Topping and grafting affect the alkaloid content and gene expression patterns of tobacco (Nicotiana tabacumL.)

Abstract

In this study, we aimed to determine molecular mechanisms underlying the effects of topping and grafting in tobacco ( Nicotiana tabacum L.) by comparing the alkaloid contents and enrichment pathways of differentially expressed genes (DEGs) among plants subjected to different combinations of topping and grafting treatments. Plants of the tobacco variety “Zhongyan 100” and eggplant ( Solanum melongena L.) were grafted in four combinations as scions and rootstocks, respectively. The four treatment groups were tobacco with topping, tobacco without topping, topped tobacco grafted onto an eggplant rootstock, and non‐topped tobacco grafted onto an eggplant rootstock. Tobacco leaves were collected on the day of topping, at 7 days after topping, and after flue curing, the alkaloid contents of the collected leaves were determined. Leaves of plants subjected to the different treatments were collected for RNA sequencing and screened for DEGs, which were subsequently subjected to functional enrichment analyses. Analyses revealed reductions in the leaf alkaloid contents of tobacco subjected to combined topping and eggplant grafting. Gene annotation indicated that topping influences biological processes such as starch metabolism and stress response, whereas grafting affected the biosynthesis and metabolic pathways of secondary metabolites. Downregulated DEGs between non‐topped tobacco and eggplant‐grafted topped tobacco and between topped and non‐topped tobacco are mainly involved in inositol phosphate metabolic and biosynthetic processes. Downregulated DEGs between different grafting methods (eggplant‐grafted non‐topped tobacco vs. non‐topped tobacco and eggplant‐grafted topped tobacco vs. topped tobacco) are mainly involved in sesquiterpene synthase activity and photosynthesis. The findings of this study provide important insights into the molecular mechanisms underlying the effects of topping and grafting on tobacco plants.

Transcriptomic analysis ofPicea abiestissue culture reveals the impact of culture conditions and the presence of glucuronoxylan on extracellular lignin production

“…Interestingly, the cells produced ECL in all cultivation flasks, at approximately the same time as it occurred for the “ECL-inducing” liquid medium used in previous work (13-20 days). 21…”

“…To address this, in a previous study we added a secondary cell wall hemicellulose, xylan, into the nutrient medium of solid and suspension tissue cultures and investigated its role on monolignol production and the final structure of ECL. 21 We concluded that cell growth and monolignol production are affected by the presence of xylan in the nutrient media, and that the structure of the ECL was affected as well, likely due to interactions with the xylan.…”

“…The composition of nutrient media is described elsewhere. 13, 14 As in previous work 21 , xylan was added into the solid and/or liquid nutrient medium in concentrations of 0.5 g/L and 1 g/L, before pH adjustment and autoclaving. In standard experiments, an “ECL non-inducing” medium is used for solid culture, and an “ECL-inducing” medium is used for suspension cultures.…”

“…As described in previous work, Norway spruce cells (Picea abies (L.) Karst., line A3/85) were maintained on solid medium and, when needed, transferred into liquid medium suspension cultures, in which monolignol secretion was induced. 14, 21 Every three weeks, the cells were subcultured to fresh solid medium. The transfer into suspension cultures was performed two weeks after a subculture.…”

Widely Targeted Metabolomic Analysis Provides New Insights into the Effect of Rootstocks on Citrus Fruit Quality

“…The differentially abundant metabolites of fruits, lipids and flavonoids in 'Gold Nugget'; flavonoids, alkaloids, lignans, and coumarins in 'Tango'; and flavonoids and phenolic acids in 'Orah' might explain the differences in taste and quality among the different rootstocks. In addition to affecting the taste of fruits, rootstocks can also regulate the biosynthesis of various compounds, such as amino acids [40], phenolic acids [41], alkaloids [42], and flavonoids [43], and improve plant tolerance to various stresses by regulating the biosynthesis of metabolic products. Rootstocks can affect the tolerance of citrus scions to pathogens by affecting primary and secondary metabolites [44], and can also improve the low-temperature resistance of bitter gourd by regulating sucrose and nitrogen metabolism [45].…”