Page 167 - Breeding and regulatory opportunities, Renaud

Broccoli phytochemical content

5.2.3 Broccoli Floret Samples and glucosinolate, tocopherol, and

carotenoid analysis

In order to analyse nutritional compounds of the broccoli heads, the following

procedure was followed: As plots approached maturity, ive broccoli head tissue

samples were harvested fresh from each subplot at each trial location and were

composited into a single sample per replication. The samples were frozen at -20oC

and shipped in a frozen state to the University of Illinois, Urbana-Champaign

where they were freeze-dried and assessed for nutritional phytochemicals. Each

sample was analyzed for the glucosinolates (glucoraphanin, glucobrassicin

and neoglucobrassicin), carotenoids (β-carotene, lutein, and zeaxanthin), and

tocopherols (δ-, γ-, α- tocopherol) by high-performance liquid chromatography

(HPLC) analysis using analytical protocols described in Brown et al. (2002) for

glucosinolates, and Ibrahim and Juvik (2009) for tocopherols and carotenoids.

Glucosinolates in lyophilized loret tissue samples were extracted and analysed

by HPLC using a reverse phase C18 column. Three hundred mg samples of

broccoli loret tissue were weighed out for extraction and the HPLC quantiica-

tion of the tocopherols and carotenoids.

5.2.4 Statistical Analysis

Various linear mixed models were used for the analysis of trait variation. We

followed the same methodology as described in Renaud et al. (2014), which was

comparable to the approach followed by Lorenzana and Bernardo (2008). For

itting the linear mixed models, GenStat 15 (VSNi, 2012) was used. The models

followed the set-up:

y = E + R(E) + G + G×E + e.

Here y is the phytochemical response. Term E represents the environment in a

very general sense, it includes all main efects and interactions of Season (S),

Location (L) and Management (M). For analyses per location, the terms involving

L were dropped. Similarly, for analyses regarding a speciic management

regime, the terms involving M were dropped. Term R(E) is the efect of replicate

within environment, and there were two or three replicates in individual trials.

G and G×E are genotype and genotype by environment interaction efects,

respectively. Finally e is a residual.

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