Aspectos fisiológicos, anatômicos e ultra-estruturais do rizoma de Costus arabicus L. (Costaceae) sob condições de déficit hídrico

Abstract

-(Physiological, anatomical and ultrastructural aspects of the rhizome of Costus arabicus L. (Costaceae) under water defi cit conditions). Costus arabicus L. is an herbaceous species, native to the forest that accumulates starch in the rhizome as the main reserve carbohydrate. Water stress is one the most important environmental factor that regulates plant growth and development, leading to changes in physiological, biochemical and anatomical traits. The aim of this study was to evaluate the effect of water defi cit on the anatomy, carbohydrate concentration and ultrastructure of starch grains of the rhizome of Costus arabicus L. through the following water regimes: plants irrigated daily and every seven (7d) and 15 days (15d). Anatomical and ultrastructural traits of the rhizome, relative water content in leaves (RWC), leaf water potential (Ψw), osmotic potential of the rhizome (Ψo), total soluble sugars (TSS), reducing sugars (RS) and starch of the rhizome were evaluated. We observed signifi cant reductions in Ψw and Ψs in 15d plants, but with small variations in the RWC. The anatomical analysis showed that the rhizome is covered by epidermis or stratifi ed cork and there is a delimitation between the cortical and vascular regions. We detected the presence of numerous starch grains and idioblasts with phenolic contents in the parenchyma of the two regions. Changes in the anatomy of the rhizomes were only observed in plants irrigated every 15 days, in which cells of covering tissue and the outer cortical layers became more fl attened and sinuous walls; however, no ultrastructural differences were observed on the starch grains. The water defi cit imposed was suffi cient to generate physiological, biochemical and anatomical changes in plants of C. arabicus L. Such alterations suggest the occurence of an avoidance mechanism and that anatomical changes were dependent of the intensity and duration of water defi cit. Key words: drought, starch, water stress RESUMO -(Aspectos fi siológicos, anatômicos e ultra-estruturais do rizoma de Costus arabicus L. (Costaceae) sob condições de défi cit hídrico). Costus arabicus L. é uma espécie herbácea, nativa de mata, que acumula em seu rizoma amido como principal carboidrato de reserva. A seca é um dos fatores ambientais que pode regular o crescimento e o desenvolvimento das plantas, levando a alterações nas características fi siológicas, bioquímicas e anatômicas. Este trabalho objetivou avaliar a infl uência do défi cit hídrico na anatomia, no conteúdo de carboidratos e na ultra-estrutura dos grãos de amido do rizoma de Costus arabicus L. submetidos aos ciclos de rega diário (Controle) e a cada sete (7d) e 15 dias (15d). Foram avaliados aspectos anatômicos e ultra-estruturais do rizoma, conteúdo relativo de água nas folhas (CRA), potencial hídrico foliar (Ψw), potencial osmótico do rizoma (Ψs), açúcares solúveis totais (AST) e redutores (AR) e amido do rizoma. Observaram-se reduções signifi cativas do Ψw e do Ψs nas plantas 15d, porém com pequenas variações no CRA. An...

Structural and metabolic changes in rhizophores of the Cerrado species Chrysolaena obovata (Less.) Dematt. as influenced by drought and re-watering

“…Cellular collapse of covering tissue and outer cortical layers was also observed in rhizomes of Costus arabicus , a starch accumulating species, under water deficit. The degree of tissue damage was dependent on the intensity and duration of the water deficit (Costa et al, 2012 ). Additionally, Zhang et al ( 2010 ) reported that water deficit could affect size distribution of starch granules in wheat cultivars.…”

Ecophysiological response of Astronium fraxinifolium (Anacardiaceae) in degraded and non-degraded brazilian Cerrado

“…Thus, environmental factor such as soil conditions, water, light, temperature, etc., influence the morphophysiological characteristics of the plants and so, environmental changes can cause structural changes (Costa et al 2012;Alameda & Villar 2012;Aref et al 2013;Cambi et al 2016) and physiological (Warren et al 2011;Alameda & Villar 2012;Lu et al 2012;Cambi et al 2016;Wang et al 2018).…”