Marker-assisted sex differentiation in date palm using simple sequence repeats

Abstract

Microsatellite markers containing simple sequence repeats (SSRs) are a valuable tool for genetic analysis. Our objective was to identify microsatellite markers that could be used to differentiate between male and female date palm (Phoenix dactylifera). The date palm is a dioecious plant whose sex cannot be determined until it reaches a reproductive age between 5 and 10 years. An early selection and/or differentiation of young seedlings into males and females could enhance breeding and assist research programs for genetic improvements of the date palm. Here, we report on the use of microsatellites for determining the sex of immature date palm. Using 14 microsatellite primer pairs with 129 date palm leaves and tissue culture samples from 34 cultivars which represent the major date palm diversity of Qatar, 254 microsatellite loci were detected, of these, 22 microsatellite loci could be used to identify 9 out of 12 male date palm samples (75%). The data also indicated that the heterozygous allele with the size 160/190 produced by the primer mPdCIR048 reoccurred 4 times exclusively in the 12 individual male samples but not in any of the 117 female date palm samples tested, and hence it is a promising candidate marker to detect male sex in date palm. Principal coordinate analysis (PCoA) of 12 male samples with 7 female Khasab cultivars produced 2 autonomous groups of males and females and similar results were observed with 13 female Shishi cultivars. Our results suggest that the SSR markers described here have potential in sex identification of date palm.

Sex-oriented research on dioecious crops of Indian subcontinent: an updated review

“…Additionally, Younis et al (2008) also reported five different male-specific amplification (of about 340, 1010, 375, 590 and 920 bp long) using five different ISSR primers. Another attempt was made to identify sex-specific microsatellite markers from date palm and 14 simple sequence repeat (SSR) primer pairs were used to screen 34 cultivars of date palm (Elmeer and Mattat 2012). Out of 254 numbers of detected microsatellite loci, 22 were found to identify 75% male samples of date palm.…”

Biodiversity, Genetic Diversity, and Genetic Resources of Date Palm

“…Several of these markers have been extensively used to study the genetic variation of date palm cultivars. These include randomly amplifi ed polymorphic DNA (RAPD), amplifi ed fragment length polymorphism (AFLP), and microsatellite markers (SSRs) (Ahmed et al 2013 ;Elmeer and Mattat 2012 ;Fig. 2.4 ).…”

“…Nevertheless, dioecy may have evolved several times in plants from bisexual (hermaphroditic or monoecious) ancestors by (1) a fi rst mutation causing male sterility generating a gynodioecious population and (2) a second mutation resulting in a decreased female fertility in the population leading to functional dioecy (Cherif et al 2012 ). Whether the evolution of dioecy results from selection for outcrossing or from sexual selection on separate components of male and female fi tness has been a subjected of considerable debate (Elmeer and Mattat 2012 ;Weiblen et al 2000 ). However, there is strong evidence suggesting that dioecy appears to have evolved most frequently via monoecy, perhaps through divergent adjustments of fl oral sex ratios between individual plants (Weiblen et al 2000 ).…”

Seedling date palms (Phoenix dactylifera L.) as genetic resources

“…It is more practicable to make a selection in the nursery of healthy females, along with a few healthy males, to establish a seedling-date plantation. Current molecular studies (Aberlenc-Bertossi, et al, 2010;Ageez and Madboly, 2011;Bekheet and Hanafy, 2011;Cherif et al, 2012;Elmeer and Mattat, 2012;Moghaieb et al, 2010;Younis et al, 2008) are expected to provide the means to identify the gender of seedlings at an early stage and thereby simplify propagation and breeding. Early selection of young seedlings could enhance date palm breeding programs and generate experimental male and female genetic stocks (Siljak-Yakovlev et al, 1996).…”

“…Early selection of young seedlings could enhance date palm breeding programs and generate experimental male and female genetic stocks (Siljak-Yakovlev et al, 1996). Molecular markers would facilitate the identification and selection of good male pollinators for use in breeding programs and could be used to select date palm with desired traits such as high yield and improved physical and chemical fruit characteristics (Elmeer and Mattat, 2012).…”