Proline and trehalose in maize seeds germinating under low osmotic potentials

Abstract

A B S T R A C TAlthough it is relatively well known that adult plants tend to accumulate proline and trehalose in their tissues as a physiological mechanism in response to drought, there is scarce information about the development of this physiological response in seeds. Thus, the objective of this research was to verify if maize seeds are able to develop mechanism of osmoprotection, when are germinating under low osmotic potential, and the possibility to use the levels of trehalose and proline in a defined seed part, aiming to differentiate genotypes regarding drought tolerance. The experiment was performed as a factorial arrangement of 2 x 5 (2 hybrids x 5 osmotic potential) within a completely randomized design, with four replicates. It was found that the proline content in the embryo axis of maize seeds germinating under water limitation is directly proportional to the intensity of this stress. Distinct hybrids show different proline levels accumulated in the embryo axis, when seeds are germinating under the same conditions of water limitation. The trehalose content tends to decrease in the embryo axis and in the endosperm of maize seeds germinating under increasing water limitation, but the reduction is not directly proportional to osmotic potential.Prolina e trealose em sementes de milho germinando em baixos potenciais osmóticos R E S U M O Embora seja relativamente bem conhecido que as plantas adultas tendem a acumular prolina e trealose como mecanismo fisiológico em resposta à seca, há pouca informação sobre o desenvolvimento desta resposta em sementes. Assim, esta pesquisa objetivou avaliar se sementes de milho são capazes de desenvolver mecanismos de osmoproteção quando postas para germinar em condições de baixos potenciais osmóticos, bem como a possibilidade de usar os níveis de trealose e prolina como indicadores bioquímicos para diferenciar genótipos quanto à tolerância à seca. O experimento constou de um esquema fatorial de 2 x 5 (2 híbridos x 5 potenciais osmóticos) conduzido em um delineamento inteiramente casualizado com quatro repetições. Observou-se que o teor de prolina no eixo do embrião de sementes de milho postas para germinar sob limitação hídrica, é diretamente proporcional à intensidade do estresse. Híbridos distintos mostram diferentes níveis de prolina no eixo embrionário quando as sementes germinam nas mesmas condições de limitação hídrica. O teor de trealose diminui, tanto no eixo embrionário como no endosperma de sementes de milho postas para germinar sob crescente limitação hídrica mas a redução não é diretamente proporcional à intensidade do estresse.

Effects of Epichloë sinensis Endophyte and Host Ecotype on Physiology of Festuca sinensis under Different Soil Moisture Conditions

“…The synthesis and accumulation of small molecular organic solutes, such as proline and soluble sugar, are the main tools of plant osmotic regulation [ 81 , 82 , 83 , 84 ]. Studies have shown that when plants are subjected to drought stress, proline in the symbionts can be converted into precursor compounds of loline or ergot alkaloids [ 85 , 86 , 87 ].…”

A Snapshot of the Trehalose Pathway During Seed Imbibition in Medicago truncatula Reveals Temporal- and Stress-Dependent Shifts in Gene Expression Patterns Associated With Metabolite Changes

“…Such a response in a short time further suggests for the role of trehalose as an energy source rather than osmoprotectant. Indeed, Queiroz and Cazetta (2016) showed that in maize seeds germinating under water restriction, trehalose was utilized instead of being accumulated. According to these authors, the sugar was preferentially used in energy metabolism for supporting germination and synthesis of proline in the embryo axis.…”

An Endohyphal Bacterium (Chitinophaga, Bacteroidetes) Alters Carbon Source Use by Fusarium keratoplasticum (F. solani Species Complex, Nectriaceae)

“…PS-EHB01 led to differential growth by F. keratoplasticum on most sugars, amino acids, and carboxylic acids, nearly all of which are relevant in plant biology. In particular, a number of substrates are important in the ecology of seeds, such as important global regulators (e.g., D-trehalose and myo -inositol; Loewus and Murthy, 2000 ; Grennan, 2007 ; Henry et al, 2014 ; Lunn et al, 2014 ), those metabolized or produced during seed imbibition and germination (e.g., D-trehalose, sucrose, D-raffinose, stachyose, dextrin, and L-asparagine; Atkins et al, 1975 ; Bewley and Black, 1978 ; Kuo et al, 1990 ; Queiroz and Cazetta, 2016 ), as well as those important in the metabolism of seed structural components such as the seed coat (e.g., D-mannose, L-arabinose, sucrose, D-raffinose, stachyose, myo -inositol, and L-alanine; Herold and Lewis, 1977 ; Bewley and Black, 1978 ; Kuo et al, 1990 ; Buckeridge et al, 2000 ; Loewus and Murthy, 2000 ; Lahuta et al, 2007 ; Kosina et al, 2013 ). The average difference in growth between EHB+ and EHB− strains, considering only those substrates on which we observed significant differences ( n = 64; Table 1 ) was = 0.3.…”