In vitro organogenesis of rangpur lime

Leonardo Soriano,Maurel Behling,Eveline Carla Da Rocha Tavano,Francisco De Assis Alves Mourão Filho,Beatriz Madalena Januzzi Mendes

doi:10.1590/s0100-29452012000200006

Abstract

Rangpur lime (Citrus limonia Osbeck) in vitro organogenesis was studied based on explant type and cytokinin culture media supplementation. Four explants types collected from epicotyl or hypocotyl regions of in vitro germinated seedlings were evaluated. The epicotyl-derived explants consisted of epicotyl segments and the hypocotyl-derived explants consisted of the entire hypocotyl segment, the hypocotyl segment attached to a cotyledon fragment, and the hypocotyl segment divided longitudinally. The explants were cultured on EME culture medium supplemented with benzylaminopurine (0, 0.5, 1.0, or 1.5 mg L-1). The evaluation was performed after 6 weeks. Best results considering both the explant responsiveness and number of shoots developed per explants were obtained when epicotyl segments-derived explants were evaluated. Considering the explant responsiveness of hypocotyl segments-derived explants no difference was detected between the entire hypocotyl segment and the hypocotyl segment attached to a cotyledon fragment. Moreover, the percentage of responsive explants decreased when hypocotyl segments divided longitudinally were tested. No difference was detected for the number of shoots developed per explant considering the three types of hypocotyl-derived explants. Culture media supplementation with BAP was not essential for Rangpur lime in vitro organogenesis. However, adventitious shoot development was stimulated in concentrations between 0.5 - 1.0 mg L-1.

Highlights

Citrus genetic transformation has been studied since 1989 (KOBAYASHI; UCHIMIYA, 1989) with the production of transgenic plants of different citrus species and cultivars
Most citrus in vitro organogenesis protocols are based on the culture of young tissue, mainly epicotyls and intermodal segments (GARCIA-LUIS et al, 1999; MOURA et al, 2001) cultivated in culture media supplemented with cytokinin (BORDÓN et al, 2000; ALMEIDA et al, 2002)
Almeida et al (2002) and Costa et al (2004) reported an explant responsiveness of 60% when epicotyls segments of Rangpur lime were cultured in absence or low concentrations of benzylaminopurine (0.5 mg L-1), and higher concentrations of cytokinin inhibited in vitro organogenesis

Summary

Introduction

Citrus genetic transformation has been studied since 1989 (KOBAYASHI; UCHIMIYA, 1989) with the production of transgenic plants of different citrus species and cultivars. Rangpur lime (C. limonia), sour orange (C. aurantium), and volkamer lemon (C. volkameriana) are among the rootstocks cultivars which problems have been detected regarding genetic transformation These problems may be related with gene transfer process and to a low efficiency of in vitro organogenesis. When internodal segments were used as explant, the development of adventitious shoots was detected in 62% of the explants culture in culture media supplemented with 2.5 mg L-1 of BAP Comparing this numbers with values of explant responsiveness obtained for other genotypes, such as 95% for Troyer and Carrizo citrange (MOREIRA-DIAS et al, 2001; BORDÓN et al, 2000), 90% for grapefruit (COSTA et al, 2004), and 96% for C. aurantifolia (PÉREZ-MOLPHEBALCH; OCHOA-ALEJO, 1997) Rangpur lime can be considered a recalcitrant genotype

Objectives

Methods

Results