Characterisation of post harvest shelf life in broccoli.Emma Skipper, Vicky Buchanan-Wollaston and David Pink.

Warwick HRI, University of Warwick, Wellesbourne, Warwick, CV35 9EF, UK.

Introduction:Broccoli (Brassica oleracea var italica) is a popular green vegetable consumed as a part of a healthy diet. Broccoli has a high vitamin and mineral content and contains health promoting properties such as antioxidants, flavonoids and glucosinolates. However broccoli has a notorious short shelf life displaying rapid senescence after harvest. Characteristics of a poor quality broccoli include a yellow appearance due to chlorophyll degradation, loss of flavour, reduced nutritional content and wilting as a result of a turgor loss, causing a high level of waste for retailers and consumers. The overall aim of this project is to investigate the effects of genetics on the gene expression and metabolite content of broccoli florets, to improve the shelf life of broccoli.

Previous studies using double haploid (DH) lines as a mapping population to measure yellowing using colour charts and chromameter

readings has located 9 QTLs relating to bud yellowing.

Project Aims:

•To improve the existing linkage map for the trait bud yellowing by incorporating more markers onto the linkage map.

•To identify one major QTL accounting for the majority of the variation in shelf life seen within the population for more detailed molecular analysis.

•To investigate the effects of the presence of the QTL on metabolite content. To link metabolite content with shelf life.

•To investigate gene expression patterns during senescence to identify genes controlled by the selected QTL.

Current work:

The DH population is being screened with 60 SSRs (short sequence of nucleotides, typically 2 to 5, that are repeated in tandem), know to be polymorphic between the parents of the cross, using PCR. The products of which are multiplexed using the sequencer facilities. The trace data from the sequencer is inputted into Genemarker software to look for polymorphisms between the parental lines for each marker. Peak height data and genotype data matrices are created from gene marker to be used in Joinmap to create a linkage map based on LOD ratios. Using phenotypic data and information from the linkage maps QTL analysis is performed to locate QTLs for the trait bud yellowing.

Future work:

•Analysis of key metabolites such as vitamin C, anthocyanins, glucoraphanin and glucobrassicin using high liquid performance chromatography (HPLC).

•Gene expression studies during senescence using microarrays. Potential to identify genes involved in senescence by comparison with the model plant system Arabidopsis

•Field trials in 2007 and 2008 to record phenotypic data to improve QTL definition for traits such as yellowing, head weight, diameter and circumference.

A linkage map of B. oleracea var italica based on the MAR34xGD33 DH population with

potential QTLs mapped relating to bud yellowing.

AC-CACG13

AA-CATG40

20

AA-CATM524AC-CAAM427

Na12_H0936

LG 2

BY3LCHR3, bCHR3

HCC3, CCHR3, HCC4, aCC4,

AC-CACM8AC-CTCM6

AC-CTAM50AC-CTAM102

AC-CACM912

AC-CTCM322AC-CAGM223AC-CATG225AC-CACM227

AA-CATM635

LG 1

BY1HCC4, aCHR3

HCHR3

BY2aCC4

AC-CTAM60

AC-CTAM18

AC-CATG612

Ol10_D0817

AC-CAGG435AC-CAGM436

BN83B146

AA-CTAM751AC-CTAG752AC-CTAG354

AC-CACG763

AA-CTAM290

LG 4

BY6LCC3, LCHR3

bCC3, bCHR3

HCC3, HCC4,CCC3, CCHR3

aCC4,

BY5aCC3

BY4aCC4

BY7CCC4

AC-CATM30

AC-CAGG314

AC-CAAG318

AC-CAAG421AC-CATM522

AC-CTAM12AA-CATG12

AA-CTAM823

AA-CATG1824Na12_C0829AC-CATG432

LG 5

Ol12_G040

AC-CACM68AC-CACM710

LG 7

AA-CTAG40

Na12_G128

AA-CATG839

AA-CTAG248

AA-CTAM550

AA-CTAM666

LG 8

AC-CTAM110

MB43

AC-CATG55

AC-CAGG28

LG6

BY8LCHR3,

bCC3, bCHR3

HCC3, HCC4, CCHR3, aCC4

AA-CATM70

AC-CTAG104

AC-CTCG212

AA-CTAG515

AC-CTCG118

AC-CTCM121

LG 9

BY9LCHR4

Days to yellowing of GD33, MAR34, the F1 and 59 DH lines as assessed using the R.H.S colour charts. The values are means of 6 heads per line per replicate per year.

Days to yellowing of the GD33 x MAR34 lines.

X

GD33 Mar34

Mar34 x GD33 F1 used to generate a doubled haploid mapping population

Distribution of yellowing of DH lines

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

4.50

5.00

MG364MG1810B

MG12627/9MG4127/9

GD33

MG13627/9

MG333MG185B

MG3927/9MG1825

MG350

MG8927/9MG1813

MG11827/9

MG330

F1

MG1810BMG12727/9

MG227/9MG1814

MG12427/9

MG10

MG927/9MG1822

MG12027/9

MG1824 MGUNID2

MG10027/9

MG110 MG334 MG116

MG1427/9MG1829

MG306 MG310MG188B

MG285MG57

MG1812MG48

MG1820MG308 MG327

MG187BMG13

MG183BMG346

MG9527/9

MG63 MG89MAR34

MGUNID1

MG18 MG99MG100

MG184BMG19

MG107BMG44

MG9827/9MG13227/9MG13827/9

DH Line

Days to Yellowing

GD33

Mar34

F1