Hoehnea 29(2): 151-158. 2 tab., 4 fig., 2002

Soluble carbohydrate similarities between Echinolaena inflexa and minutiflora ()

Moemy Gomes Moraes I, Amanda de SouzaI, Rosemeire Aparecida Bom Pessoni I and Rita de Cassia Leone Figueiredo-Ribeiro1,2

Received: 10 September, 2001; accepted: 28 May. 2002

ABSTRACT - (Soluble carbohydrate similarities between Echinolaena inj7exa and Melin is lIIinutijlora - Poaceae). Echinolaena inj7exa (Poir.) Chase is a native grass species with high biomass production, with abundance in the cerrado comparable to Melinis lIIinlltijlora Beauv., a forage grass of African origin, wide pread in the cerrado, displacing some native herbaceous species. In the present study, sugars from both species were analysed in two distinct periods of their annual developmental cycle. Water-soluble carbohydrates varied significantly in both species between summer and winter. Soluble carbohydrate contents were higher in winter in different tissues of both species, but sugar alcohols were higher in E. inj7exa. The presence of these sugars and other low molecular weight carbohydrates is discussed with respect to stress tolerance and the establishment of both species in the cerrado. Key words: soluble carbohydrates, cerrado, grasses, biological invasion

RESUMO - (Similaridade de carboidratos soluveis em Echinolaena inj7exa e Melinis lIIinutijlora - Poaceae). Echinolaena inj7exa (Poir.) Chase e uma gramfnea nativa, amplamente distribufda em areas de cerrado e com biomassa aerea companlvel a de Melinis minutijlora Beauv., que e uma gramfnea de origem africana, tambem largamente distribufda nessas areas, onde compete com as especies herbaceas de ocorrencia natural. No presente trabalho foram analisados os carboidratos soluveis de ambas as especies, em duas esta~6es anuais, sendo observadas varia~6es no conteudo e na composi~ao desses compostos, com tendencia a um aumento no inverno, em todos os tecidos analisados. Destacou-se 0 teoI' de a~ucares alcoois de E. inj7exa, que foi cerca de 10 vezes maior que 0 de M. min/ltijlora no inverno. A presen~a marcante de a~ucares alcoois e de outros carboidratos de baixo peso molecular nessas especies poderia estar associada atolerancia a estresses ambientais, favorecendo seu estabelecimento no cerrado. Palavras-chave: carboidratos soluveis, cerrado, gramfneas invasao biol6gica

Introduction Pivello et al. (1999a, and references therein), this factor also contributed significantly for the success of Comparative physiological and ecological studies the invasive grass Eragrostis lehmanniana (Lehmann on the invasion of neotropical savannas by African lovegrass) in the Arizona arid grassland. grasses have been calTied out in the last ten years Melinis minutiflora Beauv., an African species, (Klink & Joly 1989, Bilbao & Medina 1990, Anten et was introduced in Brazil due to its high forage value. al. 1998, Pivello et al. 1999a, b). These species invading This species has been propagating rapidly in the native areas have drastic effects on native species cerrado, perhaps because of the suitable climate and and they may contribute directly to changes in soil conditions for its growth (Filgueiras 1990). The ecosystems processes (Williams & Baruch 2000). high light intensity ofthe savanna open fields (Medina However, a clear comprehension ofthe process is not & Motta 1990) and the degree of environmental available yet, although high seed production and viability, disturbance (Pivello et al. 1999a and references seedling establishment, rapid growth and an efficient therein) could also favour its propagation in the celTado. vegetative reproduction have been pointed out as Among several other alien grasses, M. minlltiflora is important biological attributes for successful invader notably the most prominent species occupying natural species (Klink 1996). In addition to the factors reserves of the Brazilian cerrado, thus outcompeting previously cited, the high biomass production is also native herbs (pivello 1992). Results obtained by Pivello an important feature on competition. According to et al. (l999a) in one preserved area of cerrado in

I. Sec;:ao de Fisiologia e Bioqufmica de Plantas, Instituto de Botanica. Caixa Postal 4005, 0 I061-970 Sao Paulo, SP, Brasil. 2. Corresponding author: [email protected] 152 Hoehnea 29(2), 2002 southeastern Brazil showed that this species has similar species of Asteraceae, Poaceae and Leguminosae phytossociological patterns and spatial distribution (Mantovani & Martins 1993). when compared to the native grass Echinolaena of Echinolaena inflexa and Melinis inflexa (Poir.) Chase. minutiflora were harvested in the Biological Reserve Rapid changes in soluble carbohydrate metabolism of Moji-Guayu during summer and winter, in the underground organs ofnative herbaceous species corresponding to wet and dry seasons, respectively. from the cerrado (Figueiredo-Ribeiro & Dietrich 1983), £. inflexa is a perennial, rhizomatous grass species in addition to the accumulation of high amounts of native from the cerrado. It occupies both shaded (KJink fructans, have been considered as adaptive features & Joly 1989) and sunny habitats and exhibits C-3 ofthe plants to survive under unfavourable conditions, photosynthetic metabolism (Medina et al. 1999), particularly related to low temperature and drought differently from M. minutij7.ora, a C-4 species that (Figueiredo-Ribeiro et al. 1991, Tertuliano & occurs mainly in sunny and disturbed areas (Filgueiras Figueiredo-Ribeiro 1993, Vieira & Figueiredo-Ribeiro 1990, Pivello et al. 1999b). In the sampling site 1993, Carvalho et al. 1997). According to Mc Cue & E. inflexa plants flowered during summer, while Hanson (1990), the accumulation of several M. minutiflora flowered mainly in winter. Plants were metabolites, including fructans and polyols or sugar harvested in a sunny habitat from an area close to a alcohols in plants could be one indication of an track besides the border of the reserve. alternative metabolic mechanism operating in response From each of two species, tillers with the same to adverse environmental conditions, mainly drought. number of leaves were harvested from four plants In the present work we describe changes in randomly chosen ofeach species. The harvested tillers soluble carbohydrates from leaf blades, leaf sheaths represented the predominant phenological phase ofthe and stems of Echinolaena inflexa and Melinis species in the area. The sampling was performed minutiflora during winter and summer aiming to assess between 5 and 6 hours after sunrise. the role of those sugars in the association of both Carbohydrate extraction and analysis: immediately species in the cerrado. after harvesting, intact plants were hand cleaned from soil particles and placed in thermal boxes containing Material and methods solid CO2 (dry ice). In the laboratory they were separated into leaf blades, leaf sheaths and stems, Study site and studied species: the Biological Station constituting different samples, which were of Moji-Guayu (SP, Brazil) is a border cerrado area immediately wrapped in aluminium foil, frozen, occupying 343 ha within the rectangle 22°15'- 22°16'S Iyophilised and then finely ground through a 0.5 mm and 47°08'- 47°12'W. The climate fits into Koppen's screen in a Tecator-Cyclotec mill (USA). Carbohydrate Cwa. The soil is deep, acid and sandy with little organic extraction was performed using 5 mg cm-3 deionised matter and nutritionally poor. The altitude varies from water 95°C for 15 min, followed by centrifugation for 560 m to 700 m. The monthly temperature and rainfall 15 min at 1500 x g. This procedure was repeated twice. records registered over the years of 1996 and 1997, Supernatants were pooled and the pH adjusted to period when plants were harvested, ranged from 22.9°C neutrality before concentrating under vacuum at 37°C to 34.9°C during summer and from 10.4 °C to 30°C (Chatterton & Harrison 1997). The extracts were during winter; and from 0 mm in winter to 275 mm deionised using Sep-Pack Acce11 Plus QMA and CM during the summer months, respectively. There is a cartridges and hydrophobic compounds were removed rather definite dry season, which coincides with the using Sep-Pack tC l8 cartridges. All cartridges used cooler months (Eiten 1972, Mantovani & Martins 1993). were supplied by Waters Chromatography Division of As reported by Nardoto et al. (1998), water content Millipore Co. (USA). decreases in the outer layers of the soil, reaching Total sugars were measured using the phenol­ values lower than the permanent wilting percentage sulphuric acid procedure (Dubois et al. 1956), using to commercial crops (-1.5 MPa, soil water potential) glucose as standard. at the end of the dry period. The vegetation is High-performance anion exchange predominantly open and varies from "campo cerrado" chromatography with pulsed amperometric to "cerrado" (sensu stricto). The herbaceous detection (HPAEC-PAD) was used to perform component ofthe cerrado flora is composed mainly of quantitative analysis on a CarboPac PA-l column M.G. Moraes, A. Souza, R.A.B. Pessoni, R.C.L. Figueiredo,Ribeiro: Sugars in grasses from the cerrado 153

(4 X 250 mm) in a Dionex System Mod. DX-300 summer and winter are shown in figure 1. For both (USA). Quantification of individual sugars was also species and for all analysed tissues WSC were performed according to Timmermans et al. (1994) significantly higher in winter (Tukey 0.05). Differences by the external standard method using authentic were found among the plant parts, the stems had the standards (Sigma). The elution program consisted higher WSC contents in both species, the values were of a sodium hydroxide gradient (1 cm3 min'l) of two fold higher than in the other tissues, reaching up 12 mol m,3 (0-2 min), 24 mol m,3 (2-5 min), to 50 mg g'l d wt in M. minutiflora (figure IB). 36 mol m,3 (5-9 min), 44 mol m,3 (9-13 min), Glucose, fructose and sucrose were the major sugars 54 mol m,3 (13-16 min), 62 mol m,3 (16-18 min), found in both species and when individually quantified 66 mol m,3 (18-22 min), 96 mol m,3 (22-28 min), by HPAEC-PAD (figure 2) predominated during 120 mol m,3 (28-40 min), 140 mol m,3 (40-41 min), winter, except for sucrose in leaf blades and sheaths 12 mol m,3 (41-43 min). Oligo and polysaccharides of M. minutiflora (figure 2F). Higher proportions of were also qualitatively analysed on a CarboPac PA sucrose in the stems of both species were observed 100 column (4 x 250 mm), using a sodium acetate (figures 2E, 2F). gradient in 150 mol m,3 sodium hydroxide (1 cm3 min-I). The elution program consisted of 25 mol m,3 (0-4 min), 25 mol m,3 to 225 mol m,3 so Echinolaena inflexa (4-25 min), 225 mol m,3 to 500 mol m,3 (25-27 min) A and 25 mol m,3 (27-30 min). The applied PAD -::-40 potentials for El (500 ms), E2 (100 ms) and E3 ~ Aa (50 ms) were 0.1,0.6 and -0.6 V, respectively, and '0 'bI) the output range was 1 ~c. Pooled extracts were eo 30 submitted to gel filtration chromatography on 5 Ab Toyopearl HW-40S TSK (2.5 x 93.0 cm) coupled 20 a::l to a refractometer, to separate pools of sugars with cu'" ~ ~ degree of polimerisation (DP) 3 from DP 4. ~ 10 The low DP pool, which contained the weakly ionizable sugars, was analysed on a CarboPac MA-l column (4 x 250 mm) eluted with 500 mol m,3 o bl sh st sodium hydroxide (0.4 cm3 min,I). The applied PAD potentials for El (500 ms), E2 (100 ms) and E3 Melinis minutiflora Aa (50 ms) were 0.05,0.65 and -0.10 V, respectively, so and the output range was 3 ~c. B The identification of sugars was performed by co-chromatography with standards and by comparison with retention times ofauthentic standards (Sigma) of 'bI) 30 glucose, fructose, myo-inositol, sucrose, raffinose, bI) stachyose, maltose and maltose-based oligosaccharides 5 (DP3-7). Extracts from tubers of Helianthus 20 a::l tuberosus, leaves of Poa ampla and bulbs of Allium OJ'" cepa and purified galactinol were also used for ~ 10 comparison. Quantitative results were submitted to analysis of variance (ANOVA) in a factorial design and the o bl sh st means were compared by Tukey test (0.05). Figure I. Total water,soluble carbohydrate contents in leaf blades Results (hI), leaf sheaths ( h) and stems (st) of Echil/o/aena injlexa (A) and Me/iI/is minutijlora (B) during summer (_) and winter (D). The contents of water-soluble carbohydrates Bars represent standard error and, where not shown, they were (WSC) in leaf blades, leaf sheaths and stems of smaller than the symbol. Capital letters compare seasons and Echinolaena injlexa and Melinis minutiflora during small letters compare plant parts by Tukey test (0.05). 154 Hoehnea 29(2), 2002

Considering the total amounts of soluble The chromatographic profiles of WSC on carbohydrates present in the aerial parts and in the CarboPac PA-l column for both species were also underground organs of E. injlexa and M. minutiflora, very sintilar in winter, differing only in the proportions a similar pattern of distribution was found for both of sugar components (figure 3). Besides glucose, species in winter (table 1), whilst in summer, the fructose and sucrose, polyols (mainly myo-inositol and distribution of carbohydrates between shoot and root galactinol - see table 2) and oligosaccharides from differed significantly, sugars being allocated mainly to series other than those based on fructose (fructans) aerial parts in M. minutiflora. were present, being identified as raffinose, stachyose

Echinolaena inflexa Melinis minu.tijlora

A B ~ Aa '"Cl -: bJ) Aa bJ) Aa E Aa ~ C,) V) 0 u ~ ", 6 0 __LJ__ o bl 5h 51 bl 5h 51

D ,..., C ,..., ~ ~ '"Cl '"Cl -: -: Aa OIl OIl .sOIl .sbJ) C,) C,) V) V) 0 g u u 2 :J.... LJ., LJ.,

bl 5h 51 bl 5h 51

Aa ,..., ,..., ~ E ~ F '"Cl '"Cl -: -: OIl OIl .sOIl Aa .sOIl C,) .., V) V) ....0 e u u ", :J en en Ab ~, t::::::l_

bl 5h 51 bl 5h 51

Figure 2. Contents of glucose (A, B), fructose (C, D), and sucrose (E, F) quantified by HPAEC-PAD, in leaf blades (hI), leaf sheaths (sh) and stems (st) of Echil1o/aella illj1exa and Me/illis lIlillutiflora during ummer (.) and winter (0). Bars repre ent standard error and, where not shown, they were smaller than the symbol. Capital letters compare seasons and smalllcllers compare plant parts by Tukey test (0.05). M.G. Moraes, A. Souza, R.A.B. Pessoni, R.C.L. Figueiredo-Ribeiro: Sugars in grasses from the cerrado 155

Table I. Total contents of water soluble carbohydrates (WSC) in aerial (shoot) and underground organs (root) of Echinolaena injlexa and Melinis minutiflora during summer and winter.

Species WSC (mg g-I d wt) Summer Winter Shoot Root Shoot Root

E. injlexa 66.66 ± 7.29 89.27 ± 10.69 42.59 ± 4.64 48.33 ± 3.57 M. minutiflora 77.37 ± 8.63 86.44 ± 25.61 66.53 ± 4.55 25.72 ± 3.73

and maltose (figure 3). Analysis on CarboPac PA­ to 70% of the structural dry weight (Chatterton et aI. 100 showed that one of those series, more clearly 1989). Neither E. inflexa nor M. minutiflora detected in E. inflexa (figure 4A), co-eluted with the accumulate fructans, differently from what was maltose-based oligosaccharide series. Quantification currently found in vegetative organs offorage grasses ofgalactinol and myo-inositol by HPAEC-PAD using and cereals from temperate climates (pollock & Cairns MA-l column showed that both cyc1itols were lO-fold 1991) and in underground organs ofAsteraceae from higher in E. inflexa (table 2). Fructans were not the cerrado (Figueiredo-Ribeiro et aI. 1991). detected in any tissue from E. inflexa and M. minutiflora, neither by HPAEC (figures 3, 4) nor GF by thin layer chromatography on silica gel plates (data 3750 not shown) performed according to Cairns and Pollock A (1988). 2750 4) V> C 0 0.. 1750 Table 2. Composition of sugar alcohols in leaf blades of V> 4).... Echinolaena inflexa and Melinis minutiflora. .... 0 tl £ 750 Species Sugar alcohol (mg gol d wt) 4) myo-Inositol Galactinol a M Summer Winter Summer Winter -250 0 10 20 30 40 E. inflexa 0.183 0.319 0.567 1.225 M. minutiflora 0.042 0.035 0.084 0.139 GF 3750

B Discussion 2750

4) The high production ofbiomass is one ofthe most on C 1750 important features for the co-existence of 8.on ....4) Echinolaena inflexa and Melinis minutiflora in the .... 9 750 Brazilian cerrado (Pivello et al. 1999 a, b). According u £ 4) to Kingston-Smith et al. (1998), biomass production is 51 M a IJt I.-vLJ \. "- " R , not only determined by photosynthetic capacity, but ·250 also by the way in which the products ofphotosynthesis 0 10 20 30 40 are partitioned and used in plant development. Retention time (min) Our results showed that, despite the distinct origin and photosynthetic metabolism, the two species reported here are quite similar concerning sugar Figure 3. HPAEC-PAD analysis of water-soluble carbohydrates 3 contents and composition. Both species showed low (10 mg d wt cm- ) from aerial parts Geaf blades + sheaths and stems) of Echinolaena injlexa (A) and Melinis minutiflora (B) levels of WSC in the aerial organs and roots and during winter using a PA-I column. Markers P, G, F, S, R, St and specially low levels when compared to temperate M refer to polyols, glucose, fructose, sucrose, raffinose, stachyose grasses, in which soluble carbohydrates can reach up and maltose, respectively, as compared to authentic standards. 156 Hoehnea 29(2), 2002

According to Chatterton et al. (1989) high sucrose Several physiological roles have been conferred concentrations and cool temperatures were not always to sugar alcohols, including protection against stresses prerequisites for fructan accumulation in intact leaves (Lewis 1984, Bohnert et al. 1995). The accumulation ofseveral cool-season grass species. Furthermore, the of these compounds is related to salinity and drought local concentration ofsucrose in a particular tissue or stress tolerance (Bohnert et at 1995), as well as low cell compartment is more important for fructan temperatures, protecting cell components from synthesis than the total amount ofsucrose accumulated oxidative damages (Smimoff & Cumbes 1989, Shen (Koroleva et al. 1998). Despite the increased levels et al. 1997). Besides the role as protective compounds of sucrose found in the aerial organs of E. inflexa and against stresses, some sugar alcohols conjugated to M. minutiflora during winter, fructans were not galactosyl units, like galactinol, may act as galactosyl detected in any tissues of these species. Taxonomic donors for synthesis ofmembers ofthe raffinose series implications of the absence of fructans in E. inflexa (Keller & Pharr 1996). In this study, myo-inositol and and M. minutiflora, both belonging to the subfamily galactinol were identified, and they can be related to , could also be considered since this raffinose synthesis, since raffinose was also identified subfamily is believed to be a starch accumulator in both species. Our results showed that the levels of (Smouter & Simpson 1989). galactinol and myo-inositol were higher in E. inflexa In leaves of E. inflexa and M. minutiflora the than in the alien species M. minutiflora, and this major WSC detected were glucose, fructose and characteristic could extend the range of strategies for sucrose, in addition to sugar alcohols and the survival ofthe native species in adverse environmental maltose-based oligosaccharide series, clearly detected conditions, mainly seasonal drought typically found in E. inflexa. The presence of these oligosaccharides during winter in the cerrado (Eiten 1972). could be due to hydrolysis of starch and deserves The establishment of grasses in the cerrado is further investigation, since accumulation of determined by their efficient mechanisms of maltose-based oligosaccharides in vegetative tissues propagation (Klink 1996). In spite ofthe higher seed has not been reported in the literature to the present. viability and faster germination presented by African E. injlexa clearly showed these oligomers in the leaf grasses in foreign soils, the vigorous underground blades, specially during winter (figure 4). rhizomes found in E. inflexa possibly contributes to

GFS GFS A B

oen C o R 0­ en R ~

0- .9 M

Bo o 4 5

o 10 20 30 0 10 20 30

Retention time (min)

Figure 4. HPAEC-PAD analysis ofwater-soluble carbohydrates (60 mg d wt cm·3) from leafblades ofEchinolaena inflexa (A) and Melinis minutiflora (B) during winter using a PA-l00 column. Markers G, F, S, R and M refer to glucose, fructose, sucrose, raffinose and maltose, respectively. Numbers indicate sugars that co-eluted with the malto-oligosaccharide homologous series. M.G. Moraes, A. Souza, R.A.B. Pessoni. R.C.L. Figueiredo-Ribeiro: Sugars in grasses frolll the cerrado 157

its wide distribution and abundance in the cerrado Chatterton, N.J. & Harrison, P.A. 1997. Fructan oligomers (Filgueiras et al. 1998). Furthermore, the high survival in Poa ampla. New Phytologist 136: 3-10. rate of E. inflexa seedlings in the cerrado is also Chatterton, N.J., Harrison, P.A., Bennett, J.H. & Asay, KH. favoured by their resistance to the attack of ants, in 1989. Carbohydrate partitioning in 185 accessions of opposition to alien grasses (Klink 1996). The Gramineae grown under warm and cool temperatures. similarities concerning water soluble carbohydrates Journal of Plant Physiology 134: 169-179. in E. infllexa and M. minutilfora, as shown in the Dubois, M., Gilles, A., Hamilton, J.K, Rebers, P.A. & Smith, present work, is an indication that both species could F. 1956. Colorimetric method for determination ofsugars be phytossociologically related, as previously found and related substances. Analytical Chemistry 28: 350-355. by Pivello et al. (l999a) working in another preserved Eiten, G. 1972. The cerrado vegetation ofBrazil. Botanical area ofcen·ado. The analysis of biomass distribution Review 38: 201-341. of both grasses growing at the Biological Station of Figueiredo-Ribeiro, R.e.L. & Dietrich, S.M.C. 1983. Sugar Moji-Guac;u (SP) will allow, in addition to other content and metabolic activities in cold-stored ecological parameters, the determination of the fragmented xylopodium of Ocimum nudicaule Benth. degree of association between them. var. anisifolia Giul. (Labiatae). Journal ofExperimental Botany 34: 476-483. Acknowledgements Figueiredo-Ribeiro, R.C.L., Isejima, E.M., Dias­ Tagliacozzo, G.M., Carvalho, M.A.M. & Dietrich, work was financially supported by FAPESP, This S.M.C. 1991. The physiological significance offructan CAPES (M.G. Moraes and R.A.B. Pessoni) and accumulation in Asteraceae from the cerrado. Ciencia e CNPq (A. Souza and R.C.L. Figueiredo-Ribeiro). Cultura 43: 443-446. Thanks are due to Tatiana Sendulsky from the Institute Filgueiras, T.S. 1990. Africanas do Brasil: gramfneas ofBotany (Sao Paulo) and Tarciso S. Filgueiras from introduzidas da Africa. Cadernos de Geociencias 5: 57-63. the Brazilian Institute of Geography and Statistics Filgueiras, T.S., Felfili, J.M., Silva-Jr, M.e. & Nogueira, (Brasflia), for valuable suggestions and taxonomic P.E. 1998. Floristic and structural comparison ofcerrado identification ofgrass species. We are also grateful to (stricto sensu) vegetation in central Brazil. In: F. Dallmeier Marisa Domingos and Maria Angela M. Carvalho, & J.A. Comiskey (eds.). Forest biodiversity in North, both from the Institute of Botany (Sao Paulo), for Central and South America and Caribbean: research and valuable discussions. monitoring. UNESCO, Paris, pp. 633-648. Keller, F. & Pharr, D.M. 1996. Metabolism ofcarbohydrates Literature cited in sinks and sources: galactosyl-sucrose oligosaccharides.ln: E. Zamski & A.A. Schaeffer (eds.). Anten, N.P.R., Werger, M.J.A. & Medina, E. 1998. Nitrogen Photoassimilate distribution in plants and crops. Marcel distribution and leaf area indices in relation to Dekker Inc., New York, pp.157-183. photosynthetic nitrogen use efficiency in savanna Kingston-Smith, A.H., GaItier, N., Pollock, e.J. & Foyer, grasses. Plant Ecology 138: 63-75. C.H. 1998. Soluble acid invertase activity in leaves is Bilbao, B. & Medina, E. 1990. Nitrogen-use efficiency for independent ofspecies differences in leafcarbohydrates, growth in a cultivated African grass and a native South diurnal sugar profiles and paths of phloem loading. New American pasture grass. Journal of Biogeography Phytologist 139: 283-292. 17:421-425. Klink, e.A. 1996. Germination and seedling establishment Bohnert, H.J., Nelson, D.E. & Jensen, R.G. 1995. oftwo native and one invading African grass species in Adaptations to environmental stresses. Plant Cell Braziliancerrado.JoumalofTropicalEcology 12: 39-147. 7: 1099-1111. Klink, e.A. & Joly, e.A. 1989. Identification and distribution Cairns, A.J. & Pollock, e.J. 1988. Fructan biosynthesis in of C3 and C4 grasses in open and shaded habitats in excised leaves of Lolium teJIIlllelltum L. II. Changes in Sao Paulo State, Brazil. Biotropica 21: 30-34. fructosyltransferase activity following excision and Koroleva, O.A., Farrar, J.F., Tomos, A.D. & Pollock, C.J. application of inhibitors of gene expression. New 1998. Carbohydrates in individual cells of epidermis, Phytologist 109: 407-413. mesophyll, and bundle sheath in barley leaves with Carvalho,M.A.M., Zaidan, L.B.P. & Dietrich, S.M.e. 1997. changed export or photosynthetic rate. Plant Physiology Growth and fructan content of plants of Vemo/lia 118: 1525-1532. herbacea (Asteraceae) regenerated from rhizophores. Lewis, D.H. 1984. Storage carbohydrates in vascular plants. NewPhytologist 136: 153-161. Cambridge University Press, Cambridge, 284 p. 158 Hoehnea 29(2), 2002

Mantovani, W. & Martins, F.R. 1993. Floristic of the Renvoize, S.A. 1984. The grasses ofBahia. Royal Botanical "cerrado" in the Moji Guac;:u Biological Reserve, Sao Gardens, Kew, 301 p. Paulo State. Acta Botanica Brasilica 7: 33-60. Shen, B., Jensen, RG. & Bohnert, H.J. 1997. Increased Mc Cue, K.F. & Hanson, A.D. 1990. Drought and salt salt and drought tolerance by d-ononitol production in tolerance: towards understanding and application. transgenic Nicotiana tabacl/Ill L. Plant Physiology 115: Trends in Biotechnology 8: 358-362. 1211-1219. Medina, Martinelli, L.A., Barbosa, & Victoria, RL. K, K Smouter, H. & Simpson, R.J. 1989. Occurrence offructans 1999. Natural abundance of 13C in tropical grasses from in the Gramineae (Poaceae). New Phytologist the INPA, Instituto Nacional de Pesquisas da Amazonia, Ill: 359-368. herbarium. Revista Brasileira de Botanica 22: 43-51. Medina, K & Motta, N. 1990. Metabolism and distribution Smirnoff, N. & Cumbes, Q.J. 1989. Hydroxyl radical of grasses in tropical flooded savannas in Venezuela. scaveging activity of compatible solutes. Journal ofTropical Ecology 6: 77-89. Phytochemistry 28: 1057-1060. Nardoto, G.B., Souza, M.P. & Franco, A.C. 1998. Tertuliano, M.F. & Figueiredo-Ribeiro, R.C.L. 1993. Estabelecimento e padr6es sazonais de produtividade Distribution offructose polymers in herbaceous species de Kielmeyera coriacea (Spr.) Mart. nos cerrados do of Asteraceae from the cerrado. New Phytologist Planalto Central: efeitos do estresse hfdrico e 123: 741-749. sombreamento. Revista Brasileira de Botanica Timmermans,J.W., Van Leeuwen, M.B., Tournois, H., De 21: 313-319. Wit, D. & Vliegenthart, J.F.G. 1994. Quantitative Pivello, V.R 1992. An expert system for the use ofprescribed analysis of the molecular weight distribution of inulin fires in the management of Brazilian savannas. Ph.D by means of anion exchange HPLC with pulsed Thesis, University ofLondon, Ascot, 276 p. amperometric detection. Journal of Carbohydrate Pivello, V.R, Carvalho, V.M.C., Lopes, P.F., Peccinini, A.A. Chemistry 13: 881-888. & Rosso, S. 1999a. Abundance and distribution of Vieira, C.C.J. & Figueiredo-Ribeiro, R.C.L. 1993. native and alien grasses in a "cerrado"(Brazilian Fructose-containing carbohydrates in the tuberous root savanna) biological reserve. Biotropica 31: 71-82. ofGOll1phrena macrocephala St.-Hi!. (Amaranthaceae) Pivello, V.R., Shida, C.N. & Meirelles, S.T. 1999b. Alien at different phenological phases. Plant, Cell & grasses in Brazilian savannas: a threat to the biodiversity. Environment 16: 919-928. Biodiversity & Conservation 8: 1281-1294. Williams, D.G. & Baruch, Z. 2000. African grass invasion Pollock, C.J. & Cairns, A.J. 1991. Fructan metabolism in grasses and cereals. Annual Review ofPlant Physiology in the Americas: ecosystem consequences and the role 42:77-101. ofecophysiology. Biological Invasions 2: 123-140.