Comparative gene expression profiling during in vitro regeneration in two coconut cultivars

Bhavyashree Udyawar,Rajesh Krishna,Rachana Edathil,Anitha Karun,Lakshmi Jayaraj

doi:10.9755/ejfa.2016-01-066

Bhavyashree Udyawar, Rajesh Krishna + Show 3 more

Open Access

https://doi.org/10.9755/ejfa.2016-01-066

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Abstract

Coconut is a highly recalcitrant species with respect to tissue culture. The present study was carried out to compare the culture response from shoot meristem explants and gene expression patterns during various in vitro developmental stages in two cultivars of coconut viz. WCT (West Coast Tall) and COD (Chowghat Orange Dwarf) using RT-qPCR. Calli were obtained from shoot meristem explants and expression patterns of eight genes at different development stages in the two cultivars were analyzed using qRT-PCR. The results revealed enhanced expression of PKL, SERK and WUS was enhanced in embryogenic calli compared to non-embryogenic calli. High expression of GLP, ECP and GST could be observed in normal somatic embryos compared to abnormal somatic embryos. Enhanced expression of ECP, LEAFY, GLP and WRKY could be observed in normal meristemoids compared to aberrant meristemoids. When the two cultivars were compared, higher somatic embryogenesis was noticed in WCT compared to COD. Embryogenic calli of WCT showed higher expression of SERK, PKL and WUS compared to COD. Somatic embryos of COD showed high expression of GLP and GST compared to WCT, where as in case of ECP gene, higher expression was observed in WCT compared to COD. In case of WRKY and LEC, higher levels of expression were observed in meristemoids of WCT compared to COD. The results revealed significant differences in regeneration potential and gene expression patterns in the two coconut cultivars suggesting genotypic differences of cultivars to in vitro culture. These genes could therefore be useful as markers for somatic embryogenesis in coconut.

Highlights

The coconut palm (Cocos nucifera L.), belonging to the family Arecaceae, is a very important crop in tropical areas
RT-qPCR analyse was utilized to compare the expression patterns in the two cultivars. It was noticed a b c d e that, embryogenic calli of West Coast Tall (WCT) showed high expression of somatic embryogenesis receptor-like kinase (SERK), PKL and WUS compared to Chowghat Orange Dwarf (COD)
The present study describes a comparative study of induction of embryogenic calli and somatic embryogenesis and pattern of gene expression in various developmental stages of in vitro regeneration derived from shoot meristem explant in two coconut cultivars

Summary

Introduction

The coconut palm (Cocos nucifera L.), belonging to the family Arecaceae, is a very important crop in tropical areas. Crop improvement in coconut is difficult and time consuming due to its long tree pre-bearing age, high heterozygosity, long interval between generations and exclusively seed propagated nature (Arunachalam and Rajesh, 2008; Rajesh et al, 2014a). Since the availability of superior quality planting material is essential for crop improvement, tissue culture is considered as an important tool for the rapid multiplication of elite coconut genotypes (Fernando et al, 2010). Many explants have been tested, including immature inflorescence (Branton and Blake, 1984), immature embryos (Gupta et al, 1984), immature leaves (Raju et al, 1984; Buffard-Morel et al, 1992) and the results obtained indicate that regeneration can be achieved, but is rather difficult. Somatic embryos, developed from plumular explants, were capable of germination and subsequent development into plantlets, which could be successfully transferred to nursery (Chan et al, 1998; Rajesh et al, 2005, 2014a)

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