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Cotinus is an oligo‐specific ornamentally valuable genus with a disjunct distribution in the Northern Hemisphere. Traditionally, the taxonomy of Cotinus was mainly based on leaf morphological characteristics. However, the limited availability of genomic information greatly hindered the study of molecular evolution and phylogeny of this genus. This study sequenced the chloroplast (cp) genomes of all currently recognized taxa of Cotinus, including three species and four varieties. A comparative analysis was performed to investigate their cp genome characteristics and evolution. Furthermore, we inferred the phylogenetic relationships of Cotinus based on whole cp genomes, protein‐coding genes, and nuclear ITS data. All cp genomes exhibited a typical quadripartite structure with genome sizes ranging from 158,865 to 160,155 bp. A total of 113–114 genes were identified in the genomes. Seven non‐coding and four coding regions were identified as the most divergent hotspots for potential molecular barcodes and phylogenetic markers. Selection pressure analysis showed that there had been positive selection on genes matK and rps8 in the Cotinus cp genomes. Phylogenetic results confirmed that Cotinus is a monophyletic group but the widely distributed species Cotinus coggygria is not monophyletic. The divergence‐time analysis suggested that Cotinus underwent an evolutionary divergence from the middle Eocene and rapid adaptive radiation from the middle Miocene. This study revealed new insights into the cp genome evolution and phylogeny of Cotinus and related taxa. [ABSTRACT FROM AUTHOR]

Sexual dimorphism in dioecious plants often occurs as a consequence of the different resource requirements of females and males, especially during reproduction. The contrasting reproductive roles of the sexes can influence the phenology of growth, plant size, and flowering time, with implications for the intensity of competitive interactions within and between the sexes. Here, we investigate the influence of contrasting nutrient regimes and intra‐sexual and inter‐sexual competition on the expression of sexual dimorphism in life‐history traits and biomass allocation throughout the life cycle of the dioecious annual Rumex hastatulus Baldw. (Polygonaceae). Development of a sex‐specific marker enabled us to quantify the influence of competition on sex‐specific differences in mortality and vegetative traits. We were particularly interested in determining whether the overall performance of the sexes might differ between the two forms of intra‐specific competition, potentially providing evidence for sexual specialization in resource acquisition and niche differentiation. Our results indicated that although patterns of sexual dimorphism were dynamic, they were largely insensitive to nutrient conditions. We found that intra‐sexual competition was more severe than inter‐sexual competition, differentially affecting mortality and most traits during the vegetative and particularly the reproductive stage of the life history. Female trait values generally increased more under inter‐sexual than intra‐sexual competition in comparison to males. Our findings are consistent with temporal niche differentiation resulting from sexual specialization for different resource requirements and provide evidence for the "Jack Sprat effect." [ABSTRACT FROM AUTHOR]

Date palm (Phoenix dactylifera L.) is cultivated in arid and semiarid regions worldwide. Given the dioecious nature of this plant, gender identification is very important at the seedling stage. Molecular markers are very effective tools that help in gender identification at this stage. A sequence characterized amplified region (SCAR) marker linked to sex-specific regions in the genome of date palm was developed. Of the 300 tested randomly amplified polymorphic DNA (RAPD) primers, only one primer (OPC-06) produced reproducible band (294 bp) in male plants. The PCR product of this primer was cloned and sequenced. The specific primers were synthesized for amplification of a 186 bp fragment in male date palm plants. These primers were validated in male and female date palm plants, wherein the designed SCAR marker was reported only in male plants and no amplification was observed in female plants. The developed SCAR marker was used with seedlings of date palm and proved very effective in identification of gender. [ABSTRACT FROM AUTHOR]

PREMISE OF THE STUDY:: In dioecious species, determining the sex of individual plants from one‐time phenological observations is rarely feasible when some individuals capable of reproducing are not flowering or fruiting at the time of observation. Currently, sexing those individuals requires long‐term phenological data on individuals and populations, but such data are rarely available or feasible to collect. We tested the hypothesis that differences in soil pollen concentrations beneath the crowns of female and male plants would exist and be sufficient to reliably determine the sex of the individual plant overhead in a dioecious species. We predicted that soil pollen concentrations beneath male plants would be significantly higher than beneath female plants because only males produce pollen and pollen should accumulate in the soil underneath the male plants over repeated flowering events. METHODS:: We collected samples from surface soil under both sexes of the insect‐pollinated dioecious shrub, Aucuba japonica (Garryaceae). KEY RESULTS:: Pollen grains were present in surface soil in both Oe and A horizons, and mean pollen concentration under males was significantly higher than under females. Pollen concentrations beneath males were positively correlated with male plant height, potentially reflecting greater pollen production by larger individuals. CONCLUSIONS:: Considering the small plant size and relatively low pollen production of A. japonica, this method may hold promise for sexing other dioecious species in the absence of direct phenological data. Our phenology‐free and relatively low‐cost method for sexing dioecious plants may be especially useful in tropical forests where many species are dioecious. [ABSTRACT FROM AUTHOR]