Alternative transcript initiation and novel post-transcriptional processing of a leucine-rich repeat receptor-like protein kinase gene that responds to short-day photoperiodic floral induction in morning glory (Ipomoea nil).
A gene (inrpk1) encoding a putative receptor-like protein kinase was isolated from the Japanese morning glory, Ipo-moea (Pharbitis) nil Roth. cv. Violet. The receptor-like portion of the largest derived polypeptide contains 26 direct leucine-rich repeats (LRRs) in a single block, and the catalytic portion has all the conserved amino acid residues characteristic of Ser/Thr protein kinases. RNA blot analysis detected multiple transcripts in cotyledons. The largest (4.4 kb) transcript encodes the predicted full length polypeptide (INRPK1), whereas a 1.6 kb transcript apparently originates from a secondary transcription initiation site within the gene and potentially encodes a protein kinase identical to INRPK1 but lacking most of the LRRs. Two transcripts (ca. 2.7 and 2.6 kb) are created by alternative 3'-splicing of a large (ca. 1.4-1.5 kb) cryptic intron in the LRR region, creating one transcript (2.6 kb) potentially encoding a small, secretable polypeptide. The larger transcript encoding a polypeptide identical to INRPK1, but lacking 21 LRRs, predominates in vegetative roots. Competitive PCR indicates that inrpk1 mRNA increases 20-fold in cotyledons in response to a previously given single floral-inducing short-day (SD). No differences of this magnitude were detected in any other organs examined from plants similarly treated. This pattern of expression and differential processing suggests a role for inrpk1 in some aspect of SD photoperiodic-induced flowering in morning glory.
Bassett
C L
CL
USDA, ARS, Appalachian Fruit Research Station, Kearneysville, WV 25430, USA. cbassett@afrs.ars.usda.gov
Nickerson
M L
ML
Cohen
R A
RA
Rajeevan
M S
MS
D017398:Alternative Splicing; D000595:Amino Acid Sequence; D001483:Base Sequence; D015139:Blotting, Southern; D018744:DNA, Plant / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification; D018628:Gene Dosage; D018507:Gene Expression Regulation, Developmental / Q000528:radiation effects; D015971:Gene Expression Regulation, Enzymologic / Q000528:radiation effects; D018506:Gene Expression Regulation, Plant / Q000528:radiation effects; D017343:Genes, Plant / Q000235:genetics; D008969:Molecular Sequence Data; D017440:Photoperiod; D063245:Plant Development; D010940:Plant Proteins / Q000235:genetics*; D010944:Plants / Q000235:genetics*; D017346:Protein Serine-Threonine Kinases; D012323:RNA Processing, Post-Transcriptional; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics*; D017422:Sequence Analysis, DNA; D014018:Tissue Distribution; D014158:Transcription, Genetic
D018744:DNA, Plant; D010940:Plant Proteins; D012333:RNA, Messenger; D020794:Receptor Protein-Tyrosine Kinases; D017346:Protein Serine-Threonine Kinases; C412427:inrpk1 protein, Ipomoea nil