Embryo responses to extreme water events provide insights into the behavior of Butia capitata (Arecaceae) seed banks during hydration cycles

• Published in: Environmental and experimental botany Vol. 169; p. 103904
• Main Authors: Gonçalves, Bruno Guilherme, Ribeiro, Leonardo Monteiro, Dias, Daiane Souza, Mazzottini-dos-Santos, Hellen Cássia, Martins, Cristina de Paula Santos, Lopes, Paulo Sérgio Nascimento, Mercadante-Simões, Maria Olívia
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.01.2020
• Subjects: ABA; abscisic acid; Arecaceae; buried seeds; Butia capitata; calcium; catalase; cell structures; cerrado; ecosystems; electrical conductivity; enzyme activity; Fast hydration; hydrogen peroxide; leaching; magnesium; Neotropics; Oxidative stress; potassium; savannas; seed dormancy; superoxide anion; superoxide dismutase; ultrastructure; viability; vigor; water potential; Water stress; ABA; Oxidative stress; Fast hydration; CAT; Arecaceae; APX; SOD; Water stress; GPX; ψw
• ISSN: 0098-8472; 1873-7307
• DOI: 10.1016/j.envexpbot.2019.103904

•Butia capitata embryos were subjected to water stress (WS) and fast hydration (FH).•Protein reserves, SOD activity, and ABA biosynthesis are related to WS tolerance.•Biophysical damage to cell structure cause viability losses under severe WS.•Tolerance to WS and FH is crucial to the resilience of B. capitata seed banks. Dormant seed embryos in seed banks can experience hydration cycles that subject them to water stress (WS) and then fast hydration (FH). Physiological and cytological aspects of embryos of the Cerrado (neotropical savanna) palm Butia capitata were evaluated when subjected to osmotically induced WS and FH. The water potential (ψw), viability, and vigor of dehydrated or hydrated embryos were determined after immersion in osmotic solutions. Embryos were submitted to FH (ψw =0 MPa), moderate WS (ψw = −1 and −2 MPa), and severe WS (ψw = −2 and −4 MPa). Indicators of oxidative stress (H2O2, O2−, MDA, and CAT, SOD, and APX activities), membrane functionality (electrical conductivity and leaching of K+, Mg2+, and Ca2+), and ABA content were evaluated. The ultrastructures of dehydrated embryos and hydrated embryos submitted to ψw = 0, −1, and −2 MPa were evaluated. Dehydrated embryos (ψw = −8.5 MPa) showed high tolerance to WS that was related to their abundant protein reserves, SOD activities, and high ABA contents. Embryos tolerate FH and hydration makes ψw = −0.2 MPa. Hydrated embryos also show high tolerance to WS, which is related to their control of oxidative stress and increases in their ABA contents. Loss of viability under severe WS occurs associated with the blockage of protein mobilization, loss of membrane functionality, and the collapse of cellular structure. Embryo tolerance to WS and FH is crucial to the resilience of B. capitata seed banks exposed to hydration cycles in the seasonal Cerrado biome environment.