High frequency wheat regeneration from leaf tissue explants of regenerated plantlets

The specificities of tissue culture of wheat greatly limit the use of chloroplast transformation technologies in this crop. One limitation in wheat tissue culture is that it is difficult to regenerate plantlets from leaf tissue explants of regenerated plantlets, resulting in difficulty in obtaining homoplastic plants via multiple rounds of antibiotic selection of chloroplast transformants. Thus, a repeated in vitro regeneration system from leaf tissues was studied in this research. Our results showed that 2 mm leaf basal segments of the 4 cm high leaves from regenerated plantlets can give the best callus induction at present study. The best callus induction medium was Murashige and Skoog (MS) basal medium supplemented with 2 mg/L 2,4-dichlorophenoxyacetic acid and 1 mg/L naphthalenacetic acid, which gave a callus induction rate of up to 87.2%. The optimal differentiation medium was MS basal medium supplemented with 10 mg/L silver nitrate and 1 mg/L 2,3,5-triiodobenzoic acid, which gave a regeneration rate up to 33.7% for the wheat lines tested. This is the first report showing that leaf basal segments of in vitro regenerated plantlets can be used for regeneration of wheat. The establishment of a repetitive regeneration system should pave the way for the development of chloroplast transformation and the plant regeneration systems starting from leaf material of in vitro regenerated wheat and other cereal crops.

Protein post-translational modifications in auxin signaling

Protein post-translational modifications(PTMs),such as ubiquitination,phosphorylation,and small ubiquitin-like modifier(SUMO)ylation,are crucial for regulating protein stability,activity,subcellular localization,and binding with cofactors.Such modifications remarkably increase the variety and complexity of proteomes,which are essential for regulating numerous cellular and physiological processes.The regulation of auxin signaling is finely tuned in time and space to guide various plant growth and development.Accumulating evidence indicates that PTMs play critical roles in auxin signaling regulations.Thus,a thorough and systematic review of the functions of PTMs in auxin signal transduction will improve our profound comprehension of the regulation mechanism of auxin signaling and auxin-mediated various processes.This review discusses the progress of protein ubiquitination,phosphorylation,histone acetylation and methylation,SUMOylation,and S-nitrosylation in the regulation of auxin signaling.