UNIVERSITE DE BOURGOGNE THÈSE Yongbo LIU - Université de ...

estimated. All the seeds of every harvested plant were germinated in greenhouse in conditions
as above. Seedlings were counted and sprayed with 2.5 g a.i. ha-1 chlorsulfuron in 300 L of
water (Glean, Du Pont de Nemours, France) at two to four leaves stage. Survived seedlings
were checked t wo weeks a fter s praying. S ince th e h erbicide-resistance i s en dowed b y a
dominant allele, every resistant seedling would be hybrid (Darmency et al. 1998)
Cage experiment
The experimental design consisted of 6 c ages, each containing 30 positions (18 positions for
the putative introgressed NM plants and the rest 12 positions for two populations chosen from
the three other regions). Positions were located at random and sown with 5 seeds per position.
The em erged s eedlings were co unted t o cal culate t he em ergence r ate, an d t hen r andomly
thinned t o one pl ant pe r pl ace. Houseflies, Musca d omestica, w ere c ontinuously pr ovided
inside th e c ages to f acilitate r andom p ollination.The da y w hen t he f irst flower ope ned w as
noted, and the number of days to flower was calculated. Wild radish was harvested when the
first siliques turned brown. The vegetative parts were separated from the pods and dried in an
oven f or 48h a t 80°C a nd w eighted. The s ilique w eight w as m easured, an d a rticles w ere
counted a nd w eighted. Per article weight (article w eight/ article num ber) a nd r eproduction
allocation (article weight/ plant weight) were estimated.
Statistic analysis
The Fisher test was employed for the percentage of petal color and flower pattern categories.
A Student-Newman-Keuls (SNK) test was used to compare the mean values of the flower and
silique characteristics among the four regions, and the fitness components of wild radish in
the field and the cages. All data, except of the petal color and flower pattern, were square-root
transformed to ensure a Normal distribution of residuals. A Discriminant Function Analysis
(DFA) w as a pplied t o t he s ix i ndependent m orphological c haracteristics of t he s iliques t o
identify the characteristics that best discriminate the four regions. A stepwise DFA was used
to e liminate v ariables w ith v ery little o r n o c ontributions to d iscriminant f unctions.
Discriminant f unctions w ere te sted f or th eir s ignificance u sing W ilk’s la mbda. T he
discriminant scores of the first two functions were used to carry out ANOVA and Contrast
test to check the difference among regions. In order to distinguish the differences among the
four r egions, a P rincipal C omponents A nalysis ( PCA) w as us ed f or t he va riables t hat w ere
measured directly on e ach individual: plant weight, number of siliques and seeds per plant,
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