Cysteine protease gene expression and proteolytic activity during senescence of Alstroemeria petals.
The functional life of the flower is terminated by senescence and/or abscission. Multiple processes contribute to produce the visible signs of petal wilting and inrolling that typify senescence, but one of the most important is that of protein degradation and remobilization. This is mediated in many species through protein ubiquitination and the action of specific protease enzymes. This paper reports the changes in protein and protease activity during development and senescence of Alstroemeria flowers, a Liliaceous species that shows very little sensitivity to ethylene during senescence and which shows perianth abscission 8-10 d after flower opening. Partial cDNAs of ubiquitin (ALSUQ1) and a putative cysteine protease (ALSCYP1) were cloned from Alstroemeria using degenerate PCR primers and the expression pattern of these genes was determined semi-quantitatively by RT-PCR. While the levels of ALSUQ1 only fluctuated slightly during floral development and senescence, there was a dramatic increase in the expression of ALSCYP1 indicating that this gene may encode an important enzyme for the proteolytic process in this species. Three papain class cysteine protease enzymes showing different patterns of activity during flower development were identified on zymograms, one of which showed a similar expression pattern to the cysteine protease cDNA.
Wagstaff
Carol
C
Cardiff School of Biosciences, Main Building, Cardiff University, PO Box 915, Cardiff CF10 3TL, UK.
Leverentz
Michael K
MK
Griffiths
Gareth
G
Thomas
Brian
B
Chanasut
Usawadee
U
Stead
Anthony D
AD
Rogers
Hilary J
HJ
D000595:Amino Acid Sequence; D003001:Cloning, Molecular; D003546:Cysteine Endopeptidases / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D018076:DNA, Complementary / Q000235:genetics; D018507:Gene Expression Regulation, Developmental; D015971:Gene Expression Regulation, Enzymologic; D019668:Liliaceae / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D008969:Molecular Sequence Data; D010206:Papain / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D018547:Plant Stems / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016415:Sequence Alignment; D025801:Ubiquitin / Q000235:genetics / Q000378:metabolism*
D018076:DNA, Complementary; D010940:Plant Proteins; D025801:Ubiquitin; D003546:Cysteine Endopeptidases; D010206:Papain