Transcriptional Controls for Early Bolting and Flowering in Angelica sinensis

The root of the perennial herb Angelica sinensis is a widely used source for traditional Chinese medicines. While the plant thrives in cool-moist regions of western China, early bolting and flowering (EBF) for young plants significantly reduces root quality and yield. Approaches to inhibit EBF by changes in physiology during the vernalization process have been investigated; however, the mechanism for activating EBF is still limited. Here, transcript profiles for bolted and unbolted plants (BP and UBP, respectively) were compared by transcriptomic analysis, expression levels of candidate genes were validated by qRT-PCR, and the accumulations of gibberellins (GA₁, GA₄, GA₈, GA₉ and GA₂₀) were also monitored by HPLC-MS/MS. A total of over 72,000 unigenes were detected with ca. 2600 differentially expressed genes (DEGs) observed in the BP compared with UBP. While various signaling pathways participate in flower induction, it is genes associated with floral development and the sucrose pathway that are observed to be coordinated in EBF plants, coherently up- and down-regulating flowering genes that activate and inhibit flowering, respectively. The signature transcripts pattern for the developmental pathways that drive flowering provides insight into the molecular signals that activate plant EBF.

Metabolic Changes of Amino Acids and Flavonoids in Tea Plants in Response to Inorganic Phosphate Limitation

The qualities of tea (Camellia sinensis) are not clearly understood in terms of integrated leading molecular regulatory network mechanisms behind inorganic phosphate (Pi) limitation. Thus, the present work aims to elucidate transcription factor-dependent responses of quality-related metabolites and the expression of genes to phosphate (P) starvation. The tea plant organs were subjected to metabolomics analysis by GC×GC-TOF/MS and UPLC-Q-TOF/MS along with transcription factors and 13 metabolic genes by qRT-PCR. We found P starvation upregulated SPX2 and the change response of Pi is highly dependent on young shoots. This led to increased change in abundance of carbohydrates (fructose and glucose), amino acids in leaves (threonine and methionine), and root (phenylalanine, alanine, tryptophan, and tyrosine). Flavonoids and their glycosides accumulated in leaves and root exposed to P limitation was consistent with the upregulated expression of anthocyanidin reductase (EC 1.3.1.77), leucoanthocyanidin dioxygenase (EC 1.4.11.19) and glycosyltransferases (UGT78D1, UGT78D2 and UGT57L12). Despite the similar kinetics and high correlation response of Pi and SPX2 in young shoots, predominating theanine and other amino acids (serine, threonine, glutamate, valine, methionine, phenylalanine) and catechin (EGC, EGCG and CG) content displayed opposite changes in response to Pi limitation between Fengqing and Longjing-43 tea cultivars.

ATP-sulfurylase, sulfur-compounds, and plant stress tolerance

Sulfur (S) stands fourth in the list of major plant nutrients after N, P, and K. Sulfate (SO4 (2-)), a form of soil-S taken up by plant roots is metabolically inert. As the first committed step of S-assimilation, ATP-sulfurylase (ATP-S) catalyzes SO4 (2-)-activation and yields activated high-energy compound adenosine-5(')-phosphosulfate that is reduced to sulfide (S(2-)) and incorporated into cysteine (Cys). In turn, Cys acts as a precursor or donor of reduced S for a range of S-compounds such as methionine (Met), glutathione (GSH), homo-GSH (h-GSH), and phytochelatins (PCs). Among S-compounds, GSH, h-GSH, and PCs are known for their involvement in plant tolerance to varied abiotic stresses, Cys is a major component of GSH, h-GSH, and PCs; whereas, several key stress-metabolites such as ethylene, are controlled by Met through its first metabolite S-adenosylmethionine. With the major aim of briefly highlighting S-compound-mediated role of ATP-S in plant stress tolerance, this paper: (a) overviews ATP-S structure/chemistry and occurrence, (b) appraises recent literature available on ATP-S roles and regulations, and underlying mechanisms in plant abiotic and biotic stress tolerance, (c) summarizes ATP-S-intrinsic regulation by major S-compounds, and (d) highlights major open-questions in the present context. Future research in the current direction can be devised based on the discussion outcomes.

In vitro organogenesis secondary metabolite production and heavy metal analysis in Swertia chirayita

An efficient protocol of plant regeneration through direct and indirect organogenesis in Swertia chirayita was developed. Explants cultured on Murashige and Skoog medium supplemented with 2,4-D (0.5 mg L−1) with combination of Kinetin (0.5 mg L−1) showed the highest frequency (84%) of callusing and 1.0mg L−1 6-benzyladenine (BA) in combination with (100 mg L−1) Adenine sulphate (Ads) + (0.1 mg L−1) Indole acetic acid (IAA) was excellent for maximum adventitious shoot (12.69 ± 1.30) formation in four week of culture. A maximum number of (7.14 ± 0.99) shoots were developed per leaf explants through direct organogenesis. The highest frequency of rooting (11.46 ± 1.56) was observed on MS medium augmented with IAA (1.0 mg L−1). Well-rooted shoots transferred to plastic pots containing a soilrite: sand mix and then moved to the greenhouse for further growth and development. Four major secondary metabolites were analyzed and quantified using high performance liquid chromatography. Amount of secondary metabolites was found significantly higher, in in vitro plantlets compared to in vivo plantlets and callus raised from S. chirayita. Higher heavy metal accumulation in in vitro as compared to in vivo plantlets correlates higher secondary metabolite production supporting that they play regulatory role in influencing the plant secondary metabolism.