Elevational patterns of functional diversity and trait of Delphinium (Ranunculaceae) in Hengduan Mountains, China.

Elevational patterns of trait occurrence and functional diversity provide an important perspective for understanding biodiversity. However, previous studies have mostly examined functional diversity at the community scale. Here, we examined large-scale patterns of trait occurrence and functional diversity in Delphinium along an elevational gradient from 1000 to 5700 m in the Hengduan Mountains, SW China. Elevational distribution and trait data of 102 Delphinium species were compiled to evaluate the patterns of interspecific traits, species richness, and functional diversity. We found that the distribution of species richness showed a unimodal curve that peaked between 3500 and 4000 m; functional diversity and traits showed different patterns along an elevational gradient. The functional diversity increased at a lower rate along an elevation gradient, whereas species richness continued to increase. Species with large ranges and non-endemic species were most affected by geometric constraints. Richness of species endemic to the Hengduan Mountains peaked at higher elevations, likely due to increased speciation and restricted dispersion under alpine conditions. We conclude that the middle elevation region is not only the functionally richest but also the most functionally stable region for Delphinium, which could be insurance against environmental change. Extreme conditions and strong environmental filters in an alpine environment may cause the convergence of species traits, which could relate to reducing nutrient trait investment and increasing reproductive trait investment. We conclude that large-scale studies are consistent with previous studies at the community scale. This may indicate that the relationship between functional diversity and species richness across different scales is the same.

Identification of pollen and pistil polygalacturonases in Nicotiana tabacum and their function in interspecific stigma compatibility.

KEY MESSAGE: The pollen and pistil polygalacturonases in Nicotiana tabacum were identified and found to regulate pollen tube growth and interspecific compatibility. Polygalacturonase (PG) is one of the enzymes catalyzing the hydrolysis of pectin. This process plays important roles in the pollen and pistil. In this research, the pollen and pistil PGs in Nicotiana tabacum (NtPGs) were identified, and their expression, localization and the potential function in the pollen and interspecific stigma incompatibility were explored. The results showed that 118 NtPGs were retrieved from the genome of N. tabacum. The phylogenetic tree and RT-qPCR analysis led to the identification of 10 pollen PGs; among them, two, seven and one showed specifically higher expression levels in the early development of anthers, during pollen maturation and in mature anthers, respectively, indicating their function difference. Immunofluorescence analysis showed that PGs were located in the cytoplasm of (1) mature pollen and (2) in vitro grown pollen tubes, as well as in the wall of in vivo grown pollen tubes. Four NtPGs in clade A were identified as the pistil PGs, and the pistil PGs were not found in clade E. Significantly higher PGs expression was recorded after incompatible pollination in comparison with the compatible stigma, indicating a potential function of PGs in regulating stigma incompatibility. The influence of PGs on pollen tube growth was explored in vitro and partly in vivo, showing that high PGs activity inhibited pollen tube growth. The application of PGs on the otherwise compatible stigma resulted in pollen tube growth inhibition or failure of germination. These results further supported that increased PGs expression in incompatible stigma might be partially responsible for the interspecific stigma incompatibility in Nicotiana.

Increased population epigenetic diversity of the clonal invasive species Alternanthera philoxeroides in response to salinity stress.

Epigenetic modification can change the pattern of gene expression without altering the underlying DNA sequence, which may be adaptive in clonal plant species. In this study, we used MSAP (methylation-sensitive amplification polymorphism) to examine epigenetic variation in Alternanthera philoxeroides, a clonal invasive species, in response to salinity stress. We found that salinity stress could significantly increase the level of epigenetic diversity within a population. This effect increased with increasing stress duration and was specific to particular genotypes. In addition, the epigenetic modification of young plants seems less sensitive to salinity than that of mature plants. This elevated epigenetic diversity in response to environmental stress may compensate for genetic impoverishment and contribute to evolutionary potential in clonal species.

Transient Stability of Epigenetic Population Differentiation in a Clonal Invader.

Epigenetic variation may play an important role in how plants cope with novel environments. While significant epigenetic differences among plants from contrasting habitats have often been observed in the field, the stability of these differences remains little understood. Here, we combined field monitoring with a multi-generation common garden approach to study the dynamics of DNA methylation variation in invasive Chinese populations of the clonal alligator weed (Alternanthera philoxeroides). Using AFLP and MSAP markers, we found little variation in DNA sequence but substantial epigenetic population differentiation. In the field, these differences remained stable across multiple years, whereas in a common environment they were maintained at first but then progressively eroded. However, some epigenetic differentiation remained even after 10 asexual generations. Our data indicate that epigenetic variation in alligator weed most likely results from a combination of environmental induction and spontaneous epimutation, and that much of it is neither rapidly reversible (phenotypic plasticity) nor long-term stable, but instead displays an intermediate level of stability. Such transient epigenetic stability could be a beneficial mechanism in novel and heterogeneous environments, particularly in a genetically impoverished invader.

Prioritizing fodder species based on traditional knowledge: a case study of mithun (Bos frontalis) in Dulongjiang area, Yunnan Province, Southwest China.

BACKGROUND: Livestock rearing is one of the oldest and most important types of smallholder farming worldwide. The sustainability of livestock production depends on the efficient utilization of locally available resources. Some traditional methods of raising livestock may offer valuable lessons in this regard. This study documented and evaluated local knowledge of wild forage plants in the Dulongjiang area in Southwest China in the context of rearing mithun (Bos frontalis) in order to provide a sound evidence base for tree fodder selection and the establishment of integrated tree-crop-livestock systems. METHODS: The snowball technique was used to identify key informants with specific knowledge about the topic. Free listing and semi-structured interviews were conducted with 58 households. Participatory investigation and transit walks were used to investigate potential fodder species. Ethnobotanical information was collected, documented and organized. RESULTS: Overall, 142 wild forage plants from 58 families and 117 genera were identified. Species of the Poaceae, Rosaceae and Urticaceae families were most abundant, with 16, 14 and 11 species respectively identified as fodder plants. Our results indicated that tree/shrub forage plays a major role in the diet of mithun, unlike that of other ruminants. Mithun prefers to browse and move around the forest in search of food, particularly rough and even barbed leaves. Tree species like Debregeasia orientalis, Saurauia polyneura and Rubus species were identified as being important fodder sources. Farmers in this area have traditionally relied on common property resources such as community-managed forests and grasslands to feed their livestock. Farmers have strong incentive to raise mithuns rather than other livestock species due to Dulong people's cultural preferences. CONCLUSIONS: The wide variety of plants cited by the informants demonstrate the importance of traditional knowledge in gathering information about forage resources. This diversity also offers the prospect of identifying promising species which could be used as fodder plants. Identifying such species and tree fodder species in particular could help smallholder farmers to integrate trees, livestock and crops as part of a sustainable farming system.

Selection of Native Tree Species for Subtropical Forest Restoration in Southwest China.

The use of native species in forest restoration has been increasingly recognized as an effective means of restoring ecosystem functions and biodiversity to degraded areas across the world. However, successful selection of species adapted to local conditions requires specific knowledge which is often lacking, especially in developing countries. In order to scale up forest restoration, experimental data on the responses of native species to propagation and restoration treatments across a range of local conditions are required. In this study, the restoration potential of 34 native tree species was evaluated based on nursery research and field planting experiments at a highly degraded site in a subtropical area of southwest China. We examined species performance in terms of germination rates as well as survival rates and growth over 2 years after planting. Of the 34 species examined, 25 had a germination percentage greater than 50%. Survivorship ranged from 0 to 97% across species and was greater than 50% for 20 species. Mean monthly growth increments varied between species. Pioneer species performed well, and 14 mid- and late-successional species performed reasonably well to very well in this study. However, the remaining 16 mid- and late-successional species performed poorly. These results indicate that carefully selected mid- and late-successional species can be effectively incorporated into mixed species plantings. This data can be used to inform restoration planning, helping to identify suitable species and so enhance the biodiversity and resilience of restored forests.

Development of EST-SSR markers for the invasive plant Tithonia diversifolia (Asteraceae).

PREMISE OF THE STUDY: Tithonia diversifolia (Asteraceae) is an invasive plant species that can outcompete natives and thus poses a great threat to biodiversity in introduced areas. Here, expressed sequence tag-simple sequence repeat (EST-SSR) markers were developed and characterized. METHODS AND RESULTS: Sixteen polymorphic microsatellite loci were isolated from T. diversifolia using transcriptome sequencing and bioinformatic screening. The number of alleles per locus varied from two to four alleles in 48 individuals from three populations. Most of these primers also amplified in T. rotundifolia and some even in Parthenium hysterophorus. CONCLUSIONS: These markers are useful for investigating the genetic structure and evolutionary process of T. diversifolia, which may provide important information for better management.

Development of microsatellite markers for the invasive weed Parthenium hysterophorus (Asteraceae).

PREMISE OF THE STUDY: Microsatellite primers were developed for Parthenium hysterophorus to investigate its genetic structure and genetic diversity. METHODS AND RESULTS: Using the combined biotin capture method, 15 microsatellite primer sets were isolated and characterized. All markers showed polymorphism, and the number of alleles per locus ranged from two to nine across 60 individuals from two populations. The observed and expected heterozygosities ranged from 0.117 to 0.750 and from 0.182 to 0.835, respectively. CONCLUSIONS: These markers will be useful for investigating the invasion history of this weed globally and to help characterize its invasiveness.

[Accuracy analysis of vegetation mapping for Meili Snow Mountain area, northwest Yunnan, China].

The Meili Snow Mountain (28 degrees 20'-28 degrees 33'N, 98 degrees 30'-8 degrees 52'E) is a very famous mountain in Northwest Yunnan of China by its rich and well protected biodiversity and Tibetan cultural diversity. By applying 3S (RS-Remote Sensing, GIS-Geography Information System, GPS-Global Position System) technology, the 1:50000 vegetation map of Meili Snow Mountain area (total about 332 km2) was drawn out. The vegetation in this area was classified into 18 vegetation types except for stone, glacier and river system. The vegetation map was rectified by applying the GPS points got from the fields. The numbers of GPS points were calculated by the formula of numbers of samples in statistics. 313 GPS points were used to rectify the vegetation map. The numbers were fit for the formula of numbers of samples in Statistics. The accuracy and verify of vegetation types distribution in the map was analyzed by building a Probability Error Matrix (PEM) and through the variance analysis. The results indicated that the overall accuracy (OA) of the vegetation map was 84.7%. The accuracy of vegetation map finished by 3S technology was lied on the area of the region and the grade of vegetation class first, but the grade of vegetation class classified by remote sensing technology disaccord with the traditional vegetation class system. The other factos deciding the accuracy of vegetation were the distinguish ability of Remote Sensing image, the accuracy of distinguish, and the numbers of the samples, including vegetation class experts knowledge.