Síntese de prolina e resposta fisiológica de genótipos de mandioca sob salinidade in vitro

Milena Nascimento Cardoso,Caroline de Araújo Machado,Ana Veruska Cruz da Silva Muniz,Bruno Trindade Cardoso,Ana da Silva Ledo,Annie Carolina Araújo de Oliveira,Paulo Sérgio Neves dos Santos,Leila Albuquerque Resende Oliveira,Aparecida Gomes de Araújo

doi:10.1590/0103-8478cr20170175

Abstract

ABSTRACT: The objective of this research was to evaluate the proline synthesis and physiological response of cassava genotypes which were micro propagated and induced to salinity stress in vitro. Micro cuttings of approximately 1.0cm long with a single bud of genotypes TBRS Tapioqueira, BRS Verdinha and Lagoão which were previously established in vitro were inoculated in a MS medium containing different concentrations of NaCl (0; 25; 50; 75; 100mM) and were analyzed after 90th day for: number of roots, number of leaves and shoot dry mass. The proline content of BRS Tapioqueira and Lagoão was assessed at 30th, 60th and 90th day. There was no analysis of proline of the variety Verdinha because of the contamination of the explants. The experimental design was completely randomized in double factorial scheme (3 genotypes x 5 salt treatments), with seven repetitions for growth variables. For comparing proline content, completely randomized design was used in a plot subdivided in time, with genotype and NaCl factors in plot and time in subplot, with two repetitions. For r time and genotypes Tukey test (P<0,05) was used and for NaCl levels regression test (P<0,05). Salinity affected the growth of all varieties; although, BRS Tapioqueira and BRS Verdinha were less affected by induced salt stress. There was an increase in the accumulation of proline from the salt increment, this synthesis of proline being a biochemical indicator of salt stress in cassava plants cultivated in vitro.

Highlights

Cassava (Manihot esculenta Crantz), belongs to the class of dicotyledons, of the Euphorbiales order, Euphorbiaceae family, Manihot genus
Proline content was assessed only for BRS Tapioqueira and BRS Lagoão cultivars due to high bacterial contamination of BRS Verdinha on the proliferation phase
Free proline content was determined according to BATES et al (1973) modified by replacing the centrifuge filtration of the extracts

Summary

Introduction

Cassava (Manihot esculenta Crantz), belongs to the class of dicotyledons, of the Euphorbiales order, Euphorbiaceae family, Manihot genus. The Northeast region has characteristically saline soils (NOBREGA et al, 2012), causing damages to the productions, such as cassava culture. Among the mechanisms of tolerance to salt stress, plants stand out for their osmoregulation, which includes an increase in the concentration of solutes in the cells. These play a key role in osmotic balance, protection of enzymes in the presence of high concentrations of electrolytes in the cytoplasm (GREENWAY & MUNNS, 1980).

Objectives

Methods

Results