Functional analysis of the teosinte branched 1 gene in the tetraploid switchgrass (Panicum virgatum L.) by CRISPR/Cas9-directed mutagenesis

Tillering is an important biomass yield component trait in switchgrass (Panicum virgatum L.). Teosinte branched 1 (tb1)/Branched 1 (BRC1) gene is a known regulator for tillering/branching in several plant species; however, its role on tillering in switchgrass remains unknown. Here, we report physiological and molecular characterization of mutants created by CRISPR/Cas9. We successfully obtained non-chimeric Pvtb1a and Pvtb1b mutants from chimeric T0 mutants using nodal culture. The biallelic Pvtb1a-Pvtb1b mutant plants produced significantly more tillers and higher fresh weight biomass than the wild-type plants. The increased tiller production in the mutant plants resulted primarily from hastened outgrowth of lower axillary buds. Increased tillers were also observed in transgene-free T1 monoallelic mutants for either Pvtb1a-Pvtb1b or Pvtb1b gene alone, suggesting Pvtb1 genes act in a dosage-dependent manner. Transcriptome analysis showed 831 genes were differentially expressed in the Pvtb1a-Pvtb1b double knockdown mutant. Gene Ontology analysis revealed downregulation of Pvtb1 genes affected multiple biological processes, including transcription, flower development, cell differentiation, and stress/defense responses in edited plants. This study demonstrates that Pvtb1 genes play a pivotal role in tiller production as a negative regulator in switchgrass and provides opportunities for further research aiming to elucidate the molecular pathway regulating tillering in switchgrass.HighlightSolid non-chimeric mutants were successfully isolated from CRISPR/Cas9-induced chimeric mutants using nodal culture. Teosinte branched 1 (tb1) genes are involved in various pathways to regulate tillering in switchgrass.

Micropropagation, genetic fidelity assessment and phytochemical studies of Clerodendrum thomsoniae Balf. f. with special reference to its anti-stress properties

Clerodendrum thomsoniae commonly known as bleeding heart vine or bag flower which is a good candidate for a new crop for the floriculture industry. In this study, in-vitro callus regeneration of C. thomsoniae through nodal culture has been attempted. Murashige and Skoog’s medium supplemented with 2 mg/l BAP and 0.5 mg/l

An Improved Plant Regeneration of Vanilla planifolia Andrews

Multiple shoots of Vanilla planifolia were induced from nodal explants under influence of different concentrations of plant growth regulators and coconut water (CW). A comparison of shoot regeneration between semi solid and liquid culture media was also investigated. Ninety seven per cent of the explants produced a mean number of 9.6 shoots with a mean shoot length of 4.70 cm when cultured on liquid MS supplemented with 1.0 mg/l BAP in combination of 15% CW. Shoots generated were rooted with frequency of 93% on MS supplemented with 1.0 mg/l NAA with a mean number of 2.9 roots per shoot and mean length of 4.0 cm within four weeks. The plantlets were transferred to sand : compost mixture (1 : 2) with 85.0% survival rate recorded after four weeks of acclimation. Key words: Regeneration, coconut water, nodal culture, vanilla D.O.I. 10.3329/ptcb.v21i1.9560 Plant Tissue Cult. & Biotech. 21(1): 27-33, 2011 (June)