Somatic embryogenesis and plant regeneration capacity in Argentinean maize (Zea mays L.) inbred lines

Abstract

Somatic embryogenesis, which is still the method of choice for tissue culture, regeneration and transformation of maize, is largely considered highly genotype-dependent. The Hi II, a highly embryogenic genotype, has been extensively used in transformation protocols. However, this is not an inbred line; instead, it has a proportion of the undesirable A-188 background, and the progeny segregates for phenotypic characteristics and shows poor agronomic performance. In an effort to identify genotypes that combine a high somatic embryogenic response and good agronomic performance, we evaluated 48 advanced inbred lines developed at INTA. Callus development and somatic embryogenesis capacity were measured in 200 immature embryos per line. Embryogenic capacity [EC (mature somatic embryos/callus evaluated) x 100], Regeneration Capacity (RC) and Fertile Plant Recovery in greenhouse (FPR, fertile plants/regenerated plants) were recorded. A total of 17 lines reached an EC > 50%, and 14 out of those 17 lines regenerated seedlings. The FPR ranged between 50 and 100%. Also, we selected three promising lines with high agronomic performance, as alternatives to Hi II, in order to be included in a maize transformation scheme via somatic embryogenesis. In addition, we report the usefulness of Single Sequences Repeat (SSRs) in the determination of genetic diversity among 14 divergent lines for somatic embryogenesis response. The seven lines displaying good in vitro behaviour can be crossed to obtain hybrids combining desirable alleles for somatic embryogenesis response and different genetic backgrounds.

Arabidopsis Cyclin-Dependent Kinase Gene CDKG;2 is Involved in Organogenic Responses Induced in Vitro

“…Somatic embryogenesis was successfully induced from immature zygotic embryos cultured on Gamborg (B5) medium supplemented with 2,4-D (Gaj, 2001a,b;Kurczyńska et al, 2007;Fraś et al, 2008). Immature zygotic embryos are the ones mostly used as explants for direct and indirect formation of somatic embryos in various plant species, including Trifolium nigrescens (Konieczny et al, 2010), Helianthus annuus (Jach and Przywara, Żabicki et al (Yang et al, 2012) and Zea mays (González et al, 2012). In our work, using hypocotyls and cotyledons isolated from 3-day-old seedlings of Col-0 and a selected cdkg;2 mutant line cultured on MS medium with 2,4-D, only callus induction and proliferation was achieved.…”

miRNA Profiling and Its Role in Multi-Omics Regulatory Networks Connected with Somaclonal Variation in Cucumber (Cucumis sativus L.)

“…Until now, miRNAs have been studied more in the context of in vitro cultures rather than the phenomenon of variability. In vitro culture conditions such as culture medium, photoperiod or phytohormone ratio can be adjusted to promote somatic embryogenesis or organogenesis from induced callus [15]. The molecular pathway of shoot regeneration primarily includes phytohormones and genes related to shoot apical meristem [16].…”

Genetic transformation of the Brazilian BR 451 maize variety by the Agrobacterium tumefaciens method

“…Great efforts have been made to adapt gene transfer into cereals via A. tumefaciens as they are resistant to such maneuvers (FRAME et al, 2002;2011). This recalcitrance is related to two different aspects: a) the low in vitro response (CARVALHO et al, 1997;FRAME et al, 2006;GONZÁLES et al, 2012;GRANDO et al, 2013) e b) low explant sensibility to agrobacteria infection (VENNA et al, 2003;CARVALHO et al, 2004;WANG et al, 2007), thus restricting the number of transformed maize genotypes (GONZÁLEZ et al, 2012;OMBORI et al, 2014).…”

“…Therefore, it becomes necessary to adapt the A. tumefaciens-mediated transformation parameters to agronomically suitable genotypes, like varieties, hybrids and lines (FRAME et al, 2006;WANG et al, 2007;CARNEIRO et al, 2009;GONZÁLEZ et al, 2012).…”