Functional genomics of cell elongation in developing cotton fibers.
Cotton fibers are single-celled seed trichomes of major economic importance. Factors that regulate the rate and duration of cell expansion control fiber morphology and important agronomic traits. For genetic characterization of rapid cell elongation in cotton fibers, approximately 14,000 unique genes were assembled from 46,603 expressed sequence tags (ESTs) from developmentally staged fiber cDNAs of a cultivated diploid species ( Gossypium arboreum L.). Conservatively, the fiber transcriptome represents 35-40% of the genes in the cotton genome. In silico expression analysis revealed that rapidly elongating fiber cells exhibit significant metabolic activity, with the bulk of gene transcripts, represented by three major functional groups - cell wall structure and biogenesis, the cytoskeleton and energy/carbohydrate metabolism. Oligonucleotide microarrays revealed dynamic changes in gene expression between primary and secondary cell wall biogenesis showing that fiber genes in the dbEST are highly stage-specific for cell expansion - a conclusion supported by the absence of known secondary cell wall-specific genes from our fiber dbEST. During the developmental switch from primary to secondary cell wall syntheses, 2553 "expansion-associated" fiber genes are significantly down regulated. Genes (81) significantly up-regulated during secondary cell wall synthesis are involved in cell wall biogenesis and energy/carbohydrate metabolism, which is consistent with the stage of cellulose synthesis during secondary cell wall modification in developing fibers. This work provides the first in-depth view of the genetic complexity of the transcriptome of an expanding cell, and lays the groundwork for studying fundamental biological processes in plant biology with applications in agricultural biotechnology.
Arpat
A Bulak
AB
Department of Agronomy and Range Science, University of California, One Shields Ave., CA, USA.
Waugh
Mark
M
Sullivan
John P
JP
Gonzales
Michael
M
Frisch
David
D
Main
Dorrie
D
Wood
Todd
T
Leslie
Anna
A
Wing
Rod A
RA
Wilkins
Thea A
TA
D048708:Cell Growth Processes / Q000235:genetics*; D002473:Cell Wall / Q000378:metabolism; D032561:Cotton Fiber; D020224:Expressed Sequence Tags; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D023281:Genomics / Q000379:methods*; D003368:Gossypium / Q000166:cytology / Q000235:genetics* / Q000254:growth & development; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic / Q000235:genetics
D010940:Plant Proteins