Polysaccharide composition during cotton seed fibre development:temporal differences between species and in different seasons

Background:Cotton seed fibres are long single-celled epidermal trichomes that first appear on the surface of the ovule at anthesis and then elongate rapidly over a period of 15-25 days until a secondary cell wall(SCW)begins to develop through a rapid increase in the deposition of microfibrillar cellulose between the plasma membrane and the primary cell wall that eventually terminates elongation.Quantitative measurements of the different polysaccharide components in both wall types over time and how they influence fibre quality can direct studies involved in enhanc-ing fibre properties for yarn quality through cell wall manipulation or molecular breeding.Results:A detailed chemical analysis of cell wall composition by differential solvent fractionation was used to identify the range of polysaccharides present in mature cotton fibres and used to validate a simpler total cell wall monosaccharide linkage analysis protocol for wall compositional analysis.Analysis of fibres from 5 days post-anthesis through maturity for three cultivated species,Gossypium hirsutum,G.barbadense,and G.arboreum,showed the dynamic nature of cell wall polysaccharide composition through fibre development and that it progressed differently for each species.Plants grown in the glasshouse during either autumn to winter or spring to summer and within each species had fibre qualities and temporal aspects of cell wall development that were different for each season.Notably,the timing of the deposition of the SCW was delayed in winter grown plants and appeared to influence key fibre qual-ity properties.Conclusions:These results suggest that the temporal aspects of cell wall polysaccharide biogenesis during fibre development influence final fibre quality,and this timing is determined by both genetic and environmental factors.The onset of SCW synthesis appears to be a critical factor coinciding with termination of fibre elongation and specify-ing the duration of wall thickening that then affects fibre length and other wall-associated quality parameters that ultimately determine yarn quality.

scCloudMine:A cloud-based app for visualization,comparison,and exploration of single-cell transcriptomic data

scCloudMine is a cloud-based application for visualization,comparison,and exploration of single-cell transcriptome data.It does not require an on-site,high-power computing server,installation,or associated expertise and expense.Users upload their own or publicly available scRNA-seq datasets after preprocessing for visualization using a web browser.The data can be viewed in two color modes—Cluster,representing cell identity,and Values,showing levels of expression—and data can be queried using keywords or gene identification number(s).Using the app to compare studies,we determined that some genes frequently used as cell-type markers are in fact study specific.The apparent cell-specific expression of PHO1;H3 differed between GFP-tagging and scRNA-seq studies.Some phosphate transporter genes were induced by protoplasting,but they retained cell specificity,suggesting that cell-specific responses to stress(i.e.,protoplasting)can occur.Examination of the cell specificity of hormone response genes revealed that 132 hormone-responsive genes display restricted expression and that the jasmonate response gene TIFY8 is expressed in endodermal cells,in contrast to previous reports.It also appears that JAZ repressors have cell-type-specific functions.These features identified using scCloudMine highlight the need for resources to enable biological researchers to compare their datasets of interest under a variety of parameters.scCloudMine enables researchers to form new hypotheses and perform comparative studies and allows for the easy re-use of data from this emerging technology by a wide variety of users who may not have access or funding for high-performance on-site computing and support.

How sensing arsenite helps plants survive on toxic soils

Metals and metalloids are present in soils and ground water.They constitute both essential plant nutrients and potent poisons.Arsenic(As)is one of the most prevalent toxic compounds in soil with average concentrations between 5 and 7.5 mg kg 1 facing constant enrichment through anthropogenic activities,as well as soil weathering and volcanism Wenzel(2013).Both phosphorus(P)and As are non-metals found alongside nitrogen(N)in group 15 of the periodic table.

A Phytochrome B-PIF4-MYC2/MYC4 module inhibits secondary cell wall thickening in response to shaded light

Secondary cell walls(SCWs)in stem cells provide mechanical strength and structural support for growth.SCW thickening varies under different light conditions.Our previous study revealed that blue light enhances SCW thickening through the redundant function of MYC2 and MYC4 directed by CRYPTOCHROME1(CRY1)signaling in fiber cells of the Arabidopsis inflorescence stem.In this study,we find that the Arabidopsis PHYTOCHROME B mutant phyB displays thinner SCWs in stem fibers,but thicker SCWs are deposited in the PHYTOCHROME INTERACTING FACTOR(PIF)quadruple mutant pif1pif3pif4pif5(pifq).The shaded light condition with a low ratio of red to far-red light inhibits stem SCW thickening.PIF4 interacts with MYC2 and MYC4 to affect their localization in nuclei,and this interaction results in inhibition of the MYCs’transactivation activity on the NST1 promoter.Genetic evidence shows that regulation of SCW thickening by PIFs is dependent on MYC2/MYC4 function.Together,the results of this study reveal a PHYB-PIF4-MYC2/MYC4 module that inhibits SCW thickening in fiber cells of the Arabidopsis stem.