AFLP fingerprinting of elite varieties (clones) from the genus Populus

Accurate identification of varieties (clones) and knowledge of their genetic relationships are essential for poplar breeding and variety management. In this study, 21 elite poplar varieties of Tacamahaca and Aigeiros in China were fingerprinted using amplified fragment length polymorphism (AFLP) markers. Four AFLP primer pairs developed generated totally 181 AFLP polymorphic fragments, and in particular, each primer pair generated fingerprint profiles specific to each of the tested varieties. The genetic relationships among the varieties were evaluated by dendrograms and multidimensional scaling (MDS). The results showed that the tested poplar can be classified into five groups, and indicated the clear separation of varieties of different sections of poplar and the primary distinction between native and exotic poplar varieties. This study indicated that tested poplar varieties could be identified by their fingerprint profiles and that genetic relationships deduced from the study were consistent with their genealogy. In addition, our results demonstrated that AFLP could be used to construct DNA fingerprints of polar clones at a large-scale level and to determine genetic relationships of poplar varieties. __________ Translated from Acta Botanica Yunnanica, 2006, 28(1): 85–90 [译自: 云南植物研究]     

Drought stress tolerance analysis of Populus ussuriensis clones with different ploidies

The selection of drought-tolerant plants is an important aspect of plant breeding.We studied physiological and biochemical mechanisms of different ploidies of Populus ussuriensis Kom.that relate to drought stress tolerance.We used a 5%(v/v)polyethylene glycol(PEG-6000)solution to simulate drought stress.We recorded leaf phenotypes including color,dry area and curl degree.We evaluated sequential variations in some drought stress tolerance-related physiological and biochemical indices and compared these among diploid clones(CK),triploid clones(T12)and tetraploid clones(F20).T12 leaves exhibited slightly more drought stress damage than CK and F20 leaves.CK leaves suffered the most severe drought stress damage.The physiological and biochemical indices of the different ploidies differed significantly 12 days after drought stress treatment.The activities of superoxide dismutase,peroxidase,catalase and proline in the triploid(T12)leaves were the highest.The relative electric conductivity and malondialdehyde content of T12 leaves were the lowest.The index values of F20 were between those ofthe diploid and triploid.In consideration of these results,the drought resistance of the three different ploidies of P.ussuriensis can be ranked as T12>F20>CK.We speculate that the gene expression patterns of polyploid clones of poplar will change after genome doubling and that some of the drought stress tolerance-related physiological and biochemical indices will be improved,resulting in greater drought tolerance of polyploid clones.     

Gas exchange characteristics of Populus trichocarpa, Populus deltoides and Populus trichocarpa x P. deltoides clones

Responses of net photosynthesis, dark respiration, photorespiration, transpiration, and stomatal conductance to irradiance, temperature, leaf-to-air vapor density difference (VDD), and plant water stress were examined in two Populus trichocarpa clones (one from a moist, coastal climate in western Washington and one from a dry, continental climate in eastern Washington), one P. deltoides clone, and two P. trichocarpa x P. deltoides clones. Light saturation of photosynthesis in greenhouse-grown trees occurred at about 800 micromol m(-2) s(-1) for P. deltoides, P. trichocarpa x P. deltoides, and the eastern Washington ecotype of P. trichocarpa, but at about 600 micromol m(-2) s(-1) for the western Washington ecotype of P. trichocarpa. Average net photosynthesis (at saturating irradiance and the optimum temperature of 25 degrees C) was 20.7, 18.8, 18.2 and 13.4 micromol CO(2) m(-2) s(-1) for P. deltoides, P. trichocarpa x P. deltoides, and the eastern and western Washington clones of P. trichocarpa, respectively. In all clones, net photosynthesis decreased about 14% as VDD increased from 3 to 18 g H(2)O m(-3). Stomatal conductance decreased sharply with decreasing xylem pressure potential (XPP) in all clones except the western Washington clone of P. trichocarpa. Stomata in this clone were insensitive to changes in XPP and did not control water loss. Complete stomatal closure (stomatal conductance < 0.05 cm s(-1)) occurred at about -2.0 MPa in the eastern Washington clone of P. trichocarpa and around -1.25 MPa in the P. deltoides and P. trichocarpa x P. deltoides clones. Transpiration rates were highest in the P. trichocarpa x P. deltoides clone and lowest in the western Washington clone of P. trichocarpa. The P. deltoides clone and eastern Washington clone of P. trichocarpa had the highest water use efficiency (WUE) and the western Washington clone of P. trichocarpa had the lowest WUE. The hybrids were intermediate. It was concluded that: (1) gas exchange characteristics of eastern and western Washington clones of P. trichocarpa reflected adaptation to their native environment; (2) crossing the western Washington clone of P. trichocarpa with the more drought resistant P. deltoides clone produced plants better adapted to the interior Pacific Northwest climate, although the stomatal response to soil water deficits in the hybrid was conservative compared with that of the eastern Washington clone of P. trichocarpa; and (3) introducing eastern Washington clones of black cottonwood into breeding programs is likely to yield lines with favorable growth characteristics combined with enhanced WUE and adaptation to soil water deficits.     

四种杨属植物的热值及灰分含量的比较

对新疆克拉玛依地区的胡杨(P.euphraticaOliv.)、俄罗斯杨(Populus.Russkii)、新疆杨(P.albavar.pyramidalis)、银×新杨(Populus alba×Populus bolleana),茎、枝、根热值和灰分含量进行研究。结果表明:(1)4种杨属植物不同组分灰分含量变化趋势没有一定的规律性,但各组分皮的灰分含量均大于木质的灰分含量;(2)4种杨属植物不同组分的干质量热值和去灰分热值变化相同,均为枝茎根;(3)4种杨属植物不同部位木质的干重热值和灰分含量没有显著的线性相关(P0.01),不同部位皮的干重热值和灰分含量具有显著的线性相关(P0.01);(5)4种杨属植物热值各组分木质和皮的差异不显著(P0.01)。     

Diversity of leaf traits related to productivity in 31 Populus deltoides x Populus nigra clones

To test if some leaf parameters are predictors of productivity in a range of Populus deltoides (Bartr.) Marsh. x P. nigra L. clones, we assessed leaf traits and productivity in 2-month-old rooted cuttings from 31 clones growing in 4-l pots in a greenhouse, under conditions of controlled temperature and optimal irrigation. We evaluated four groups of variables describing (1) productivity (total biomass), (2) leaf growth (total leaf number increment and total leaf area increment rate), (3) leaf structure (specific leaf area and nitrogen and carbon contents) and (4) carbon isotope discrimination (delta), which is negatively correlated with time-integrated water-use efficiency. High-yielding clones did not necessarily display high leaf growth rates, but they displayed a larger total leaf area, lower specific leaf area and lower leaf nitrogen concentration than clones with low productivity. Total leaf area was mainly controlled by maximal individual leaf area and total leaf area increment rate (r = 0.51 and 0.56, respectively). Carbon isotope discrimination did not correlate with total biomass, but it was associated with total number of leaves and total leaf area increment rate (r = 0.39 and 0.45, respectively). Therefore, leaf area and specific leaf area were better indicators of productivity than leaf growth traits. The observed independence of delta from biomass production provides opportunities for selecting poplar clones combining high productivity and high water-use efficiency.     

三倍体毛白杨品种和种植密度对其叶片营养元素含量的影响

在田间试验条件下,采用裂区设计,以三倍体毛白杨无性系S1、S6、S8、S11为试验材料,以二倍体毛白杨S10为对照,采用7种种植密度A1(2 m×2 m)、A2(2 m×3 m)、A3(2 m×3.5 m)、A4(3 m×4 m)、A5(2 m×4 m)、A6(2 m×5 m)、A7(3 m×3 m),研究了不同品种和种植密度对三倍体毛白杨叶片营养元素含量的影响。结果表明:不同的无性系对三倍体毛白杨叶片中N、P、K、Ca、Mg的含量均有极显著的影响。叶片中N含量最高的是S6(27.41 g/kg),P含量最高的是S1(1.88 g/kg),K含量最高的是S8(3.59 g/kg),Ca、Mg含量最高的分别是S10(10.48 g/kg)、S11(4.61 g/kg)。不同种植密度对叶片中N元素的含量有显著的影响,其中叶片含N量最多的是A6,达26.97 g/kg。而不同种植密度的无性系叶片中P、K、Ca、Mg的含量无显著差异。相关性分析表明,各元素之间存在一定的相关性,Mg与Ca之间呈显著正相关,与K之间呈显著负相关。     

Variation in juvenile traits of natural black poplar (Populus nigra L.) clones in Turkey

Natural black poplar (Populus nigra L.) clones sampled from river courses were tested in the arid southeast region of Turkey, using a randomized complete block field design with four replications. Clones were laid out in row plots of eight ramets each. Height and apical dominance were assessed at age one year; diameter, survival, bole straightness and branchiness were measured at age two years. Clones differed significantly in survival, growth and quality traits. The results showed that promising clones exist in natural populations. Two commercial clones out of four did not grow as fast as the top new selection clones. For bole straightness, three commercial clones had significantly lower grading scores than the top best 14 clones. Principal components analysis indicated that growth, apical dominance and branching are the most important traits distinguishing black poplar clones. Diameter had a moderate correlation (0.34) with bole straightness. Relationships between geographic variables (elevation, latitude and longitude) with growth and stem quality traits were weak. Considerable genetic variation was observed among clones for all the traits. Genetic differences among the clones accounted for 27% (survival, bole straightness) to 39% (height) of the total variance. Broad-sense individual heritability ranged from 0.27 (survival) to 0.37 (apical dominance). Clonal mean heritabilities were higher than individual heritabilities and ranged from 0.60 (survival) to 0.82 (diameter), implying considerable gain could be realized via selective improvement methods.     

Characterization and identification of leaf morphology of Populus deltoides Bartr.clones

Leaves are of fundamental importance to plants,representing their facility to generate power and are the sensing units of plants towards the environment.An attempt was made to characterize and compare the variations of leaf morphology of various Populus deltoides Bartr.clones by studying the winter buds and other leaf parameters of fully developed leaves.To achieve these objectives,forty-three exotic and indigenous clones of P.deltoides Bartr.were evaluated for different parameters.On the basis of various morphological characteristics the results reveal that each clone has a distinct color pattern of leaves.Different colors observed in these clones varied from light green through green to dark green.Two distinct lengths of the leaf apex were found,i.e.,short and long; as well both acuminate and acute apex types were found.Erratic distribution of serration of leaves was also found.In this study,the morphological traits of leaves provided discriminatory grounds for separating various populations of P.deltoides Bartr.clones.Winter bud studies indicate that different clones vary considerably with regard to shape,color,shape of leaf scars and exudation.     

Comparison and early selection of new clones in Populus tomentosa

In our study, two experimental plantations, respectively, with 24 and 32 new clones of P. tomentosa, were established in Weixian County, Hebei Province and Wuzhi County, Henan Province using a completely randomized block design. A comparative study was conducted on the continuous 5-year-old height and diameter at breast height (DBH) of new clones in the two plantations. As well, based on genetic correlation over the years of testing of these clones, a preliminary study of early selection was carried out. Results indicate that the growth traits of the new clones in Weixian were better than those in Wuzhi The traits show weak correlation between the two plantations. In some stands, the height, DBH and seedling volume of 5-year-old clones presented statistically sig-nificant differences among clones. In both plantations, the new clones showed over 0.6 repeatability of beight, DBH and volume, as well as larger coefficients of variation (CV). The fact that these clones achieved the largest repeatability and CV in the second year suggests that these traits are highly controlled by heredity. Thus, based on the growth traits of the second year, the new clones B305, B307, B303, H75, BT18, BTI7 and 21J-1 were considered suitable in Weixian. hi Wuzhi, the new clones had variable repeatability and CVs in various years and their correlation of growth traits among different years was not high. We conclude that early selection of new clones was not feasible in Wuzhi.     

大叶山杨优良无性系组培育苗技术

大叶山杨(Populus davidianavar·macrophylla)是适合我国北方林区营造速生丰产林的优良树种,但因其扦插难生根,所以很难进行无性繁殖,加之其种子不易采集,也很难满足大量生产的要求。利用组织培养技术,不受上述条件的制约,可在短期内建立繁殖体系,不仅保存了优良的种质资源,也     

Differential physiological and morphological responses of two hybrid Populus clones to water stress

Hardwood cuttings of Populus clones Tristis #1 and Eugenei were grown in pots in a controlled environment chamber to observe early patterns of growth and water relations in response to changing conditions of water stress. Height and dry weight growth, dry matter partitioning, leaf area production, stomatal conductance and leaf water potential were measured periodically during the 73-day experiment. The two clones reacted in a similar way to an initial period of stress, showing reduced growth, stomatal conductance and leaf water potential. However, when stress was interrupted by ample watering and then reimposed, substantial differences between the clones were evident. Growth of Eugenei fully recovered after stress was relieved, especially leaf growth, but when water deficiency was reimposed, the plants wilted and some leaves died. Tristis #1, in contrast, showed a greater adaptation to changing stress conditions; it grew less than Eugenei after drought was interrupted, but showed little adverse effect of renewed water deficits. These responses were partially explained by the higher root/leaf weight ratios of Tristis #1 which enabled it to maintain a more favorable plant water status than Eugenei.     

毛白杨新无性系引进选育研究

对引进11个毛白杨新无性系，在造林试验获取各无性系生长、形质指标，以及抗病性状等数据基础上，进行了多性状选择。结果BT17、51L-7、193、175、196、BT18、BT85等7个新无性系生长快、不蹲苗、破腹病率低，适应性强，材积生长比对照增益180．35％，是大连地区造林优良新品种，其中193、BT17、BT18为雄性不飞絮无性系，又是城镇绿化的好品种。     

杨属地理分布与起源初探

本文讨论了杨属的属下分类群；对各组的特征进行了比较；分析了各组及种类在世界及中国的分布。本文运用化石、古地理、古气候、孢粉区系、现代地理分布等证据对杨属的起源时间及地点进行了分析，认为杨属可能起源于晚白垩纪时的中国西南部和中部地区；最后讨论了杨属起源后的散布途径及现代分布格局的成因。     

湘林黑杨新无性系不同部位水培生根性状研究

对湘林-90等6个杨树新无性系及中汉-17、I-69杨1年生苗,自下而上按4部位分别裁截插穗,进行水培生根试验,探索杨树水培后皮层凸起、先期不定根数量、凸起成根率及根长在无性系、区分段间的分布规律及相关性。     

Response of clones of Eucalyptus microtheca to NaCl in vitro

We studied the response of nodal segments of Eucalyptus microtheca F.J. Muell. to salt stress in a tissue culture system. Three clones of Eucalyptus microtheca (37, 42 and 43) were grown in vitro under saline conditions (0-140 mM NaCl) for three months. The survival of all three clones decreased with increasing concentrations of NaCl in the medium, but the presence of up to 70 mM NaCl stimulated rooting in Clones 37 and 42. Shoot elongation of Clone 43 was less affected by salt than that of Clones 37 and 42. Leaf growth, expressed as leaf length, was stimulated 40% in Clone 42 and 33% in Clone 43, but was progressively inhibited up to 27% by 70 mM NaCl in Clone 37. Massive accumulation of Na(+) and Cl(-) occurred, especially in Clones 42 and 43 (4000 and 3000 mmol Na(+) kg(DW) (-1), respectively), as the salinity of the culture solution increased, and this was correlated with inhibition of growth. Because of a reduction in the accumulation of K(+) with increasing salinity, the K(+)/Na(+) ratio decreased from a control value of 4.5 to 0.14 in shoots grown in the presence of 140 mM NaCl. The development of techniques for selecting seedlings by monitoring the physiology of shoots in vitro instead of testing whole plants in vivo will provide a relatively simple method of selection for woody trees.     

杨树优良无性系选择初探

引种杨树无性系进行对比造林试验,对保存率大于70%的7种无性系的生长量和稳定性进行分析评价,结果选择出哲林4号和白林2号杨,抗逆性比较强,生长量也比较高。8年生幼树的胸径生长量达12.4cm和11.6 cm,为对照树种小黑杨的124%和116%;树高为11.7 m和12.1 m,为对照树种的129%和133%。哲林4号和白林2号杨综合评定为优良无性系。     

杨树无性系生长与材性遗传变异及综合选择研究

以6年生18个杨树无性系为材料，研究其生长与材性性状的遗传变异及性状问的相关性，结果表明：除纤维含量、纤维长度外，树高、胸径、材积、纤维宽度、长宽比、木材基本密度6性状在无性系间均存在显著差异，各性状重复力在0．6109～0．9053之间，生长性状受高度遗传控制，纤维宽度、长宽比、木材基本密度受中等至强度遗传控制；生长与材性性状遗传具有相对独立性，就杨树纸浆材而言，材性改良应以生长性状的改良为前提；利用灰色关联度分析法评选出XL-90、XL-77、XL-101、XL-75、XL-92共5个综合性状优异的美洲黑杨杂交新无性系，其中XL-90、XL-77表现尤为突出，与I-69比较，其单株材积生长量分别提高60．71％、46．45％，单株纤维产量分别提高51．43％、44．13％。     

Growth, leaf anatomy, and physiology of Populus clones in response to solar ultraviolet-B radiation

We compared the physiological and morphological responses of rooted cuttings of Populus trichocarpa Torr. & Gray and P. trichocarpa x P. deltoides Bartr. ex Marsh. grown in either near-ambient solar ultraviolet-B (UV-B; 280-320 nm) radiation (cellulose diacetate film) or subambient UV-B radiation (polyester film) for one growing season. Midday biologically effective UV-B radiation was 120.6 and 1.6 mJ m(-2) s(-1) under the cellulose diacetate and polyester films, respectively. Gas exchange, leaf chlorophyll, light harvesting efficiency of photosystem II, and foliar UV-B radiation-absorbing compounds (i.e., flavonoid derivatives) were measured in expanding (leaf plastochron index (LPI) 5), nearly expanded (LPI 10), and fully expanded mature (LPI 15) leaves of intact plants of plastochron index 30 to 35. Plants were then harvested and height, diameter, biomass allocation and leaf anatomical attributes determined. Net photosynthesis, transpiration, and stomatal conductance were significantly greater in mature leaves exposed to subambient UV-B radiation than in mature leaves exposed to near-ambient UV-B radiation. Concentrations of UV-B radiation-absorbing compounds (measured as absorbance of methanol-extracts at 300 nm) were significantly greater in mature leaves exposed to near-ambient UV-B radiation than in mature leaves exposed to subambient UV-B radiation. The UV-B radiation treatments had no effects on chlorophyll content or intrinsic light harvesting efficiency of photosystem II. Height, diameter, and biomass were not significantly affected by UV-B radiation regime in either clone. Leaf anatomical development was unaffected by UV-B radiation treatment in P. trichocarpa x P. deltoides. For P. trichocarpa, leaf anatomical development was complete by LPI 10 in the near-ambient UV-B radiation treatment, but continued through to LPI 15 in the subambient UV-B radiation treatment. Mature leaves of P. trichocarpa were thicker in the subambient UV-B radiation treatment than in the near-ambient UV-B radiation treament as a result of greater development of palisade parenchyma tissue. We conclude that exposure to near-ambient UV-B radiation for one growing season caused shifts in carbon allocation from leaf development to other pools, probably including but not limited to, UV-B absorbing compounds. This reallocation curtailed leaf development and reduced photosynthetic capacity of the plants compared with those in the subambient UV-B radiation treatment and may affect growth over longer periods of exposure.