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Whether sex chromosomes are differentiated is an important aspect of our knowledge of dioecious plants, such as date palm (Phoenix dactylifera). In this crop plant, the female individuals produce dates, and are thus the more valuable sex. However, there is no way to identify the sex of date palm plants before reproductive age, and the sex-determining mechanism is still unclear. To identify sex-linked microsatellite markers, we surveyed a set of 52 male and 55 female genotypes representing the geographical diversity of the species. We found three genetically linked loci that are heterozygous only in males. Male-specific alleles allowed us to identify the gender in 100% of individuals. These results confirm the existence of an XY chromosomal system with a nonrecombining XY-like region in the date palm genome. The distribution of Y haplotypes in western and eastern haplogroups allowed us to trace two male ancestral paternal lineages that account for all known Y diversity in date palm. The very low diversity associated with Y haplotypes is consistent with clonal paternal transmission of a nonrecombining male-determining region. Our results establish the date palm as a biological model with one of the most ancient sex chromosomes in flowering plants.

Chlorogenic acid (5-CQA) is one of the major soluble phenolic compounds that is accumulated in coffee green beans. With other hydroxycinnamoyl quinic acids (HQAs), this compound is accumulated in particular in green beans of the cultivated species Coffea canephora. Recent work has indicated that the biosynthesis of 5-CQA can be catalyzed by a cytochrome P450 enzyme, CYP98A3 from Arabidopsis. Two full-length cDNA clones (CYP98A35 and CYP98A36) that encode putative p-coumaroylester 3'-hydroxylases (C3'H) were isolated from C. canephora cDNA libraries. Recombinant protein expression in yeast showed that both metabolized p-coumaroyl shikimate at similar rates, but that only one hydroxylates the chlorogenic acid precursor p-coumaroyl quinate. CYP98A35 appears to be the first C3'H capable of metabolising p-coumaroyl quinate and p-coumaroyl shikimate with the same efficiency. We studied the expression patterns of both genes on 4-month old C. canephora plants and found higher transcript levels in young and in highly vascularized organs for both genes. Gene expression and HQA content seemed to be correlated in these organs. Histolocalization and immunolocalization studies revealed similar tissue localization for caffeoyl quinic acids and p-coumaroylester 3'-hydroxylases. The results indicated that HQA biosynthesis and accumulation occurred mainly in the shoot tip and in the phloem of the vascular bundles. The lack of correlation between gene expression and HQA content observed in some organs is discussed in terms of transport and accumulation mechanisms.