对MSTN的研究将有助于促进动物生产。鲤鱼是我国的主要淡水养殖对象之一。因此,我们采用RT-PCR方法克隆了鲤鱼MSTN cDNA(No.EF551058)的部分序列,长度为921bp,编码306个氨基酸残基。鲤鱼MSTN具有MSTN的共同特征,有蛋白酶水解位点RIRR和9个保守的半胱氨酸残基。多重序列比较发现其与斑马鱼GDF8有极近的亲缘关系,96.7%的氨基酸序列同源。不同组织的RT-PCR分析发现鲤鱼MSTN主要在肌肉和脑部表达,而其他所检测组织未见表达。鲤鱼MSTN不仅在肌肉生长发育中发挥作用,可能在神经系统发育中也有其作用。