Arabidopsis CPR5 is a senescence-regulatory gene with pleiotropic functions as predicted by the evolutionary theory of senescence

Abstract

Evolutionary theories of senescence predict that genes with pleiotropic functions are important for senescence regulation. In plants there is no direct molecular genetic test for the existence of such senescence-regulatory genes. Arabidopsis cpr5 mutants exhibit multiple phenotypes including hypersensitivity to various signalling molecules, constitutive expression of pathogen-related genes, abnormal trichome development, spontaneous lesion formation, and accelerated leaf senescence. These indicate that CPR5 is a beneficial gene which controls multiple facets of the Arabidopsis life cycle. Ectopic expression of CPR5 restored all the mutant phenotypes. However, in transgenic plants with increased CPR5 transcripts, accelerated leaf senescence was observed in detached leaves and at late development around 50 d after germination, as illustrated by the earlier onset of senescence-associated physiological and molecular markers. Thus, CPR5 has early-life beneficial effects by repressing cell death and insuring normal plant development, but late-life deleterious effects by promoting developmental senescence. As such, CPR5 appears to function as a typical senescence-regulatory gene as predicted by the evolutionary theories of senescence.

Fusarium oxysporum hijacks COI1‐mediated jasmonate signaling to promote disease development in Arabidopsis

“…Further evidence for the importance of senescence programming in F. oxysporum susceptibility has come from the lesion mimic mutant cpr5 that has constitutive PDF1.2 expression, but also exhibits accelerated senescence (Bowling et al, 1997;Lorrain et al, 2003;Jing et al, 2007), and is highly susceptible to F. oxysporum . The premature senescence response in cpr5 is suggested to be a form of autophagic programmed cell death, an exaggerated form of autophagy characterized by slow cell death, and enhanced by JA signaling (Love et al, 2008).…”

“…A role for increased senescence in plant susceptibility to F. oxysporum was previously shown by Schenk et al (2005) in the early senescence mutant constitutive expresser of PR5 (cpr5) (Bowling et al, 1997;Jing et al, 2007). As jasmonate signaling is a known inducer of precocious leaf senescence, and coi1 is immune to this response (He et al, 2002;Wasternack, 2007), the coi1-mediated inhibition of symptom development and subsequent plant death may be, in part, a result of the inability of F. oxysporum to induce a host senescence response in this mutant.…”

TheArabidopsis onset of leaf death5Mutation of Quinolinate Synthase Affects Nicotinamide Adenine Dinucleotide Biosynthesis and Causes Early Ageing

“…That is especially visible in Arabidopsis, in which the onset of leaf senescence occurs in an age-dependent way (Gan and Amasino, 1997;Quirino et al, 2000;Jing et al, 2002). Moreover, the recent identification of genes that affect the onset of leaf senescence (Woo et al, 2001;Jing et al, 2005Jing et al, , 2007 reveals common mechanisms present in the regulation of ageing between plants and animals.…”

CPR5, a Jack of all trades in plants

“…1 We found that CPR5 is important for early plant growth but promotes senescence at late development and hence proposed it as a senescence-regulatory gene as predicted by the Evolutionary Theory of Senescence derived from studies on animal ageing. One of the key unsolved issues is how CPR5 contributes to the early plant growth and development.…”

“…2,3 Several more cpr5 alleles were subsequently identified in screens for mutants with altered trichome development, 4 dark induced senescence (hys1 alleles) 5 and ethyleneinduced senescence (old1 alleles). 1,6 So far, described alterations in cpr5 mutants include (1) enhanced constitutive expression of PR genes, (2) elevated salicylic acid and jasmonic acid levels, (3) hypersensitivities to sugar, ABA, ethylene and jasmonic acid, (4) accelerated leaf senescence, (5) spontaneous lesion mimic cell death, (6) defective cell proliferation, endoreduplication and trichome development, (7) reduced plant growth and reproduction fecundity. [1][2][3][4][5][6][7] Thus, cpr5 mutations possess pleiotropic phenotypes indicating that CPR5 is an essential-for-life gene in Arabidopsis.…”