-->Plant Ecology and Biodiversity

Effects of pollination mode and fruit type on reproductive phenology of woody plants

2017/4/7 11:47:51

We examined the effects of pollination mode and fruit type on the reproductive phenology of woody plant species at the Botanical Garden of the Institute of Botany, Chinese Academy of Sciences, Beijing, China(39°54'N, 116°12'E). Phylogenetically Independent Contrasts(PIC)and Wilcoxon Rank Sum test were applied to analyze 170 individuals from 84 species, and the result of Wilcoxon Rank Sum test was a reference for PIC test. Our results showed that pollination mode significantly influenced the reproductive phenology of woody plants. Wind-pollinated trees flowered and fruited earlier than insect-pollinated trees. Fleshy-fruit species fruited earlier than nonfleshy-fruit species, but this relationship disappeared when phylogeny was taken into consideration. Fruit type had no effect on flowering phenology. The intervals between flowering and fruiting were not significantly different in both pollination mode group and fruit type group. These results suggest that plant intrinsic attributes, such as pollination mode and fruit type, have significant influence on the reproductive phenology of woody plants. These attributes are closely related to special phenological phase or reproductive organ may affect this phenological phase more.

Intra- and inter-specific variations of the leaf unfolding phenology in a subtropical broad-leaved forest

2017/4/7 11:47:51

Leaf unfolding phenology in plants can be determined by genetic factors, biotic and abiotic environmental factors. However, limited information was available about the leaf unfolding phenology of evergreen broad-leaved forest, and its phylogenetic conservatism has not been investigated. In order to better understand the maintaining mechanism of species coexistence in lower subtropical evergreen broad-leaved forest and to predict species responses to global changes, we used the phenological data of 44 species containing 112 individuals of trees, which obtained from Dinghushan(DHS)Arboretum, Chinese Academy of Sciences(CAS), to explore the effects of climate, phylogenetic and the intra- and inter-specific variations on leaf unfolding date. The results showed that leaf unfolding date in DHS National Nature Reserve peaked in the period from March to June, and had been little influenced by climate factors. There were distinct intraspecific variation between different species, and Craibiodendron scleranthum var. kwangtungense showed the greatest coefficient of variation(CV, 0.74), while Machilus kwangtungensis had the smallest coefficient of variation(CV, 0.09). According to the phylomatic tree based on APG Ⅲ, no significant effect of phylogeny on the leaf unfolding date was detected, indicating that close related species did not have the tendency to leaf-out at similar time. This study suggests that exploring the intra- and inter-specific variations of leaf unfolding phenology is important for understanding the ecosystem processes, such as the carbon cycle, the material and energy flow, and the adaptation of different tree species to climate changes.

Genetic relationship analysis of Gerbera delavayi from nine populations based on ITS sequences

2017/4/7 11:47:51

Ribosomal DNA(rDNA)ITS of nine populations of Gerbera delavayi in Southwest China were amplified, sequenced and compared with G. jamesonii. The relationships of geographic distance and genetic distance of nine populations were studied. The NJ phylogenetic tree was also constructed. The results were as follows:(1)The whole length of ITS sequences of G. delavayi was 600-700 bp, the average length was 657 bp, the length of ITS1 was 243-246 bp,(G+C)amounted for 45.67%-46.80%, the length of 5.8S was 191-193 bp,(G+C)amounted for 58.60%-58.61%, the length of ITS2 was 220-221 bp,(G+C)amounted for 57.00%-57.45%. A total of 22 variable sites(ITS1, 7; 5.8S, 2 and ITS2, 3)were found.(2)The genetic distance had positive correlation with the geographic distance of G. delavayi(r2=0.652). The genetic differentiation distance was 0.001 1-0.024 3, among which the genetic distance between Pu'er and other population was the largest.(3)Nine populations were divided into three branches, in which Pu'er populations was separated as the first group. The second group contained Lijiang and Eryuan provenances. The other six populations(Fuyuan, Wuding, Dechang, Shilin, Xinping and Kaiyuan)were clustered together. RDNA ITS sequence analysis could be applied to study the population genetic of G. delavayi. The results provides reference for the protective development of G. delavayi.

Variation in floral sex allocation within inflorescences of Alpinia blepharocalyx

2017/4/7 11:47:51

Intra-inflorescence variation in floral sex allocation is commom in hermaphroditic plants, and several non-exclusive hypotheses, including resource competition, architectural effect, the mating environment or non-uniform pollination, have been formulated to explain this phenomenon. To test the above hypotheses, we investigated floral sex allocation within racemes of two morphs in heterodichogamous Alpinia blepharocalyx. Flowers on each raceme were sampled and assigned to one of three relative positions: basal, middle and distal, variations in pollen number, ovule number, the pollen/ovule(P/O)ratio, and fruit and seed production among positions within racemes were quantified. Ecological causes for fruit and seed production were evaluated by flower removal and supplemental pollination, directional movements of pollinators within racemes were also observed. Pollen number per flower did not change with relative positions, ovule number per flower declined from basal to distal postions, and the P/O ratio per flower increased from basal to distal positions in both morphs, thus distal flowers performed male-biased function. Under natural pollination condition, fruit and seed set declined distally in both morphs, therefore, female reproductive success at the relative postions showed the same pattern as that of sex allocation at flowering stage. After hand-supplemental pollination, both fruit and seed set decreased from basal to distal positions in each morph, thus, lower female reproductive success at distal postions could not be attributed to pollen limitation. After the removal of basal and middle flowers, the fruit and seed set of distal flowers did not differ from those of basal flowers when extra pollen was added, indicating that the low fruit and seed set of distal flowers was simply attributed to resource competition rather than architectural effect. Pollen number and the P/O ratio was hi-gher for protogynous than protandrous morph, but fruit and seed set did not differ between morphs, indicating that sexual specialization occurred at flowering stage. Pollinators tended to visit basal flowers first and then moved upwards within an inflorescence, which would result in directional pollen flow from basal to distal flowers. Both inter-flower resource competition and directional pollinator movement may be responsible for intra-inflorescence variation in floral sex allocation of A. blepharocalyx.

Development and screening of SSR markers in Rhodiola alsia with magnetic beads method

2017/4/7 11:47:51

FIASCO magnetic beads method was utilized to develop polymophic SSR markers of Rhodiola alsia, a precious species endemic to the Qinghai-Xizang Plateau. Two SSR marker probes,(AG)15 and(AC)15, were used to construct enriched SSR library and 2 500 positive clones were obtained. Then 1 200 positive clones were randomly selected to check and within which 400 clones were found with polymorphism. Half of the polymorphic clones were randomly chosen for sequencing and 105 SSR loci were achieved. Subsequently, 105 pairs ofprimers were designed by online software, primer 3-2.3.4, for amplifying the SSR sequences. Among which, a total of 45 pairs of primers were positive for amplification and the sequences amplified by thirteen pairs showed high genetic polymorphism when detected in four far apart natural populations with 24 individuals. Afterwards, the whole of 80 individuals in the four populations were employed to check the thirteen SSR loci. The average number of alleles per locus(A)was around 9.192, the mean of observed heterozygosity(Ho)and the expected heterozygosity(He)were around 0.712 and around 0.734, respectively. Such an extraordinary polymorphism was enough to meet the needs of future research. However, several loci were significantly deviated from Weinberg-Hardy equilibrium(P<0.01)in some populations, which may be due to the fact that the population of the actual study could not reach the ideal state of Weinberg-Hardy's law. Combining SSR polymorphic loci developed previously based on EST(Expressed Sequence Tag)sequences, this study provides a set of serviceable tools for population genetic structure analysis on R. alsia and other researches based on SSR markers.

Analysis of phenotypic character genetic diversity of 40 lines of Picria felterrae

2017/4/7 11:47:51

Plant genetic diversity has been one of the hot spots in the research into germplasm resources. To disclose the genetic diversity of cultivated germplasm of Picria felterrae, we selected 40 lines from perennially cultivated individuals based on morphological differences and analyzed species variation and genetic diversity with yield, active ingredient content as well as morphological characters including the stem, leaf and flower as the indicator; and wemade cluster analysis to obtain the genetic relationships between lines. The results showed that there was much genetic variance in the content of picfeltarraenins I_A and I_B, the coefficients being 24.225% and 17.853%, respectively; and the genetic diversity indexes were high, 1.920 and 2.075, respectively. For the yield, the coefficient of genetic variance was comparatively low, only 3.637%, and the genetic diversity index was 1.884. There was also much genetic variance in other phenotypic characters, among which the coefficient of genetic variance of flower color was 127.794%. All genetic diversity indexes for numerical characters were higher than one while those for descriptive characters were lower than one. The test materials were divided into four groups in the cluster analysis: Group Ⅰ consisted of seven lines which had a high yield and related indexes on average; Group Ⅱ included eight lines which had the longest stem nodes and whose other indexes were at or below the moderate level; Group Ⅲ comprised 20 lines with low indexes in all respects; and Group IV included five lines, all of which were high in yield and content of picfeltarraenins and had a better integrated index. The correlation analysis showed that the content of picfeltarraenin I_A was significantly related to leaf margin characters, and the yield was significantly correlated to stem node length and primary and final branching numbers, so the above four characters should be given priority when selecting the best germplasm. The results indicate that extensive variation and high genetic diversity are present in current cultivated individuals of Picria felterrae, which can be used as a reference for the utilization of resources of that species.

Preliminary investigation on biodiversity of wild lianas in Jiangsu

2017/4/7 11:47:51

There are 153 species of wild lianas, belonging to 74 genera and 35 families based on several field investigations and literature consulted on wild lianas. There is one species of fern belonging to one genus and one family,twenle species of monocotyledons belonging to four genera and three families and 140 species of dicotyledonous belonging to 69 genera and 31 families; wild lianas in Jiangsu are made primarily of depauperate family(genera)and single species family(genera). The geographical elements of wild lianas are complex, and the floristic element analysis reveals that wild lianas with tropical features is dominant and influenced by temperate components. The woody lianas occupy a certain proption(56.58%), where woody lianas belong to seventeen families, such as Lardizabalaceae and Menispermaceae, while the proption taken up by herb lianas are slightly lower, where herb lianas belong to thirteen families, such as Stemonaceae and Asclepiadaceae, and the rest of families are consisting of woody and herb, such as Liliaceae and Vitaceae. The climbing patterns of wild lianas in can be divided into four types, among which the twining account for 40.13%, and the following are curing(30.26%), hooking(22.37%)and adhering(7.24%). In the lianas sexual system, the hermaphrodites account for 76.97%, the dioecious for 19.74% and themonoecious for 3.29%. The inflorescence components are abundant, and the indefinite inflorescence is in absolutely dominant(71.05%).