Physiological and isozyme alterations in lettuce seeds under different conditions and storage periods

Hugo César Rodrigues Moreira Catão,Pedro Henrique Faria Fonseca,Renato Mendes Guimarães,Luiz Antonio Augusto Gomes,Franciele Caixeta,Josué Clock Marodin

doi:10.1590/2317-1545v38n4163863

Hugo César Rodrigues Moreira Catão, Pedro Henrique Faria Fonseca + Show 4 more

Open Access

https://doi.org/10.1590/2317-1545v38n4163863

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Abstract

Abstract: The objective of the study was to determine the physiological and isozyme alterations in lettuce seeds submitted to different conditions and storage periods. We used a completely randomized design with four replications in a factorial arrangement with six lettuce cultivars (Everglades, Babá de Verão, Elisa, Grand Rapids, Hortência and Salinas 88) and four storage periods (30, 60, 90 and 120 days), on three storage rooms (15, 25 and 35 ° C). The physiological quality was evaluated by first and final germination count, emergence, and germination and emergence speed indexes. The isoenzyme expression of catalase (CAT), esterase (EST), alcohol dehydrogenase (ADH) and malate dehydrogenase (MDH) were determined. The physiological quality of lettuce seeds was preserved when stored at 15 ° C room temperature. The high room temperatures associated with higher storage periods cause a reduction in physiological quality and alterations in enzymatic patterns of CAT, EST, ADH and MDH. For seeds stored at 15 ° C, there were no physiological changes. The lettuce cultivars, especially Everglades, have different levels of tolerance to storage and isoenzyme expressions.

Highlights

Studying the expression of isoenzymes throughout the storage of seeds may be useful, since it allows the identification of variations related to abiotic factors
On tropical regions in general, the environmental conditions are adverse for the storage of seeds due to the high temperatures that may be associated with a high relative air humidity (Carvalho et al, 2014a)
A common practice among lettuce producers is, after sowing, they store the packages containing the rest of the seeds at inadequate locations, where the room temperature is usually high, which compromises the quality of the seeds for the sowing

Summary

Introduction

Studying the expression of isoenzymes throughout the storage of seeds may be useful, since it allows the identification of variations related to abiotic factors. The use of biochemical markers becomes a tool to select materials that tolerate high temperatures, which is indispensable to develop lettuce improvement programs (Lactuca sativa L.) for tropical and subtropical regions (Catão et al, 2014). On tropical regions in general, the environmental conditions are adverse for the storage of seeds due to the high temperatures that may be associated with a high relative air humidity (Carvalho et al, 2014a). The relative air humidity of the storage room and the water content of the seed, the maintenance of their quality during storage is influenced by the genotype (Martins‐Filho et al, 2001). A common practice among lettuce producers is, after sowing, they store the packages containing the rest of the seeds at inadequate locations, where the room temperature is usually high, which compromises the quality of the seeds for the sowing. As a consequence of these metabolic events, the breathing of the seed promotes an increase on the deterioration speed, and one of the first degradation events is the loss of permeability of the membrane, since it loses its selectiveness, and enzymes and proteins become less efficient on catalytic activities (Smith and Berjak, 1995)

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