Plant apomixis is rare in Himalayan high-alpine flora

Gametophytic apomixis is a way of asexual plant reproduction by seeds. It should be advantageous under stressful high altitude or latitude environment where short growing seasons, low temperatures, low pollinator activity or unstable weather may hamper sexual reproduction. However, this hypothesis remains largely untested. Here, we assess the reproductive mode in 257 species belonging to 45 families from the world's broadest alpine belt (2800-6150 m) in NW Himalayas using flow cytometric seed screen. We found only 12 apomictic species, including several members of Poaceae (Festuca, Poa and Stipa), Rosaceae (Potentilla) and Ranunculaceae (Halerpestes, Ranunculus), which are families typical for high apomict frequency. However, several apomictic species were newly discovered, including the first known apomictic species from the family Biebersteiniaceae (Biebersteinia odora), and first apomicts from the genera Stipa (Stipa splendens) and Halerpestes (Halerpestes lancifolia). Apomicts showed no preference for higher elevations, even in these extreme Himalayan alpine habitats. Additional trait-based analyses revealed that apomicts differed from sexuals in comprising more rhizomatous graminoids and forbs, higher soil moisture demands, sharing the syndrome of dominant species with broad geographical and elevation ranges typical for the late-successional habitats. Apomicts differ from non-apomicts in greater ability of clonal propagation and preference for wetter, more productive habitats.

Effects of arbuscular mycorrhizal fungi and maternal plant sex on seed germination and early plant establishment

•

PREMISE OF THE STUDY

Arbuscular mycorrhizal fungi usually enhance overall plant performance, yet their effects on seed germination and early plant establishment, crucial steps in plant cycles, are generally overlooked. In gynodioecious species, sexual dimorphism in these traits has been reported, with females producing seeds that germinate at a faster rate than seeds from hermaphrodites.•

METHODS

Using the gynodioecious plant Geranium sylvaticum, I investigated in a greenhouse experiment whether the presence of arbuscular mycorrhizal spores affects seed germination and early plant establishment, examining at the same time whether the sex of the mother producing the seeds also influences these parameters and whether sex-specific interactions between these two factors exist.•

KEY RESULTS

The presence of arbuscular mycorrhizal spores in the soil decreased seed germination, did not affect plant survival, but did increase plant growth. Moreover, no significant differences in seed traits were detected between the sexes of the plants producing the seeds.•

CONCLUSIONS

This study demonstrates that arbuscular mycorrhizal fungi may have contrasting effects for plants during early life stages and that mycorrhizal effects can take place even at the precolonization stage.

Old-growth Platycladus orientalis as a resource for reproductive capacity and genetic diversity

AIMS

Platycladus orientalis (Cupressaceae) is an old-growth tree species which distributed in the imperial parks and ancient temples in Beijing, China. We aim to (1) examine the genetic diversity and reproductive traits of old-growth and young populations of P. orientalis to ascertain whether the older populations contain a higher genetic diversity, more private alleles and a higher reproductive output compared with younger populations; (2) determine the relationships between the age of the population and the genetic diversity and reproductive traits; and (3) determine whether the imperial parks and ancient temples played an important role in maintaining the reproductive capacity and genetic diversity of Platycladus orientalis.

METHODS

Samples from seven young (younger than 100 yrs.) and nine old-growth (older than 300 yrs.) artificial populations were collected. For comparison, three young and two old-growth natural populations were also sampled. Nine microsatellite loci were used to analyze genetic diversity parameters. These parameters were calculated using FSTAT version 2.9.3 and GenAlex v 6.41.

IMPORTANT FINDINGS

The old-growth artificial populations of P. orientalis have significantly higher genetic diversity than younger artificial populations and similar levels to those in extant natural populations. The imperial parks and ancient temples, which have protected these old-growth trees for centuries, have played an important role in maintaining the genetic diversity and reproductive capacity of this tree species.

О РАСПРОСТРАНЕНИИ ГИНОДИЭЦИИ У ЦВЕТКОВЫХ РАСТЕНИЙ, "БОТАНИЧЕСКИЙ ЖУРНАЛ"

На основании литературных данных и собственных наблюдений составлен новый список гинодиэцичных растений, включающий в себя 1126 видов из 89 семейств покрытосеменных мировой флоры. Анализируются особенности распространения гинодиэции (женской двудомности) среди цветковых растений. В настоящее время у двудольных растений гинодиэция обнаружена у представителей 77 семейств, 278 родов и 1044 видов, а у однодольных — у 12 семейств, 25 родов и 82 видов. Гинодиэция ассоциируется главным образом с многолетними травами, умеренным климатом, энтомофильным опылением.

Parthenogenesis maintains male sterility in a gynodioecious orchid

The invasion of male-sterile (female) individuals into hermaphroditic populations, leading to gynodioecy, is common in flowering plants. Both theoretical and empirical studies have shown that as the frequency of females increases in a population, pollen limitation reduces seed production more in females than in hermaphrodites, leading to higher fitness for hermaphrodites and a consequent decrease in female frequency. Here we show that contrary to this expectation, females of the gynodioecious orchid Satyrium ciliatum are maintained only in populations that experience high pollen limitation caused by low pollinator service and high pollen herbivory. This species avoids the typical problem of pollen limitation for seed production and can therefore maintain high frequencies of females in pollen-limited populations because females produce more seeds than hermaphrodites via facultative parthenogenesis in the absence of pollinia. Our results therefore demonstrate that parthenogenesis is a novel mechanism favoring the maintenance of gynodioecy.