Staying green postharvest: how three mutations in the Arabidopsis chlorophyll b reductase gene NYC1 delay degreening by distinct mechanisms.
Stresses such as energy deprivation, wounding and water-supply disruption often contribute to rapid deterioration of harvested tissues. To uncover the genetic regulation behind such stresses, a simple assessment system was used to detect senescence mutants in conjunction with two rapid mapping techniques to identify the causal mutations. To demonstrate the power of this approach, immature inflorescences of Arabidopsis plants that contained ethyl methanesulfonate-induced lesions were detached and screened for altered timing of dark-induced senescence. Numerous mutant lines displaying accelerated or delayed timing of senescence relative to wild type were discovered. The underlying mutations in three of these were identified using High Resolution Melting analysis to map to a chromosomal arm followed by a whole-genome sequencing-based mapping method, termed 'Needle in the K-Stack', to identify the causal lesions. All three mutations were single base pair changes and occurred in the same gene, NON-YELLOW COLORING1 (NYC1), a chlorophyll b reductase of the short-chain dehydrogenase/reductase (SDR) superfamily. This was consistent with the mutants preferentially retaining chlorophyll b, although substantial amounts of chlorophyll b were still lost. The single base pair mutations disrupted NYC1 function by three distinct mechanisms, one by producing a termination codon, the second by interfering with correct intron splicing and the third by replacing a highly conserved proline with a non-equivalent serine residue. This non-synonymous amino acid change, which occurred in the NADPH binding domain of NYC1, is the first example of such a mutation in an SDR protein inhibiting a physiological response in plants.
The New Zealand Institute for Plant & Food Research Limited, Private Bag 11600, Palmerston North 4442, New Zealand Institute of Fundamental Sciences, Massey University, Private Bag 11222, Palmerston North, New Zealand.
Rubina
R
Jibran
The New Zealand Institute for Plant & Food Research Limited, Private Bag 11600, Palmerston North 4442, New Zealand.
Kerry L
KL
Sullivan
The New Zealand Institute for Plant & Food Research Limited, Private Bag 92169, Auckland 1142, New Zealand.
Ross
R
Crowhurst
The New Zealand Institute for Plant & Food Research Limited, Private Bag 11600, Palmerston North 4442, New Zealand.
Zoe A
ZA
Erridge
The New Zealand Institute for Plant & Food Research Limited, Private Bag 11600, Palmerston North 4442, New Zealand.
David
D
Chagné
The New Zealand Institute for Plant & Food Research Limited, Private Bag 11600, Palmerston North 4442, New Zealand.
Andrew R G
AR
McLachlan
The New Zealand Institute for Plant & Food Research Limited, Private Bag 11600, Palmerston North 4442, New Zealand.
David A
DA
Brummell
Institute of Fundamental Sciences, Massey University, Private Bag 11222, Palmerston North, New Zealand Donald.Hunter@plantandfood.co.nz P.Dijkwel@massey.ac.nz.
Paul P
PP
Dijkwel
The New Zealand Institute for Plant & Food Research Limited, Private Bag 11600, Palmerston North 4442, New Zealand Donald.Hunter@plantandfood.co.nz P.Dijkwel@massey.ac.nz.
Donald A
DA
Hunter
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D002734:Chlorophyll / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D009154:Mutation; D010088:Oxidoreductases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D020641:Polymorphism, Single Nucleotide; D016415:Sequence Alignment
D029681:Arabidopsis Proteins; D008565:Membrane Proteins; D002734:Chlorophyll; C037184:chlorophyll b; C000604337:NON-YELLOW COLORING 1 protein, Arabidopsis; D010088:Oxidoreductases
Chlorophyll b reductase; Needle in the K-Stack; nonsense-mediated RNA decay; senescence; short chain dehydrogenase/reductase; stay-green.