Functional identification of specialized diterpene synthases from Chamaecyparis obtusa and C. obtusa var. formosana to illustrate the putative evolution of diterpene synthases in Cupressaceae

Chamaecyparis obtusa and C. obtusa var. formosana of the Cupressaceae family are well known for their fragrance and excellent physical properties. To investigate the biosynthesis of unique diterpenoid compounds, diterpene synthase genes for specialized metabolite synthesis were cloned from C. obtusa and C. obtusa var. formosana. Using an Escherichia coli co-expression system, eight diterpene synthases (diTPSs) were characterized. CoCPS and CovfCPS are class II monofunctional (+)-copalyl diphosphate synthases [(+)-CPSs]. Class I monofunctional CoLS and CovfLS convert (+)-copalyl diphosphate [(+)-CPP] to levopimaradiene, CoBRS, CovfBRS1, and CovfBRS3 convert (+)-CPP to (-)-beyerene, and CovfSDS converts (+)-CPP to (-)-sandaracopimaradiene. These enzymes are all monofunctional diterpene syntheses in Cupressaceae family of gymnosperm, and differ from those in Pinaceae. The discovery of the enzyme responsible for the biosynthesis of tetracyclic diterpene (-)-beyerene was characterized for the first time. Diterpene synthases with different catalytic functions exist in closely related species within the Cupressaceae family, indicating that this group of monofunctional diterpene synthases is particularly prone to the evolution of new functions and development of species-specific specialized diterpenoid constituents.

Cloning and functional characterization of three sesquiterpene synthase genes from Chamaecyparis formosensis Matsumura

Terpene synthase (TPS) analysis may contribute to a better understanding of terpenoids biosynthesis and the evolution of phylogenetic taxonomy. Chamaecyparis formosensis Matsumura is an endemic and valuable conifer of Taiwan. Its excellent wood quality, fragrance, and durability make it become the five precious conifers in Taiwan. In this study, three sesquiterpene synthase genes that belong to the TPS-d2 clade were isolated and characterized through in vitro reaction of recombinant protein and in vivo reaction of Escherichia coli heterologous expression system. The main product of Cf-GerA was germacrene A using GC/MS analysis, while the product of Cf-Aco and Cf-Gor were identified as acora-4(14),8-diene and (5R,6R,10S)-α-gorgonene by using NMR analysis. These are the first reported enzymes that biosynthesize acora-4(14),8-diene and (5 R,6 R,10 S)-α-gorgonene. Both sesquiterpene synthases may isomerize the farnesyl pyrophosphate substrate to nerolidyl pyrophosphate for further cyclization. Cf-Aco may catalyze 1,6-cyclization of nerolidyl cation while Cf-Gor may catalyze through an uncharged intermediate, isogermacrene A.

Drought affects the fate of non-structural carbohydrates in hinoki cypress

Tree species that close stomata early in response to drought are likely to suffer from an imbalance between limited carbohydrate supply due to reduced photosynthesis and metabolic demand. Our objective was to clarify the dynamic responses of non-structural carbohydrates to drought in a water-saving species, the hinoki cypress (Chamaecyparis obtusa Sieb. et Zucc.). To this end, we pulse-labeled young trees with 13CO2 10 days after the beginning of the drought treatment. Trees were harvested 7 days later, early during drought progression, and 86 days later when they had suffered from a long and severe drought. The labeled carbon (C) was traced in phloem extract, in the organic matter and starch of all the organs, and in the soluble sugars (sucrose, glucose and fructose) of the most metabolically active organs (foliage, green branches and fine roots). No drought-related changes in labeled C partitioning between belowground and aboveground organs were observed. The C allocation between non-structural carbohydrates was altered early during drought progression: starch concentration was lower by half in the photosynthetic organs, while the concentration of almost all soluble sugars tended to increase. The preferential allocation of labeled C to glucose and fructose reflected an increased demand for soluble sugars for osmotic adjustment. After 3 months of a lethal drought, the concentrations of soluble sugars and starch were admittedly lower in drought-stressed trees than in the controls, but the pool of non-structural carbohydrates was far from completely depleted. However, the allocation to storage had been impaired by drought; photosynthesis and the sugar translocation rate had also been reduced by drought. Failure to maintain cell turgor through osmoregulation and to refill embolized xylem due to the depletion in soluble sugars in the roots could have resulted in tree mortality in hinoki cypress, though the total pool of carbohydrate was not completely depleted.

Discovery and characterization of diterpene synthases in Chamaecyparis formosensis Matsum. which participated in an unprecedented diterpenoid biosynthesis route in conifer

Chamaecyparis formosensis Matsum. is an endemic and precious coniferous species of Taiwan, and is known for a high abundance of specialized metabolites, which contributes to the excellent timber durability. Several terpenoids were identified and isolated from C. formosensis wood and needles, and exhibit anti-fungal and anti-bacterial bioactivities, which may participate in plant defense against pathogens. In various identified compounds, not only cadinene and ferruginol, were identified in C. formosensis extracts but also unique diterpenoids, which include pisferal, totarol, and derivates of isoabienol. To understand the biosynthesis of these specific diterpenoids, we conducted a series of functional characterization of the C. formosensis diterpene synthases (CfdiTPSs), which participate in skeleton formation and differentiation of diterpenes. In this study, we identified eight diTPSs from C. formosensis transcriptome, and they all contain either class I or class II motif, which indicates they are all monofunctional enzymes. These candidates consist of three class II diTPSs and five class I diTPSs, and after conducting in vivo and in vitro assays, class II diTPS CfCPS1 was characterized as a (+)-copalyl diphosphate synthase ((+)-CPS), and class I diTPSs CfKSL1 could further convert (+)-copalyl diphosphate ((+)-CPP) to levopimaradiene. Meanwhile, CfKSL1 also accepted labda-13-en-8-ol diphosphate (LPP) as substrate and formed monoyl oxide. Another class I diTPS, CfKSL4, exhibits a strong enzymatic ability of isoabienol synthase, which is firstly reported in conifer. This finding provides potential participants in the biosynthesis of unique diterpenoids, and with this knowledge, we can further expand our understanding of diterpenoid metabolism in Cupressaceae and their potential role in plant defense.

Seasonal variations in emission rates and composition of terpenoids emitted from Chamaecyparis formosensis (Cupressaceae) of different ages

Chamaecyparis formosensis (Cupressaceae) is among the most precious endemic conifers in Taiwan. Field study was conducted on seasonal variations in emission rates and compositions of terpenoids from this tree species of two different ages. A total of 21 terpenoids were detected, of which there were 13 monoterpenoids (MTs), 4 sesquiterpenoids (STs), and 4 diterpenoids (DTs). MTs dominated the emissions in both saplings and adult trees and produced more than 80% of terpene emissions. Contrasting seasonal pattern between saplings and adult trees was found. Total actual emissions from saplings were higher in cold seasons (range, 64.40 ± 13.18 to 140.74 ± 18.90 ng g^-1 h^-1) than in warm seasons (range, 55.63 ± 15.84 to 63.48 ± 11.85 ng g^-1 h^-1). Photosynthetically active radiation (PAR) was found to be the most important factor affecting terpene emissions from saplings. On the contrary, higher emissions were found in warm seasons for adult trees (range, 101.49 ± 12.29 to 181.35 ± 80.15 ng g^-1 h^-1), and the emissions were mainly in response to temperature. Some compounds in C. formosensis of both ages (e.g., β-myrcene, α-terpinene, trans-β-ocimene, terpinen-4-ol, α-cedrene and trans-β-farnesene) showed comparably higher contents in cold seasons. Results presented here provide important fundamental information for better understanding of forest bathing and estimating air quality in Taiwan.

Estimation of phloem carbon translocation belowground at stand level in a hinoki cypress stand

At stand level, carbon translocation in tree stems has to match canopy photosynthesis and carbohydrate requirements to sustain growth and the physiological activities of belowground sinks. This study applied the Hagen-Poiseuille equation to the pressure-flow hypothesis to estimate phloem carbon translocation and evaluate what percentage of canopy photosynthate can be transported belowground in a hinoki cypress (Chamaecyparis obtusa Sieb. et Zucc.) stand. An anatomical study revealed that, in contrast to sieve cell density, conductive phloem thickness and sieve cell hydraulic diameter at 1.3 m in height increased with increasing tree diameter, as did the concentration of soluble sugars in the phloem sap. At tree level, hydraulic conductivity increased by two orders of magnitude from the smallest to the largest trees in the stand, resulting in a stand-level hydraulic conductance of 1.7 × 10-15 m Pa-1 s-1. The osmotic potential of the sap extracted from the inner bark was -0.75 MPa. Assuming that phloem water potential equalled foliage water potential at predawn, the turgor pressure in the phloem at 1.3 m in height was estimated at 0.22 MPa, 0.59 MPa lower than values estimated in the foliage. With this maximal turgor pressure gradient, which would be lower during day-time when foliage water potential drops, the estimated stand-level rate of carbon translocation was 2.0 gC m-2 day-1 (30% of daily gross canopy photosynthesis), at a time of the year when aboveground growth and related respiration is thought to consume a large fraction of photosynthate, at the expense of belowground activity. Despite relying on some assumptions and approximations, this approach, when coupled with measurements of canopy photosynthesis, may further be used to provide qualitative insight into the seasonal dynamics of belowground carbon allocation.

Distribution of coniferin in differentiating normal and compression woods using MALDI mass spectrometric imaging coupled with osmium tetroxide vapor treatment

Matrix-assisted laser desorption/ionization mass spectrometric imaging (MALDI-MSI) was employed to detect monolignol glucosides in differentiating normal and compression woods of two Japanese softwoods, Chamaecyparis obtusa and Cryptomeria japonica Comparison of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry collision-induced dissociation fragmentation analysis and structural time-of-flight (MALDI-TOF CID-FAST) spectra between coniferin and differentiating xylem also confirmed the presence of coniferin in differentiating xylem. However, as matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and MALDI-TOF CID-FAST spectra of sucrose were similar to those of coniferin, it was difficult to distinguish the distribution of coniferin and sucrose using MALDI-MSI and collision-induced dissociation measurement only. To solve this problem, osmium tetroxide vapor was applied to sections of differentiating xylem. This vapor treatment caused peak shifts corresponding to the introduction of two hydroxyl groups to the C=C double bond in coniferin. The treatment did not cause a peak shift for sucrose, and therefore was effective in distinguishing coniferin and sucrose. Thus, it was found that MALDI-MSI combined with osmium tetroxide vapor treatment is a useful method to detect coniferin in differentiating xylem.

Environmental consequences of uranium atmospheric releases from fuel cycle facility: II. The atmospheric deposition of uranium and thorium on plants

Uranium and thorium isotopes were measured in cypress leaves, wheat grains and lettuce taken in the surroundings of the uranium conversion facility of Malvési (South of France). The comparison of activity levels and activity ratios (namely (238)U/(232)Th and (230)Th/(232)Th) in plants with those in aerosols taken at this site and plants taken far from it shows that aerosols emitted by the nuclear site (uranium releases in the atmosphere by stacks and (230)Th-rich particles emitted from artificial ponds collecting radioactive waste mud) accounts for the high activities recorded in the plant samples close to the site. The atmospheric deposition process onto the plants appears to be the dominant process in plant contamination. Dry deposition velocities of airborne uranium and thorium were measured as 4.6 × 10(-3) and 5.0 × 10(-3) m s(-1), respectively.

Relative deposition of xylan and 8-5'-linked lignin structure in Chamaecyparis obtusa, as revealed by double immunolabeling by using monoclonal antibodies

Immunolabeling by using monoclonal antibodies showed that xylan deposition precedes the formation of 8-5'-linked structure of lignin in normal and compression woods of Chamaecyparis obtusa. Xylan deposition and formation of 8-5'-linked lignin structure in differentiating xylems from normal and compression woods in Chamaecyparis obtusa were examined by immunoelectron microscopy using monoclonal antibodies (LM10 or LM11) to detect xylan localization. The 8-5'-linked lignin structure was immunolocalized using KM1 antibody. Xylan and 8-5'-linked lignin double immunolabeling was performed using secondary antibodies labeled with colloidal gold particles of different diameters. In normal wood, KM1 labeling occurred in the compound middle lamella (CML) and S1 layer during S1 layer formation and increased as S2 and S3 layers formed, with labeling occurring at the outer part of the previous layer. In compression wood, mild KM1 labeling occurred in the CML and outer part of the S1 layer at the later S1 layer formation stage, with increased labeling as the S2 layer formed. Minor labeling occurred in the outer part of the S2 layer during helical cavity formation. Comparison between KM1 labeling and KMnO4 staining suggested that lignin other than 8-5'-linked structure was formed during early lignification, and the proportion of 8-5'-linked lignin structure increased at later stages of lignification in both normal and compression woods. LM10 and LM11 labeling occurred slightly earlier than KM1 labeling, suggesting that xylan deposition preceded the formation of 8-5'-linked lignin in normal and compression woods. Less labeling by KM1, LM10, and LM11 occurred in the outer part of the S2 layer in compression wood, which has abundant lignin. Thus, lignin in these parts is composed of lignin substructures other than the 8-5' linkage.

Vertical distribution of radiocesium in coniferous forest soil after the Fukushima nuclear power plant accident

This study deals with the description of the vertical distribution of radiocaesium ((137)Cs and (134)Cs) in a representative coniferous forest soil, investigated 10 months after the Fukushima radioactive fallout. During soil sampling, the forest floor components (understory plants, litter (Ol-) and fermented layers (Of)) were collected and treated separately. The results indicate that radiocesium is concentrated in the forest floor, and high radiocesium transfer factor observed in the undergrowth plants (3.3). This made the forest floor an active exchanging interphase for radiocesium. The raw organic layer (Ol + Of) holds 52% (5.3 kBq m(-2)) of the Fukushima-derived and 25% (0.7 kBq m(-2)) of the pre-Fukushima (137)Cs at the time of the soil sampling. Including the pre-Fukushima (137)Cs, 99% of the total soil inventory was in the upper 10 cm, in which the organic matter (OM) content was greater than 10%, suggesting the subsequent distribution most likely depends on the OM turnover. However, the small fraction of the Fukushima-derived (137)Cs at a depth of 16 cm is most likely due to the infiltration of radiocesium-circumscribed rainwater during the fallout before that selective adsorption prevails and reduces the migration of soluble (137)Cs. The values of the depth distribution parameters revealed that the distribution of the Fukushima-derived (137)Cs was somewhat rapid.

Immunolocalization of 8-5' and 8-8' linked structures of lignin in cell walls of Chamaecyparis obtusa using monoclonal antibodies

Mouse monoclonal antibodies were generated against dehydrodiconiferyl alcohol- or pinoresinol-p-aminohippuric acid (pAHA)-bovine serum albumin (BSA) conjugate as probes that specifically react with 8-5' or 8-8' linked structure of lignin in plant cell walls. Hybridoma clones were selected that produced antibodies that positively reacted with dehydrodiconiferyl alcohol- or pinoresinol-pAHA-BSA and negatively reacted with pAHA-BSA and guaiacylglycerol-beta-guaiacyl ether-pAHA-BSA conjugates containing 8-O-4' linkage. Eight clones were established for each antigen and one of each clone that positively reacted with wood sections was selected. The specificity of these antibodies was examined by competitive ELISA tests using various lignin dimers with different linkages. The anti-dehydrodiconiferyl alcohol antibody reacted specifically with dehydrodiconiferyl alcohol and did not react with other model compounds containing 8-O-4', 8-8', or 5-5' linkages. The anti-pinoresinol antibody reacted specifically with pinoresinol and syringaresinol and did not react with the other model compounds containing 8-O-4', 8-5', or 5-5' linkages. The antibodies also did not react with dehydrodiconiferyl alcohol acetate or pinoresinol acetate, indicating that the presence of free phenolic or aliphatic hydroxyl group was an important factor in their reactivity. In sections of Japanese cypress (Chamaecyparis obtusa), labeling by the anti-dehydrodiconiferyl alcohol antibody was found in the secondary walls of phloem fibers and in the compound middle lamellae, and secondary walls of tracheids. Weak labeling by the anti-pinoresinol antibody was found in secondary walls of phloem fibers and secondary walls and compound middle lamellae of developed tracheids. These labelings show the localization of 8-5' and 8-8' linked structure of lignin in the cell walls.

A conifer ABI3-interacting protein plays important roles during key transitions of the plant life cycle

ABI3 (for ABSCISIC ACID INSENSITIVE3), a transcription factor of the abscisic acid signal transduction pathway, plays a major role during seed development, dormancy inception, and dormancy maintenance. This protein appears to also function in meristematic and vegetative plant tissues and under certain stress conditions. We have isolated the ABI3 gene ortholog (CnABI3) from yellow cedar (Callitropsis nootkatensis) and found that it was functionally similar to other ABI3 genes of angiosperms. Here, we report that using a yeast (Saccharomyces cerevisiae) two-hybrid approach, we have identified another protein of yellow cedar (CnAIP2; for CnABI3 INTERACTING PROTEIN2) that physically interacts with CnABI3. Functional analyses revealed that CnAIP2 plays important roles during key transitions in the plant life cycle: (1) CnAIP2 impaired seed development and reduced seed dormancy; (2) CnAIP2 promoted root development, particularly the initiation of lateral roots, and the CnAIP2 gene promoter was exquisitely auxin sensitive; and (3) CnAIP2 promoted the transition from vegetative growth to reproductive initiation (i.e. flowering). The nature of the effects of CnAIP2 on these processes and other evidence place CnAIP2 in the category of a "global" regulator, whose actions are antagonistic to those of ABI3.

The natural abundance of 15N in plant and soil-available N indicates a shift of main plant N resources to NO3(-) from NH4(+) along the N leaching gradient

To investigate which of ammonium (NH(4)(+)) or nitrate (NO(3)(-)) is used by plants at gradient sites with different nitrogen (N) availability, we measured the natural abundance of (15)N in foliage and soil extractable N. Hinoki cypress (Chamaecyparis obtusa Endlicher) planted broadly in Japan was selected for use in this study. We estimated the source proportion of foliar N (NH(4)(+) vs. NO(3)(-)) quantitatively using mass balance equations. The results showed that C. obtusa used mainly NH(4)(+) in N-limited forests, although the dependence of C. obtusa on NO(3)(-) was greater in other NO(3)(-)-rich forests. We regarded dissolved organic N (DON) as a potential N source because a previous study demonstrated that C. obtusa can take up glycine. Thus we added DON to our mass balance equations and calculated the source proportion using an isotope-mixing model (IsoSource model). The results still showed a positive correlation between the calculated plant N proportion of NO(3)(-) and the NO(3)(-) pool size in the soil, indicating that high NO(3)(-) availability increases the reliance of C. obtusa on NO(3)(-). Our data suggest the shift of the N source for C. obtusa from NH(4)(+) to NO(3)(-) according to the relative availability of NO(3)(-). They also show the potential of the foliar delta(15)N of C. obtusa as an indicator of the N status in forest ecosystems with the help of the delta(15)N values of soil inorganic and organic N.

Relationships among plants, soils and microbial communities along a hydrological gradient in the New Jersey Pinelands, USA

BACKGROUND AND AIMS

Understanding the role of different components of hydrology in structuring wetland communities is not well developed. A sequence of adjacent wetlands located on a catenary sequence of soils and receiving the same sources and qualities of water is used to examine specifically the role of water-table median position and variability in affecting plant and microbial community composition and soil properties.

METHODS

Two replicates of three types of wetland found adjacent to each other along a hydrological gradient in the New Jersey Pinelands (USA) were studied. Plant-community and water-table data were obtained within a 100-m(2) plot in each community (pine swamp, maple swamp and Atlantic-white-cedar swamp). Monthly soil samples from each plot were analysed for soil moisture, organic matter, extractable nitrogen fractions, N mineralization rate and microbial community composition. Multivariate ordination methods were used to compare patterns among sites within and between data sets.

KEY RESULTS

The maple and pine wetlands were more similar to each other in plant community composition, soil properties and microbial community composition than either was to the cedar swamps. However, maple and pine wetlands differed from each other in water-table descriptors as much as they differed from the cedar swamps. All microbial communities were dominated by Gram-positive bacteria despite hydrologic differences among the sites. Water-table variability was as important as water-table level in affecting microbial communities.

CONCLUSIONS

Water tables affect wetland communities through both median level and variability. Differentiation of both plant and microbial communities are not simple transforms of differences in water-table position, even when other hydrologic factors are kept constant. Rather, soil genesis, a result of both water-table position and geologic history, appears to be the main factor affecting plant and microbial community similarities.

Deposition and solubility of airborne metals to four plant species grown at varying distances from two heavily trafficked roads in London

In urban areas, a highly variable mixture of pollutants is deposited as particulate matter. The concentration and bioavailability of individual pollutants within particles need to be characterised to ascertain the risks to ecological receptors. This study, carried out at two urban parks, measured the deposition and water-solubility of metals to four species common to UK urban areas. Foliar Cd, Cr, Cu, Fe, Ni, Pb and Zn concentrations were elevated in at least one species compared with those from a rural control site. Concentrations were, however, only affected by distance to road in nettle and, to a lesser extent, birch leaves. Greater concentrations of metal were observed in these species compared to cypress and maple possibly due to differences in plant morphology and leaf surfaces. Solubility appeared to be linked to the size fraction and, therefore, origin of the metal with those present predominantly in the coarse fraction exhibiting low solubility.

Can fog contribute to the nutrition of Chamaecyparis obtusa var. formosana? Uptake of a fog solute tracer into foliage and transport to roots

Yellow cypress (Chamaecyparis obtusa (Siebold & Zucc.) Endl. var. formosana (Hayata) Rehder) is the predominant tree species of Taiwan's nutrient-poor, mountain fog forests. Little is known about the potential contribution of solute uptake from fog to the overall nutrition of these trees. Shoots of yellow cypress seedlings were misted with artificial fog containing the tracer rubidium (Rb) in laboratory and field experiments to determine if there is solute uptake from the fog. After misting shoots for six weeks, substantial amounts of tracer were detected in unexposed roots by inductively coupled plasma mass spectroscopy bulk analysis. Possible routes of entry were examined by element imaging with energy dispersive X-ray analysis. Direct uptake of the tracer into leaves across the cuticle and epidermis was small, excluding this as the major uptake path. Accumulations of Rb were found on leaf surfaces along the edges of the leaves. The almost daily changes in fog coverage and air humidity may enhance the accumulation of fog solutes at leaf edges. Accumulation of Rb was also found in narrow clefts between opposite leaves and between the outermost and underlying alternating stacked leaves. The clefts provide a direct passage from the leaf surface to the space beneath the imbricate leaves and the underlying alternate leaves, possibly facilitating solute uptake from fog, which in turn may contribute to the nutrition of yellow cypress.

Dynamics of heterorhizic root systems: protoxylem groups within the fine-root system of Chamaecyparis obtusa

To understand the physiology of fine-root functions in relation to soil organic sources, the heterogeneity of individual root functions within a fine-root system requires investigation. Here the heterogeneous dynamics within fine-root systems are reported. The fine roots of Chamaecyparis obtusa were sampled using a sequential ingrowth core method over 2 yr. After color categorization, roots were classified into protoxylem groups from anatomical observations. The root lengths with diarch and triarch groups fluctuated seasonally, whereas the tetrarch root length increased. The percentage of secondary root mortality to total mortality increased with increasing amounts of protoxylem. The carbon : nitrogen ratio indicated that the decomposability of primary roots might be greater than that of secondary roots. The position of diarch roots was mostly apical, whereas tetrarch roots tended to be distributed in basal positions within the root architecture. We demonstrate the heterogeneous dynamics within a fine-root system of C. obtusa. Fine-root heterogeneity should affect soil C dynamics. This heterogeneity is determined by the branching position within the root architecture.

Linking deer browsing and terpene production among genetic identities in Chamaecyparis nootkatensis and Thuja plicata (Cupressaceae)

To investigate whether differential herbivore browsing reflects genetic variation in plant defense expression, variation in needle terpenes and damage caused by black-tailed deer (Odocoileus hemionus) was analyzed on yellow-cedar (Chamaecyparis nootkatensis) and western redcedar (Thuja plicata). In a 100-genet yellow-cedar population, three genets that were heavily browsed and had extremely low levels of monoterpenes (0-0.36% dry matter), sesquiterpenes, and diterpenes were compared to unbrowsed genets (0.85-3.83% monoterpenes in dry matter). These differences were maintained in individuals protected from browsing, suggesting genetically based variation in constitutive terpene production. In western redcedar, heavily browsed trees had significantly lower total monoterpene concentrations (1.69% dry matter) than lightly browsed trees (3.32% dry matter). One heavily browsed tree expressed no monoterpenes. No differences were found for diterpenes. In both species, the genotypes with extremely low monoterpene concentrations came from the same open-pollinated families.