Transgenic lines of Begonia maculata generated by ectopic expression of PttKN1

Abstract

KNOX (KNOTTED1-like homeobox) genes encode homeodomain-containing transcription factors which play crucial roles in meristem maintenance and proper patterning of organ initiation. PttKN1 gene, isolated from the vascular cambium of hybrid aspen (Populus tremula × P. tremuloides), is a member of class I KNOX gene family. In order to understand the roles of PttKN1 gene in meristem activity and morphogenesis as well as to explore the possibility to generate novel ornamental lines via its ectopic expression, it was introduced into the genome of Begonia maculata Raddi by Agrobacterium tumefasciens-mediated gene transformation here. Four types of transgenic plants were observed, namely coral-like (CL) type, ectopic foliole (EF) type, phyllotaxy-irregular (IP) type and cup-shaped (CS) type, which were remarkably different from corresponding wild type and were not also observed in the regenerated plantlets of wild type plant. Among these four types of transgenic plants, the phenotype of coral-like was observed for the first time in the transformants ectopically expressed KNOX genes. The observation of scanning electron microscope (SEM) showed ectopic meristems on the adaxial leaf surface of the transformants. Interestingly, the plantlets with ectopic foliole could generate new ectopic folioles from the original ectopic folioles again, and the plants regenerated from the EF-type transformants could also maintain the original morphology. The same specific RT-PCR band of the four types of transgenic plantlets showed that PttKN1 was ectopically expressed. All these data demonstrated that the ectopic expression of PttKN1 caused a series of alterations in morphology which provided possibilities producing novel ornamental lines and thatPttKN1 played important roles in meristem initiation, maintenance and organogenesis events as other class I KNOX genes.

Over-expression of the Hybrid Aspen Homeobox <i>PttKN1</i> Gene in Red Leaf Beet Induced Altered Coloration of Leaves

“…These phenotypes were mainly focused on the ectopic meristem formation, altered stem morphology and altered leaf morphology such as lobed leaf, distorted leaf etc. These morphological modifications were in highly accordance with other PttKN1 transformants (Hu et al, 2005;Xu et al, 2011). Besides these typical phenotypes, the transgenic PttKN1beet plant displayed changed color throughout the entire plant from claret of wild type to yellowish green.…”

“…The pigment concentration was calculated using extinction value E (1 cm/1%) al., 2014) produced various morphological alterations compared with their wild type plant. Those phenotypes were mainly focused on altered leaf arrangement (Hu et al, 2005;Meng et al, 2009b;Xu et al, 2011) and leaf morphology like lobed leaf (Hu et al, 2005;Xu et al, 2011;Xu et al, 2014), cup-shaped leaf (Xu et al, 2011) and distorted leaf (Hu et al, 2005;Meng et al, 2009a;Xu et al, 2011;Xu et al, 2014) etc. However, transgenic PttKN1 P. hybrida showed color modification of flower (Hu et al, 2005) and B. maculata showed color modification of leaf (Xu et al, 2011).…”

“…PttKN1 (Populus tremula × tremuloides KNOTTED1), which is a hybrid aspen homeobox gene (Hu et al, 2005;Meng et al, 2009a) plays an important role in plant development, especially in meristem initiation, maintenance and organogenesis (Xu et al. 2011).…”

“…2011). It is well reported that the PttKN1 transformants of Begonia maculata (Xu et al, 2011), carnation (Meng et al, 2009a), cockscomb (Meng et al, 2009b), Petunia hybrida (Hu et al, 2005) and tobacco (Xu et PCR assay DNA was extracted from the leaves of wild type and putative transgenic plants by improved CTAB method (Doyle, 1990). Transgenic plants were verified via PCR of the PttKN1 gene, NPTII gene and 35S-Promoter.…”

Genomic Resources for Evolutionary Studies in the Large, Diverse, Tropical Genus, Begonia

“…Begonia is also a major horticultural crop, being important in both bedding plants and indoor plants markets (Hvoslef-Eide and Munster 2007) and consequently large, accessible collections of species and hybrids are available (Tebbit 2005). Additionally, methods of in-vitro propagation and genetic transformation that have been developed for commercial exploitation of Begonia can also be applied to research (Kishimoto et al 2002;Xu et al 2011).…”