Programa de Pós Graduação em Biodiversidade Vegetal, Instituto de Ciências Biológicas, Universidade Federal de Goiás, Av. Esperança s/n, Campus Samambaia, Goiânia, GO 74690-900, Brazil.
Instituto de Química, Universidade Federal de Goiás, Goiânia, GO 74690-900, Brazil.
Sci Total Environ. 2017 Nov 15;598:404-412. doi: 10.1016/j.scitotenv.2017.04.100. Epub 2017 Apr 25.
Cerrado is a floristically rich savanna in Brazil, whose vegetation consists of a physiognomic mosaic, influenced by rainfall seasonality. In the dry season rainfall is substantially lower and reduces soil water supply, mainly for herbs and subshrubs. Climatic seasonal variations may well define phenological shifts and induce fluctuations of plant reserve pools. Some Cerrado native species have thickened underground organs that bear buds and store reserves, as adaptive features to enable plant survival following environmental stresses. Asteraceae species accumulate fructans in storage organs, which are not only reserve, but also protecting compounds against the effects of cold and drought. Ichthyothere terminalis is one Asteraceae species abundant in cerrado rupestre, with underground organs consisting of thickened orthogravitropic and diagravitropic roots. The objectives of this study were to analyze how abiotic environmental factors and plant phenology influence fructan dynamics in field grown plants, and verify if fructan metabolism differs in both root types for one year. I. terminalis accumulates inulin-type fructans in 10-40% of the dry mass in both root types. Fructan dynamics have similar patterns described for other Asteraceae species, exhibiting a proportional increase of polysaccharides with the senescence of the aerial organs. Multivariate analyzes showed that, as rainfall decreased, environmental factors had a stronger influence on metabolite levels than phenological shifts in both root types. Only slight differences were found in fructan dynamics between orthogravitropic and diagravitropic roots, suggesting they may have similar fructan metabolism regulation. However, these small differences may reflect distinct microclimatic conditions in both root types and also represent the influence of sink strength.
塞拉多是巴西一种植物种类丰富的热带稀树草原，其植被由受季节性降雨影响的生理镶嵌体组成。在旱季，降雨量大幅下降，减少了土壤水分供应，主要影响草本植物和亚灌木。气候季节性变化很可能会定义物候转变，并导致植物储备池的波动。一些塞拉多原生种的地下器官会变厚，形成芽和储存储备，这是适应环境压力的生存策略。菊科植物在储存器官中积累果聚糖，这些果聚糖不仅是储备物质，也是保护化合物，防止其受到寒冷和干旱的影响。Ichthyothere terminalis 是塞拉多岩生植被中丰富的菊科植物，其地下器官由增厚的正交和背地根组成。本研究的目的是分析非生物环境因素和植物物候如何影响田间生长植物的果聚糖动态，并验证一年中两种根类型的果聚糖代谢是否存在差异。I. terminalis 在正交和背地根中均以 10-40%的干重积累菊糖型果聚糖。果聚糖动态与其他菊科植物相似，表现为随着地上器官衰老，多糖的比例增加。多变量分析表明，随着降雨量的减少，环境因素对代谢物水平的影响比两种根类型的物候变化更大。正交和背地根之间的果聚糖动态仅存在细微差异，表明它们可能具有相似的果聚糖代谢调节。然而，这些微小的差异可能反映了两种根类型不同的微气候条件，也代表了汇强的影响。
