Genome-wide identification,characterization,and expression analysis of aluminum-activated malate transporter genes(ALMTs)in Gossypium hirsutum L.

Aluminum-activated malate transporters(ALMT)are widely involved in plant growth and metabolic processes,including adaptation to acid soils,guard cell regulation,anion homeostasis,and seed development.Although ALMT genes have been identified in Arabidopsis,wheat,barley,and Lotus japonicus,little is known about its presence in Gossypium hirsutum L.In this study,ALMT gene recognition in diploid and tetraploid cotton were done using bioinformatics analysis that examined correlation between homology and evolution.Differentially regulated ALMT genetic profile in G.hirsutum was examined,using RNA sequencing and qRT-PCR,during six fiber developmental time-points,namely 5 d,7 d,10 d,15 d,20 d,and 25 d.We detected 36 ALMT genes in G.hirsutum,which were subsequently annotated and divided into seven sub-categories.Among these ALMT genes,34 had uneven distribution across 14/26 chromosomes.Conserved domains and gene structure analysis indicated that ALMT genes were highly conserved and composed of exons and introns.The GhALMT gene expression profile at different DPA(days post anthesis)in different varieties of G.hirsutum is indicative of a crucial role of ALMT genes in fiber development in G.hirsutum.This study provides basis for advancements in the cloning and functional enhancements of ALMT genes in enhancing fiber development and augmenting high quality crop production.

Transcriptional landscape of cotton roots in response to salt stress at single-cell resolution

Increasing soil salinization has led to severe reductions in plant yield and quality,and investigating the mo-lecular mechanism of salt stress response is therefore an urgent priority.In this study,we systematically analyzed the response of cotton roots to salt stress using single-cell transcriptomics technology;56281 high-quality cells were obtained from 5-day-old lateral root tips of Gossypium arboreum under natural growth conditions and different salt treatments.Ten cell types with an array of novel marker genes were identified and confirmed by in situ RNA hybridization,and pseudotime analysis of some specific cell types revealed their potential differentiation trajectories.Prominent changes in cell numbers under salt stress were observed for outer epidermal and inner endodermal cells,which were significantly enriched in response to stress,amide biosynthetic process,glutathione metabolism,and glycolysis/gluconeogenesis.Analysis of differentially expressed genes identified in multiple comparisons revealed other functional ag-gregations concentrated on plant-type primary cell wall biogenesis,defense response,phenylpropanoid biosynthesis,and metabolic pathways.Some candidate differentially expressed genes encoding transcrip-tion factors or associated with plant hormones also responsive to salt stress were identified,and the func-tion of Ga03G2153,annotated as auxin-responsive GH3.6,was confirmed by virus-induced gene silencing.The GaGH3.6-silenced plants showed a severe stress-susceptible phenotype,and physiological and biochemical measurements indicated that they suffered more significant oxidative damage.These results suggest that GaGH3.6 might participate in cotton salt tolerance by regulating redox processes.We thus construct a transcriptional atlas of salt-stressed cotton roots at single-cell resolution,enabling us to explore cellular heterogeneity and differentiation trajectories and providing valuable insights into the mo-lecular mechanisms that underlie plant stress tolerance.

Widespread incomplete lineage sorting and introgression shaped adaptive radiation in the Gossypium genus

Cotton(Gossypium)stands as a crucial economic crop,serving as the primary source of naturalfiber for the textile sector.However,the evolutionary mechanisms driving speciation within the Gossypium genus remain unresolved.In this investigation,we leveraged 25 Gossypium genomes and introduced four novel assem-blies—G.harknessii,G.gossypioides,G.trilobum,and G.klotzschianum(Gklo)—to delve into the speciation history of this genus.Notably,we encountered intricate phylogenies potentially stemming from introgres-sion.These complexities are further compounded by incomplete lineage sorting(ILS),a factor likely to have been instrumental in shaping the swift diversification of cotton.Our focus subsequently shifted to the rapid radiation episode during a concise period in Gossypium evolution.For a recently diverged lineage comprising G.davidsonii,Gklo,and G.raimondii,we constructed afinely detailed ILS map.Intriguingly,this analysis revealed the non-random distribution of ILS regions across the reference Gklo genome.Moreover,we identified signs of robust natural selection influencing specific ILS regions.Noteworthy variations per-taining to speciation emerged between the closely related sister species Gklo and G.davidsonii.Approxi-mately 15.74%of speciation structural variation genes and 12.04%of speciation-associated genes were esti-mated to intersect with ILS signatures.Thesefindings enrich our understanding of the role of ILS in adaptive radiation,shedding fresh light on the intricate speciation history of the Gossypium genus.