Characterization,efficient transformation and regeneration of Chirita pumila (Gesneriaceae), a potential evo-devo model plant

An efficient transformation and regeneration system is essential for functional investigation of developmental genes and related elements in the field of evolutionary developmental biology (evo-devo). Chirita pumila D. Don belongs to the Gesneriaceae family, one of the most basal groups in Lamiales sensu lato, and possesses many tractable biological features including annual habit, small plant size, short generation time, abundant offspring and low chromosome number. In addition, C. pumila has cleistogamous flowers with potential cross-pollination, a special phenomenon first reported herein in Gesneriaceae. Parameters affecting shoot induction and genetic transformation have been evaluated, including plant growth regulators, temperature, antibiotic concentration, pre- and co-culture duration, Agrobacterium cell density and infection time. Polymerase chain reaction and β-Glucuronidase (GUS) activity assays of T0 and T1 plants show that the GUS gene has been introduced into the host with stable and universal expression. The applicability of the transformation system in gene function investigation is further confirmed by transforming a GsNST1B gene from Glycine soja. This transformation system provides a valuable platform for deep function analyses of related genes and elements for a wide range of evo-devo studies, especially in the field of floral evolution, which would develop its potential of being a model organism in Lamiales s. l.