Effect of applications of 1-MCP and ethylene on the ripening and degreening process of banana fruits cv. Barranquillo

The banana cv. Barranquillo (Musa acuminata, AAA, 'Gros Michel') is a highly desired fruit because of its productive potential and organoleptic quality but various aspects of the ripening process are unknown. The objective of this research was to evaluate the effect of applications of 1-MCP and ethylene on the ripening and degreening process. Two experiments were carried out at room temperature with fruits harvested at commercial maturity. The first four treatments evaluated maturation: control, ethylene, 1-MCP, and 1-MCP + ethylene. In the second experiment, different concentrations of ethylene based on ethephon (0, 100, 500 and 1000 µL L-1) were evaluated. The fruits treated with 1-MCP decreased the ripening process, and 1-MCP was a good alternative for conserving the fruits; the ethylene had opposite results. The color index of the skin, weight loss, firmness, total soluble solids, and maturity ratio had changes associated with the presence of ethylene. In the second experiment, the ethylene applications between 100 and 500 µL L-1 sufficiently stimulated degreening but accelerated the ripening process.

El banano cv. Barranquillo (Musa acuminata, AAA, 'Gros Michel') es un fruto muy apetecido por su potencial productivo y calidad organoléptica, pero se desconocen varios aspectos del proceso de maduración. El objetivo de esta investigación fue evaluar el efecto de la aplicación de 1-MCP y etileno en la maduración y en el proceso de desverdizado. Se realizaron dos experimentos a temperatura ambiente y con frutos cosechados en madurez comercial; en el primero, se evaluaron cuatro tratamientos, para entender la regulación de la maduración, estos fueron: testigo, etileno, 1-MCP y 1-MCP+etileno. En el segundo experimento, se evaluaron diferentes concentraciones de etileno, a base de etefon (0, 100, 500 y 1000 µL L-1). Los frutos tratados con 1- MCP presentaron una disminución en el proceso de maduración, por tanto, el 1-MCP, se convierte en una buena alternativa de conservación, mientras que con etileno, el proceso fue opuesto. Se evidenció que el índice de color de la epidermis, la pérdida de peso, la firmeza, los sólidos solubles totales y la relación de madurez se consideran cambios asociados a la presencia de etileno. En el segundo experimento se encontró que, aplicaciones de etileno entre 100 y 500µL L-1, se consideran suficientes para estimular el desverdizado, pero aceleran el proceso de maduración.

ROPs: Molecular Switches of Multiple Signal Pathways in Plant Cells / 中国生物化学与分子生物学报

RHO-related GTPases of plants (ROPs) are a class of signal transduction G proteins (alsoknown as GTP binding proteins) widely existing in plants. ROP proteins act as " molecular switches" toregulate the signal transduction process during cellular activities such as plant cell polarity regulation, plant morphological development, hormone level regulation, stress responses and many other life activitiesby shifting between inactive GDP-binding and active GTP-binding forms in the cells. In this review, thedomain structure, classification, the mechanism of activity regulation and biological functions of ROPproteins were summarize. Furthermore, ROP proteins from Arabidopsis, maize, rice and barley werephylogenetically analyzed. The results show that ROP proteins were classified into two types based on thedomain structure of the proteins. However, these ROP proteins were divided into 4 clades based on thesimilarity of protein sequences. Furthermore, the mechanism of ROP proteins as a molecular switchregulating various signaling pathways in cells, and the specific functions and mechanisms of ROPs in thepolarized growth of pollen tubes, root hairs and plant pavement cells and other stress responses werecharacterized. In addition, the research progress of the function of ROPs in plant hormones such as ABA, IAA and BR mediated signal transduction were described as well. At last, the unanswered questions suchas why different ROP proteins play distinct roles in the same signaling pathway and how ROPs coordinatedifferent signal pathways to jointly regulate a plant’ s development or physiological process werediscussed, which may shed light on future research.

Application Progress of Plant Growth Regulator in Production of Chinese Medicinal Materials / 中国实验方剂学杂志

Plant growth regulator （PGR） is mostly a class of chemical synthesis substance with physiological activities similar to plant hormones，which can promote cell elongation，induce vascular differentiation or accelerate tissue aging via regulating the physiological processes such as photosynthesis，respiration，transpiration，signal transduction，substance absorption and operation. PGR has the advantages of small dosage，high efficiency，low toxicity and less residue，and it is widely used in the planting of Chinese medicinal herbs. By consulting the relevant literature published in recent years，this paper briefly summarizes the main types of PGR，e.g.auxins，gibberellins，cytokinins，abscisic acid and ethylene，etc. On the other hand，this article analyzes and sums up the specific applications of PGR in the manufacture of Chinese herbal medicine，for instance，promoting seed germination，improving seed setting rate or fruit setting rate，dwarfing plants，inhibiting reproductive growth，regulating gender differentiation，stimulating fruit falling，enhancing resistance and so on. The problems existing in the practical use of PGR are pointed out，non-differentiation of specific species，unreasonable combination，not paying attention to the operation method，arbitrarily increasing the dose，lack of residue limit standard and reducing the content of some effective components，for example.Meanwhile，some feasible suggestions are put forward.Not only the suitable types of PGR should be selected in a reasonable and standardized manner，but also the appropriate concentration，dosage and period of application should be chosen carefully； the dual effects of PGR on plant growth and active ingredients in medicinal organs should be concerned，so as to improve the yield and avoid the loss of effective components on the basis of ensuring the quality of Chinese medicinal materials； it is necessary to strengthen the registration of PGR in the production of Chinese medicinal materials and establish residue limit standards to provide a monitoring basis for ensuring the safety of Chinese medicine in the future.The scientific use of PGR can promote the increase of agricultural yield and farmers' income，and make the healthy development of Chinese herbal medicine planting industry.

New Assay Method for Allene Oxide Cyclase, an Important Enzyme in Jasmonic Acid Biosynthesis.

Aims: Allene oxide cyclase (AOC) (EC 5.3.99.6) is an important enzyme of jasmonates (JAs) biosynthesis. JAs are important signals that play a pivotal role in defense response of plants to environmental cues. Regulation JA biosynthesis is believed useful for elucidating the mechanism of plant defense system. Despite the high potential of AOC as a target for JA biosynthesis inhibitors, an efficient assay method suitable for screening AOC inhibitors is still not available. The aim of this work is to develop an efficient AOC assay method. Study Design: Using excess amount of purified recombinant allene oxide synthase (AOS) combined with 13(S)-hydroperxy-9(Z), 11(E), 15(Z)-octadecatrienoic acid (13-HPOT), we established an efficient method to generate (12,13S)-epoxyoctadecatrienoic acid (EOT), the substrate of AOC. The AOS produced EOT was subsequently converted to (9S,13S)-12-oxo- (10,15Z)-phytodienoic acid (OPDA) by using purified recombinant AOC in a real time manner and the amount of OPDA was determined by HPLC. Place and Duration of Study: All the experiments were conducted from October 2009 to March 2013 at Akita Prefectural University, Japan. Methodology: The recombinant AOS and AOC were expressed in E. coli. The target proteins were purified using affinity chromatography, respectively. The unstable EOT was generated by using excess AOS combined with 13(S)-hydroperxy-9(Z), 11(E), 15(Z)-octadecatrienoic acid. The AOC synthesized OPDA was characterized by the comparison of HPLC retention time with the OPDA standard. AOC activity was calculated by determine the amount of OPDA in the assay system. Results: We found in the presence of 50 nmol of purified AOS together with 20 M 13-HPOT, the synthesis of OPDA was saturated when using 5 nmol of purified AOC in the enzyme reaction for 30 min. Our results indicated that the AOC activity can be determined by dual enzyme system. Conclusion: We established an efficient assay method for AOC which may be applied for screening of AOC inhibitors.

The morphology and bioactivity of the rice field cyanobacterium Leptolyngbya / Morfología y bioactividad de la cianobacteria Leptolyngbya en los campos de cultivo de arroz

The genus Leptolyngbya comprises filamentous cyanobacteria that are important in rice fields. In the rhizosphere, cyanobacteria produce a variety of secondary metabolites such as auxins that are important in agriculture soil performance. To assess this, Leptolyngbya strain MMG-1, was isolated from the rhizosphere of rice plants and described. For this, the morphology of this strain was studied by light microscopy as well as by confocal laser scanning microscopy. Besides, the ability of this strain to synthesize an auxin-like bioactive compound was demonstrated under various culture conditions (different amounts of tryptophan; pH; different alternating light:dark periods; duration of the incubation). The auxin-like compound was extracted from the culture of Leptolyngbya strain MMG-1 and identified as indole-3-acetic acid (IAA) by thin layer chromatography (TLC) as well as by high performance liquid chromatography (HPLC). Our results showed that the strain required the precursor L-tryptophan for the synthesis of IAA. Leptolyngbya strain MMG-1 accumulated IAA intracellularly. The IAA secreted by Leptolyngbya strain MMG-1 was significantly correlated with the initial concentration of L-tryptophan in the medium, as well as with the duration of the incubation. The bioactivity of the secreted IAA was determined by its effect on the rooting pattern of Pisum sativum seedlings. The culture supernatant of Leptolyngbya strain MMG-1 stimulated the seedling lateral rooting, while it decreased root length. Hence, rhizospheric Leptolyngbya produced auxin under different conditions and affected the plants rooting pattern. Rev. Biol. Trop. 62 (3): 1251-1260. Epub 2014 September 01.

El género Leptolyngbya comprende cianobacterias filamentosas que son importantes en los campos de cultivo de arroz. En la rizosfera, las cianobacterias producen una variedad de metabolitos secundarios, tales como auxinas, que son importantes en el rendimiento de la agricultura del suelo. La cepa Leptolyngbya MMG-1, fue aislada de la rizosfera de plantas de arroz y se describe en este trabajo. La morfología de esta cepa se estudió por microscopía de luz, así como por microscopía confocal de barrido láser. Además, se estimó la capacidad de esta cepa para sintetizar el compuesto bioactivo auxina como se demostró en diversas condiciones de cultivo (diferentes cantidades de triptófano; pH; diferente luz alterna: períodos oscuros; duración de la incubación). La auxina se extrajo a partir del cultivo de la cepa Leptolyngbya MMG-1 y se identificó como ácido indol-3-acético (AA) por cromatografía de capa fina (TLC), así como por cromatografía líquida de alta resolución (HPLC). Nuestros resultados mostraron que la cepa requiere el precursor de L-triptófano para la síntesis de IAA. La cepa Leptolyngbya MMG-1 acumula intracelularmente IAA. El IAA secretada por la cepa Leptolyngbya MMG-1 se correlacionó significativamente con la concentración inicial de L-triptófano en el medio, así como con la duración de la incubación. La bioactividad de la IAA secretada se determinó por su efecto sobre el patrón de enraizamiento de plantas de semillero de Pisum sativum. El sobrenadante del cultivo de la cepa Leptolyngbya MMG-1 estimuló el enraizamiento lateral en la plántula, mientras que se redujo la longitud de la raíz. Por lo tanto, la producción de auxina por Leptolyngbya rizosférica afectó el crecimiento de las plantas.

Seed germination and young seedling propagation of Anoectochilus roxburghii / 中国药学杂志

OBJECTIVE: To study the effect of different media on seed germination and young seedling propagation of Anoectochilus roxburghii. METHODS: A. roxburghii seeds were cultured in 6 basal media for 12 weeks, and germination rates were calculated; orthogonal design was used to study the effects of NAA and 6-BA on the propagation of young seedlings of A. roxburghii. After 4 months, the leaf number, stem internode number, root number, the length of root, plant height, and fresh mass were measured respectively. RESULTS: The effects of different media on seed germination and protocorm differentiation of A. roxburghii were different. Germination rate was the highest on MS medium, which was 60.38%, and protocorm differentiation was optimal on half-strength MS medium. Different combinations of NAA and 6-BA didn't show significant difference on the growth of young seedlings of A. roxburghii, and the appropriate medium was 1/2MS + NAA 1.0 g · L-1 + 6-BA 2.0 mg · L-1. CONCLUSION: The optimization of culture medium can stimulate seed germination and young seedling propagation of A. roxburghii. Copyright 2012 by the Chinese Pharmaceutical Association.

Establishment of tissue culture and rapid propagation system of Typhonium flagelliforme / 中草药

Objective: To establish the rapid propagation system and tissue culture techniques of Typhonium flagelliforme for large-scale seedlings. Methods: Using media with different hormones proportions, the tuber tissue was found to be a good explant for inducing asexual propagation system. Results: The callus culture medium consisted of MS+NAA 0.2 mg/L+KT 1.0 mg/L+sucrose 3%+agar 6 g/L could generate callus successfully. Medium consisted of MS+NAA 0.2 mg/L+6-BA 2 mg/L+sucrose 3% + agar 6 g/L was a superlative proportion of hormones concentration to generate adventitious buds efficiently, especially for higher proliferated multiples. The rooting medium consisted of 1/2 MS+NAA 0.2 mg/L+IB A 0.4 mg/L+KT 0.2 mg/L+sucrose 3%+agar 6 g/L+AC 0.3 g/L was conducive to generate roots rapidly. The expiants could be acclimatized after a period of 12 to 14 weeks. Experiments of one-step-seedling formation indicated that the one-step-seedling formation medium, containing MS+NAA 0.2 mg/L+6-BA 1.5 mg/L+sucrose 3%+agar 6 g/L was the best proportion of hormone concentration, for 5 to 6 weeks, new plantlets could be developed, which will be acclimatized in 10 weeks. Conclusion: The tissue culture techniques and rapid propagation system of T. flagelliforme could be used for large-scale seedlings and lay a foundation for its improved breeds.

Wheat (Triticum aestivum) peptide (s) mimic gibberellin action and regulate stomatal opening.

Wheat peptides (0.5 to 3 KDa Mr) mimick hormonal activity like that of gibberellins and forced open dark closed stomata. The deionized amphoteric peptides solution after passing through cation and anion exchanger resins was run through Amicon’s ultrafilters, 10, 3 and 0.5 kDa (Mr) cut off system. The 3 to 0.5 kDa fraction passed through sephadex LH-20 column and collected in 140 tubes (5 ml in each tube). The two fractions F 9 (91-100 tubes) and F 12 (121-130) were found much active on stomatal opening and -amylase activity, respectively and were ninhydrin positive. Capillary electrophoresis of F 9 fraction yielded several peptides ranging 1600 to 2200 (Mr) and F 12 fraction showed 1800 – 2800(Mr). Both the fractions were totally hydrolysed for amino acid analysis by HPLC. Most of the amino acids were present except cystein in both the fractions. The F 9 fraction, (peptide present in 10 μg fresh wt tissue per ml) induced the dark grown closed stomata to open upto 70%. In F 12 fraction, (peptide present in 10 μg fresh wt equivalent tissue per ml) showed -amylase induction which was much higher than GA3 (10-9 M). The peptide might be present in membrane and bound with GA that activated -amylase m-RNA synthesis. The peptide might act directly on -amylase gene.

Alterations in core histone variant ratios during maize root differentiation, callus formation and in response to plant hormone treatment

Although several histone variants have been studied in both animal and plant organisms, little is known about their distribution during processes that involve alterations in chromatin function, such as differentiation, dedifferentiation and hormone treatment. In this study we evaluated the ratio of each histone variant in each of the four core histone classes in the three developmental zones of maize (Zea mays L.) root and in callus cultures derived from them, in order to define possible alterations either during plant cell differentiation or dedifferentiation. We also evaluated core histone variant ratios in the developmental zones of roots treated with auxin and gibberellin in order to examine the effects of exogenously applied plant hormones to histone variant distribution. Finally, immunohistochemical detection was used to identify the root tissues containing modified forms of core histones and correlates them with the physiological status of the plant cells. According to the results presented in this study, histone variant ratios are altered in all the cases examined, i.e. in the developmental zones of maize root, in callus cultures derived from them and in the developmental zones of roots treated either with auxin or gibberellin. We propose that the alterations in linker histone variant ratios are correlated with plant cell differentiation and physiological status in each case.

Distribution of linker histone variants during plant cell differentiation in the developmental zones of the maize root, dedifferentiation in callus culture after auxin treatment

Although several linker histone variants have been studied in both animal and plant organisms, little is known about their distribution during processes that involve alterations in chromatin function, such as differentiation, dedifferentiation and hormone treatment. In this study, we identified linker histone variants by using specific anti-histone Hl antibodies. Each variant's ratio to total Hl in the three developmental zones of maize (Zea mays L.) root and in callus cultures derived from them was estimated in order to define possible alterations either during plant cell differentiation or during their dedifferentiation. We also evaluated linker histone variants' ratios in the developmental zones of maize roots treated with auxin in order to examine the effects of exogenous applied auxin to linker histone variant distribution. Finally, immunohistochemical detection was used to identify the root tissues containing each variant and correlate them with the physiological status of the plant cells. According to the results presented in this study, linker histone variants' ratios are altered in the developmental zones of maize root, while they are similar to the meristematic zone in samples from callus cultures and to the differentiation zone in samples from roots treated with auxin. We propose that the alterations in linker histone variants' ratios are correlated with plant cell differentiation and dedifferentiation.