Effects of Piriformospora indica on the Respiration of Taxus chinensis var.mairei under Water Stress

Seedlings of Taxus chinensis var.mairei were used as experimental materials to study the adaptation of Piriformospora indica to this plant under water stress.The materials were divided into two groups,namely,with or without inoculation with P.indica.Each group was subjected to four different levels of water stress.Vitality and physiological and biochemical indexes of the roots of T.chinensis var.mairei were regularly measured.Under water stress,T.chinensis var.mairei had significantly decreased root vitality;root vitality was higher in inoculated roots than in uninoculated roots.Under intense water stress,the inoculated roots had a higher soluble sugar content than the uninoculated roots.Under water stress,T.chinensis var.mairei experienced decreased activity of aerobic respiratory metabolic enzymes.The activity of anaerobic respiratory metabolic enzymes and alcohol dehydrogenase initially increased and then decreased,whereas that of lactate dehydrogenase increased.The inoculated roots had a higher activity of respiratory metabolic enzymes than the uninoculated roots.As water stress was further intensified,the roots had significantly decreased activity of aerobic respiratory metabolic enzymes and significantly increased activity of anaerobic respiratory metabolic enzymes.The activity of respiratory metabolic enzymes decreased faster in the uninoculated roots than in the inoculated roots.This study demonstrated that Piriformospora indica plays a positive role in enhancing the antihypoxic ability of T.chinensis var.mairei,thereby alleviating plant damage due to water stress.

Comparison of Morphological and Anatomical Characteristics of Taxus chinensis var.mairei Seedlings Root under Waterlogging Stress in Different Substrates

Four different ratios of river sand,ceramic pellets,vermiculite and perlite(1:1),and field soil were selected as the substrates in this experiment,and four gradient levels of root waterlogging,half waterlogging,full waterlogging and normal were set to investigate the effects of different gradients of waterlogging stress on the root morphology of Taxus chinensis var.mairei seedlings under different substrates.In this study,the root anatomical structure of Taxus chinensis var.mairei under different waterlogging stress was observed by the paraffin section method.The roots of T.chinensis var.mairei were diarch,with no pith and resin canals.There was a large number of tannins in the pericycle of the aerial adventitious roots of seedlings adapted to waterlogging.Also,the endodermis has obvious casparian strip thickening,and there were 4-5 layers of large parenchymatous cells in the close to the inner side of the pericycle in the vascular cylinder,which could increase the storage capacity,and transport capacity of the root.Under the treatment of root waterlogging stress,the development of plant roots in the mixed substrate of vermiculite and,perlite was the earliest.Under half waterlogging stress,T.chinensis var.mairei seedlings treated with various substrates all could better adapt to the environment of waterlogging stress.Under the stress of fully waterlogging,the roots of seedlings planted in river sand substrate developed secondary growth.

Microsatellite loci from Taxus chinensis var. mairei (Taxaceae), an endangered and economically important tree species in China

Taxus chinensis var.mairei is an endangered and economically important tree species in China.Four polymorphic microsatellite markers were developed and characterized using the fast isolation by amplified fragment length polymorphism(AFLP)of sequences containing repeats(FIASCO)protocol.Polymorphism of each locus was quantified for five natural populations from Hubei Province,China.The number of alleles per locus varied from 6 to 24.The ranges of observed and expected heterozygosity were 0.493–1.000 and 0.440–0.845,respectively.These are the first microsatellites reported for the family of Taxaceae and will be helpful for the ongoing population and conservation genetics research of Taxus chinensis var.mairei.

Mass spectrometry imaging and single-cell transcriptional profiling reveal the tissue-specific regulation of bioactive ingredient biosynthesis in Taxus leaves

Taxus leaves provide the raw industrial materials for taxol,a natural antineoplastic drug widely used in the treatment of various cancers.However,the precise distribution,biosynthesis,and transcriptional regulation of taxoids and other active components in Taxus leaves remain unknown.Matrix-assisted laser desorption/ionization–mass spectrometry imaging analysis was used to visualize various secondary metabolites in leaf sections of Taxus mairei,confirming the tissue-specific accumulation of different active metabolites.Single-cell sequencing was used to produce expression profiles of 8846 cells,with a median of 2352 genes per cell.Based on a series of cluster-specific markers,cells were grouped into 15 clusters,suggesting a high degree of cell heterogeneity in T.mairei leaves.Our data were used to create the first Taxus leaf metabolic single-cell atlas and to reveal spatial and temporal expression patterns of several secondary metabolic pathways.According to the cell-type annotation,most taxol biosynthesis genes are expressed mainly in leaf mesophyll cells;phenolic acid and flavonoid biosynthesis genes are highly expressed in leaf epidermal cells(including the stomatal complex and guard cells);and terpenoid and steroid biosynthesis genes are expressed specifically in leaf mesophyll cells.A number of novel and cell-specific transcription factors involved in secondary metabolite biosynthesis were identified,including MYB17,WRKY12,WRKY31,ERF13,GT_2,and bHLH46.Our research establishes the transcriptional landscape of major cell types in T.mairei leaves at a single-cell resolution and provides valuable resources for studying the basic principles of cell-type-specific regulation of secondary metabolism.