Seasonal dynamics of non‐structural carbohydrates in bulbs and shoots of the geophyte Galanthus nivalis

Abstract

Seasonal dynamics of non-structural carbohydrates were studied in Galanthus nivalis L. over a 2-year period. The plants were collected in the field and separated into above- and below-ground biomass. The polysaccharide fraction of the bulbs consisted of fructans and starch. Seasonal variations suggest that the polysaccharides were utilized for carbon and energy supply for re-growth and flower development. With the re-sprouting of the bulbs in autumn the fructans within the bulbs were depolymerized and an increase of low degree of polymerization fructans as well as sucrose was observable. Within shoots the major polysaccharides were fructans, the starch content was much lower. Gas liquid chromatography and high-performance, anion-exchange chromatographyanalysis of the fructan fraction revealed that the fructans within the shoots were predominantly those with a low degree of polymerization. In addition to the two polysaccharides the other dominant sugar in shoots was sucrose. During the period of slow re-growth and flowering, fructan and starch pools were depleted to different degrees. Calculation of the difference between the carbohydrate content at the start of visible growth and at the time of lowest content revealed that the starch pool showed a higher depletion than the fructan pool. During the re-growth periods in 1996/97 and 1997/98 fructans were catabolized by 39 and 32% only, whereas the starch pool was depleted by 92% (1996/97) and 79% (1997/98), respectively. During rapid shoot growth and fruiting, the bulbs and above-ground organs appeared to be competing sinks for the photosynthetically fixed carbon. Refilling of the bulbs carbohydrate reserve started in February/March In shoots, the period of refilling the bulbs was characterized by a low content of oligosaccarides and a high content of hexoses.

Why Snowdrop (Galanthus nivalis L.) tepals have green marks?

“…The specific sink for the carbon assimilated by the Galanthus inflorescence cannot be exactly predicted from the data set collected, but the expanding basal leaves are expected to invest most of the assimilates both on their own growth and on filling the bulbs. During rapid shoot growth and fruiting, the bulbs and the above-ground organs were even assumed to be competing sinks for the photosynthetically fixed carbon, because refilling of carbohydrate reserves of the bulbs starts in February/ March (Orthen and Wehrmeyer, 2004).…”

Comparison of the water-soluble carbohydrate composition and fructan structures of Agave tequilana plants of different ages

“…Avila-Fernandez et al (2007) have found that in A. tequilana plants, the enzyme 1-SST showed an estimated kcat value of 260 min À1 , corresponding to a lower turnover number than the value of kcat observed for 1-SST from H. tuberosus (1566 min À1 ). This could explain why in A. tequilana plants the accumulation of sugars is slower with longer times for harvest (8-12 years) than other typical fructan producing plants ( AvilaFernandez et al, 2009;Cedeño, 1995;Monti et al, 2005;Orthen & Wehrmeyer, 2004;Saengthongpinit & Sajjaanantakul, 2005;Shiomi et al, 2005;Wilson et al, 2004). In Fig.…”

“…1, it can be inferred that at 2 years, the synthesis of fructans was beginning and the accumulation of fructans as reserve carbohydrate was in the initial phase. The increase of sugar accumulated as fructans has been observed also in physiological process of multiple plants, like the seeds maturation process of onion (Allium cepa L. ''W202"), during re-growth and flower development of Galanthus nivalis bulbs and during maturation process of Cichorium intybus L. and Helianthus tuberosus L. (Monti et al, 2005;Orthen & Wehrmeyer, 2004;Saengthongpinit & Sajjaanantakul, 2005;Shiomi et al, 2005;Wilson et al, 2004). The common characteristic of the accumulation processes in these plants is that normally the accumulated fructans are linear with b(2?1) linkages whereas in A. tequilana and other graminans like Urginea maritima they are highly branched (Spies et al, 1992).…”

“…Thus our results are in agreement with this previous behaviour observed. The polymerisation and depolymerisation of fructans is a phenomena observed in most of the fructan accumulating plants and is associated in most of the cases to regulation of water imbalances, adaptation to cold weather or to accumulation of reserve carbohydrate and post utilisation as an energy source for flowering or re-growth (Dias-Tagliacozzo et al, 2004;Monti et al, 2005;Orthen & Wehrmeyer, 2004;Saengthongpinit & Sajjaanantakul, 2005;Shiomi et al, 2005;Tolsma, Read, & Tolhurst, 2007;Vijn & Smeekens, 1999;Wilson et al, 2004). Therefore, probably the behaviour observed of fructans distribution of A. tequilana plants from 2 to 6½ was due to a fructan accumulation process, which is a required step for agave plants before flowering.…”

“…The comparison of fructan linkage analysis between A. tequilana, Agave potatorum, Agave cantala, Agave fourcroydes and Agave angustifolia showed differences in the proportions of glucose polymerised, as well as in the proportions of b(2?6) and b(2?1) linkages of the principal chains (Mancilla-Margalli & Lopez, 2006). In addition, for other plants different to Agavaceae family, the synthesis of fructans is influenced by the production region, the soil nutrients, the plant variety, the seasonal changes, the water regime and the harvest time (Dias-Tagliacozzo, Itaya, Machado de Carvalho, Figueiredo-Ribeiro, & Dietrich, 2004;Faustini-Cuzzuol, MachadoCarvalho, Penteado-Zaidan, & Roberto-Furlani, 2005;Livingstone, Premakumar, & Tallury, 2006;Martínez-Noël, Tognetti, Nagaraj, Wiemken, & Pontis, 2006;Monti, Amaducci, Pritoni, & Venturi, 2005;Morcuende, Kostadinova, Pérez, & Martínez-Carrasco, 2005;Orthen & Wehrmeyer, 2004;Saengthongpinit & Sajjaanantakul, 2005;Shiomi, Benkeblia, Onodera, & Kawazoe, 2005;Wilson, Smith, & Yonts, 2004). To our knowledge, there is only one report about the influence on A. tequilana age over the tequila fermentation process (Pinal et al, 2009).…”