Opportunities, Challenges, and Scientific Progress in Hemp Crops.

The resurgence of cannabis (Cannabis sativa L.) has been propelled by changes in the legal framework governing its cultivation and use, increased demand for hemp-derived products, and studies recognizing the industrial and health benefits of hemp. This has led to the creation of novel high-cannabidiol, low-Δ9-tetrahydrocannabinol varieties, enabling hemp crop expansion worldwide. This review elucidates the recent implications for hemp cultivation in Europe, with a focus on the legislative impacts on the cultivation practices, prospective breeding efforts, and dynamic scientific landscape surrounding this crop. We also review the current cultivars' cannabinoid composition of the European hemp market and its major differences with that of the United States.

Suppression of pyrrolidine ring biosynthesis and its effects on gene expression and subsequent accumulation of anatabine in leaves of tobacco (N. tabacum L.).

BACKGROUND: Anatabine, although being one of four major tobacco alkaloids, is never accumulated in high quantity in any of the naturally occurring species from the Nicotiana genus. Previous studies therefore focused on transgenic approaches to synthetize anatabine, most notably by generating transgenic lines with suppressed putrescine methyltransferase (PMT) activity. This led to promising results, but the global gene expression of plants with such distinct metabolism has not been analyzed. In the current study, we describe how these plants respond to topping and the downstream effects on alkaloid biosynthesis. RESULTS: The surge in anatabine accumulation in PMT transgenic lines after topping treatment and its effects on gene expression changes were analyzed. The results revealed increases in expression of isoflavone reductase-like (A622) and berberine bridge-like enzymes (BBLs) oxidoreductase genes, previously shown to be crucial for the final steps of nicotine biosynthesis. We also observed significantly higher methylputrescine oxidase (MPO) expression in all plants subjected to topping treatment. In order to investigate if MPO suppression would have the same effects as that of PMT, we generated transgenic plants. These plants with suppressed MPO expression showed an almost complete drop in leaf nicotine content, whereas leaf anatabine was observed to increase by a factor of ~ 1.6X. CONCLUSION: Our results are the first concrete evidence that suppression of MPO leads to decreased nicotine in favor of anatabine in tobacco roots and that this anatabine is successfully transported to tobacco leaves. Alkaloid transport in plants remains to be investigated to higher detail due to high variation of its efficiency among Nicotiana species and varieties of tobacco. Our research adds important step to better understand pyrrolidine ring biosynthesis and its effects on gene expression and subsequent accumulation of anatabine.

Cytosolic glutamine synthetase is important for photosynthetic efficiency and water use efficiency in potato as revealed by high-throughput sequencing QTL analysis.

KEY MESSAGE: WUE phenotyping and subsequent QTL analysis revealed cytosolic GS genes importance for limiting N loss due to photorespiration under well-watered and well-fertilized conditions. Potato (Solanum tuberosum L.) closes its stomata at relatively low soil water deficits frequently encountered in normal field conditions resulting in unnecessary annual yield losses and extensive use of artificial irrigation. Therefore, unraveling the genetics underpinning variation in water use efficiency (WUE) of potato is important, but has been limited by technical difficulties in assessing the trait on individual plants and thus is poorly understood. In this study, a mapping population of potatoes has been robustly phenotyped, and considerable variation in WUE under well-watered conditions was observed. Two extreme WUE bulks of clones were identified and pools of genomic DNA from them as well as the parents were sequenced and mapped to reference potato genome. Following a novel data analysis approach, two highly resolved QTLs were found on chromosome 1 and 9. Interestingly, three genes encoding isoforms of cytosolic glutamine synthase were located in the QTL at chromosome 1 suggesting a major contribution of this enzyme to photosynthetic efficiency and thus WUE in potato. Indeed, Glutamine synthetase enzyme activity of leaf extracts was measured and found to be correlated with contrasting WUE phenotypes.

Alkaloid chemophenetics and transcriptomics of the Nicotiana genus.

In this study, we determined the pyridine alkaloid content (nicotine, nornicotine, anabasine, anatabine, cotinine, and myosmine) of 58 species and 2 subspecies of the Nicotiana genus by ultra-high-performance liquid chromatography coupled with mass spectrometry. We observed clear correlation between Noctiflorae and Suaveolentes sections and their above average accumulation of anabasine in the genus. In addition, the results demonstrated the presence of not only trace amounts but quantifiable levels of myosmine, an alkaloid previously detected in only minute quantities, in the leaves and roots of 16 species. In this study, analysis of gene expression of 58 species and 2 subspecies from the Nicotiana genus by mRNA sequencing was performed for the first time. Sequencing reads were mapped against annotated genes of a Nicotiana tabacum reference genome and expression values were subsequently calculated. Hierarchical clustering of alkaloid biosynthesis pathway genes and alkaloid content composition revealed patterns clearly segregating Nicotiana sections. Correlation of gene expression with alkaloid accumulation phenotypes was evident, including low putrescine methyltransferase expression for all species in the Suaveolentes section or clear correlation of nicotine demethylase with conversion rates of nicotine to nornicotine in the majority of species. Multiple additional correlations between alkaloid accumulation and gene expression values were identified, which makes this study an important fundament toward future scientific exploration of the Nicotiana genus.

Transcriptome analysis suggests that starch synthesis may proceed via multiple metabolic routes in high yielding potato cultivars.

BACKGROUND: Glucose-6-phosphate is imported into the amyloplast of potato tubers and thought to constitute the precursor for starch synthesis in potato tubers. However, recently it was shown that glucose-1-phosphate can also be imported into the amyloplast and incorporated into starch via an ATP independent mechanism under special conditions. Nonetheless, glucose-6-phosphate is believed to be the quantitatively important precursor for starch synthesis in potato. PRINCIPAL FINDING: Potato tubers of the high yielding cv Kuras had low gene expression of plastidial phophoglucomutase (PGM) and normal levels of transcripts for other enzymes involved in starch metabolism in comparison with medium and low yielding cultivars as determined by DeepSAGE transcriptome profiling. The decrease in PGM activity in Kuras was confirmed by measuring the enzyme activity from potato tuber extracts. Contrary to expectations, this combination lead to a higher level of intracellular glucose-1-phosphate (G1P) in Kuras suggesting that G1P is directly imported into plastids and can be quantitatively important for starch synthesis under normal conditions in high yielding cultivars. SIGNIFICANCE: This could open entirely new possibilities for metabolic engineering of the starch metabolism in potato via the so far uncharacterized G1P transporter. The perspectives are to increase yield and space efficiency of this important crop. In the light of the increasing demands imposed on agriculture to support a growing global population this presents an exciting new possibility.