The effect of temperature on stigmatic receptivity in sweet cherry (Prunus avium L.)

Plant reproduction is highly vulnerable to environmental conditions such as temperature and, consequently, planet warming may have significant consequences on the reproductive phase with serious implication in agricultural crops. Although pollen tube growth is clearly affected by temperature, little information is available on its effect on the female side and on flower receptivity. In this work, the effect of temperature has been evaluated on stigmatic receptivity of sweet cherry in vivo, in the laboratory, and in planta, in the field. Results herein show that temperature has a clear effect on the duration of stigmatic receptivity. Thus, whereas high temperature reduced stigmatic receptivity, low temperature enlarged it. The stigma lost the capacity to offer support first for pollen penetration, second for pollen germination and, finally, for pollen adhesion. The effect of temperature was more pronounced on pollen germination and penetration than on pollen adhesion. High temperature reduced the germination capacity of the pollen as early as the first day after anthesis, a time when no apparent signs of stigma degeneration are apparent. This clear effect of temperature on stigmatic receptivity and pollen performance may have clear implication in crop performance and in establishing screening criteria of best‐adapted genotypes.     

No reduction of female sexual receptivity following mating in a stalk‐eyed fly,Cyrtodiopsis dalmanni (Diptera: Diopsidae)

The level of female sexual receptivity is an important component of male and female reproductive success. In many insects, mating itself causes a sharp decline in female receptivity. This can be a direct result of the physical act of mating, or because of actions of sperm or seminal fluid proteins. The degree to which males can decrease female receptivity will directly affect their reproductive success, by altering the chance that their sperm will be used in fertilizations in the interval before the female mates again. In this study, we investigated the effect of mating on female receptivity in the sexually dimorphic stalk‐eyed fly, Cyrtodiopsis dalmanni. Our results showed no evidence for mating‐induced reductions in female receptivity. In addition, we found that matings with males that differed in eyespan did not cause differences in the level of female receptivity. There was also no evidence that females remated sooner when presented with large eyespan males. These results are surprising, given the indirect benefits that females gain from matings with large eyespan males. Finally we demonstrate that males do not appear to discriminate between females on the basis of female mating status.     

Differential pollination success in the course of individual flower development and flowering time in Gentiana pneumonanthe L. (Gentianaceae)

The effect of flowering time and anthesis stage on fecundity of Gentiana pneumonanthe L. (Gentianaceae) in a greenhouse experiment was studied. The species is self-compatible, not apomictic, and rarely self-pollinates spontaneously. On average, flowers lived for 11.4 days, starting with a male stage of 3.6 and continuing with a female stage of 7.9 days. Pollen viability was highest during the first two days of the male stage, but never exceeded 50%. Seed-set from cross-pollination was higher earlier in the flowering period (77%) than later (63Vo). For self-pollinations, no significant difference was observed. The success of hand-pollinations declined dramatically after the fourth day of the female stage. Self-pollination yielded lower seed-set on the first day of the female stage than on the following three days. Also, there was a significant difference in seed-set between self- and cross-pollinations (25% vs 55%, respectively) only on the first day. This suggests that selection against self pollen was stronger during the first stage of the female phase and weakened as the stylar tissue aged. In conclusion, two different ways to enhance outcrossing were observed: (1) within the population's flowering period, and (2) within an individual flower's lifespan. Both may have important effects on the genetic variability of G. pneumonanthe offspring under unfavourable conditions. Wese include small population size (associated with reduced pollinator service), general pollinator scarcity, or rainy summers.     

The pollination ecology of Grevillea beadleana McGillivray,an endangered shrub from northern New South Wales,Australia

Grevillea beadleana (Proteaceae) is an endangered species known from five populations in northern New South Wales, Australia. The reproductive ecology of G. beadleana was compared in two populations with a ten-fold difference in the number of plants. Grevillea beadleana was found to be self-compatible in both populations and an examination of pollen viability and stigma maturation revealed that the species is protandrous. Flowering within inflorescences is acropetallous. In the first season plants in the largest population produced approx. ten-fold more inflorescences than those in the smaller population and, although the number of flowers per inflorescence did not vary significantly between populations the first season, the larger population produced more fruit per inflorescence than the smaller population. However, fruit to flower ratios were less than 0.2 in both seasons and populations. In both populations the number of fruit was significantly greater at the proximal end of the inflorescence, where flowers open first, compared with medial and distal positions. Several bird species were observed visiting flowers, although few birds were recorded foraging at plants in the smaller population. Within both populations, birds tended to make more within- than between-plant visits. Self-compatibility, acropetally and proximal fruit-set, combined with the predominantly within-plant movement of honeyeaters, suggests inbreeding may be common within both populations of G. beadleana. Pollination and fruiting success are discussed for G. beadleana and breeding systems among rare and common taxa in Grevillea are reviewed.     

Sexual antagonism in the pistil varies among populations of a hermaphroditic mixed‐mating plant

Sexual conflicts and their evolutionary outcomes may be influenced by population‐specific features such as mating system and ecological context; however, very few studies have investigated the link between sexual conflict and mating system. The self‐compatible, mixed‐mating hermaphrodite Collinsia heterophylla (Plantaginaceae) is thought to exhibit a sexual conflict over timing of stigma receptivity. This conflict involves (i) delayed stigma receptivity, which intensifies pollen competition, and (ii) early fertilization forced by pollen, which reduces seed set. We investigated the potential for the conflict to occur under field conditions and performed glasshouse crosses within eight populations to assess its consistency across populations. Flowers were visited, and produced seeds after pollination, at all developmental stages, suggesting that the conflict can be of significance under natural conditions. In the glasshouse, early pollination imposed costs in all populations. Overall, the timing of first seed set was most strongly affected by the maternal parent, denoting stronger female than male ability to influence the onset of stigma receptivity. Crosses also revealed a negative relationship between donor‐ and recipient‐related onset of receptivity within individuals, a novel result hinting at trade‐offs in sex allocation or a history of antagonistic selection. Neither timing of stigma receptivity, timing of first seed set, nor pollen competitive ability covaried with population outcrossing rate. In conclusion, these results indicate that sexually antagonistic selection may be present in varying degrees in different populations of C. heterophylla, but this variation does not appear to be directly related to mating system variation.     

Pollination biology of Paeonia jishanensis T. Hong & W.Z. Zhao (Paeoniaceae), with special emphasis on pollen and stigma biology

The endangered wild tree peony. Paeania jishanensis T. Hong & W. Z. Zhao (formerly P. suffruticosa Andr. ssp. spontanea (Rehd.) S.G. Haw & L. A. Lauener) is one of the most important ancestral stocks of cultivated tree peony, P. suffruticosa Andr. Study of the natural population atjishan, Shanxi Province revealed that the seed set was very low (2.1 seeds per carpel). The low seed set should not be attributed to viable pollen limitation because the plant produces a great quantity of pollen and 36–75% of pollen is TTC-tested viable. Stigmas became receptive almost one day after the flower opened, and receptivity lasted for several days. All the stigmas were sufficiently pollinated, and pollen germinated readily on the wet crest of stigmas irrespective of whether cross pollen or self pollen was used. Hand-pollination showed that this plant was self-incompatible. No seed was harvested after self-pollination, while cross-pollination yielded 2.4 seeds per carpel. Many pollen tubes were recorded in the stigma but extremely few in the ovary chamber. This phenomenon indicated diat the self-incompatible system was activated when pollen tubes reached the ovary wall.     

四倍体和二倍体盾叶薯蓣的花粉活力及柱头可受性分析

盾叶薯蓣（Dioscorea zingiberens C．H．Wright）叶片呈盾形,叶面有不规则的黄白色斑块;蒴果干燥后呈蓝黑色,表面常附有白色粉状物;染色体数20;花粉两端略尖,外壁具有明显条纹。盾叶薯蓣根茎横生,俗称黄姜,可用于治疗皮肤感染、软组织损伤、蜂蜇虫咬及各种外科炎症。盾叶薯蓣根茎所含的薯蓣皂苷元（皂素,diosgenin）是合成甾体激素药物的主要原料,除具有抗炎、避孕等作用外,还可月季于合成镇痛药、杀虫剂及治疗冠心病的药物。     

Waiting for wasps: consequences for the pollination dynamics of Ficus pertusa L.

Abstract. Pollination of fig trees depends on mutualist wasps that reproduce within their flowers. Until recently, it was assumed that there was a short window of time during which a fig crop could be pollinated. Hence, pollination of figs was thought to depend on extreme efficiency of the wasps in locating receptive trees. In that context, extensive data on the Costa Rican fig tree Ficus pertusa L. have been very difficult to understand. In F. pertusa , figs of different crops attract wasps at different stages of their development. The crops that attract wasps the earliest in their development are the most heavily visited ones, but mature the fewest pollinator offspring and seeds on a per-fig basis. Using simulation models of pollinator population dynamics and field data, we show that (i) attractiveness of a crop is prolonged, (ii) wasps prefer large figs when given a choice, and (iii) the observed pattern of preferential early visitation of crops can be explained by temporal variations in pollinator abundance. This emphasizes the importance of population-level mechanisms to explain the fig/fig wasp mutualism.