Massal Induction of Carica papaya L. ^|^lsquo;Golden^|^rsquo; Somatic Embryos and Somaclone Screening by Flow Cytometry and Cytogenetic Analysis

Abstract

Summary Somatic embryogenesis is a relevant micropropagation technique in Carica papayaGolden in view of the difficulties met in conventional seed propagation and the lack of an effective method for early sex determination in this trioecious species. Considering the interest in large-scale production of C. papaya seedlings, we adapted a somatic embryogenesis procedure associating liquid system and immature zygotic embryo explants. This protocol markedly contributed to an increase in the yield of friable embryogenic calli, resulting in a large number of normal somatic embryos at various developmental stages. From these embryos, plantlets were regenerated and evaluated for occurrence of somaclonal variation. Flow cytometry screening revealed diploid (88%), tetraploid (6%), and aneuploid (6%) plantlets. Owing to an interest in the mass propagation of diploid individuals, the karyotype of these plantlets was also analyzed. With this approach, diploidy (2X=18) was confirmed and no structural aberrations were found. Considering the results and the applicability of large-scale production of somatic embryos in C. papaya, the tissue culture protocols shown here could be used for commercial purposes. Moreover, the cytometric and cytogenetic analyses were crucial for a rapid, reliable and conclusive evaluation of the genetic stability of C. papaya plantlets regenerated by somatic embryogenesis.

Somaclonal variations and their applications in horticultural crops improvement

“…A wide variety of tools are available for the detection and characterization of somaclonal variants which are primarily based on the differences in morphological traits (Pérez et al 2009, 2011; Nhut et al 2013), cytogenetical analysis for the determination of numerical and structural variation in the chromosomes (Clarindo et al 2012; Currais et al 2013; Abreu et al 2014), biochemical (Vujovic et al 2010; Kar et al 2014), molecular DNA markers (Krishna and Singh 2007; Pathak and Dhawan 2012; Hossain et al 2013; Bello-Bello et al 2014) or their combinations (Horáček et al 2013; Dey et al 2015; Stanišić et al 2015). The best test for assessing somaclonal variation is to fruit out the plants and conduct an extensive horticultural evaluation, which is unfortunately a long-term endeavor with woody fruit crops, particularly (Grosser et al 1996).…”

Medical Cannabis and Industrial Hemp Tissue Culture: Present Status and Future Potential

“…Although clonal propagation and maintenance of elite germplasm require a substantial genetic uniformity among in vitro regenerated plantlets, there may be a large possibility of genetic variations, called “somaclonal variation” among these plants and/or relative to the donor plants. Somaclonal variation is commonly a result of genetic alterations and changes in the new in vitro plants’ epigenetics compared to the original source plants ( Miguel and Marum, 2011 ; Abreu et al, 2014 ). The frequency and nature of somaclonal variation in vitro culture can be influenced by different factors, such as explant source, genotype, in vitro techniques, in vitro growth conditions, length of the culture period, and the number of subcultures.…”

“…Variations between regenerated and donor plants can be exhibited at phenotypic, cytological, biochemical, and genetic/epigenetic levels ( Hillig, 2005 ; Miguel and Marum, 2011 ; Smulders and de Klerk, 2011 ; Abreu et al, 2014 ). These variations can be determined through different approaches, such as morphological, cytological, biochemical, and molecular analyses ( Figure 7 ).…”

Advances observed in papaya tree propagation

“…In all of these studies, the efficiency of protocols is directly related to the type of explant and genotypes used (CHEN et al, 1987;FITCH, 1993;VILASINI et al, 2000;CLARINDO et al, 2008;MALABADI et al, 2011;RAZALI;DREW, 2014). In addition, regardless of explant and genotype used, C. papaya has been responsive to SE (VILASINI et al, 2000;CLARINDO et al, 2008;ABREU et al, 2014). It is also worth noting that the use of MS medium at different concentrations (MURASHIG;SKOOG, 1962) supplemented with these phytohormones is predominant among SE protocols developed until now (ANANDAN et al, 2012).…”