连作栽培对当归光合参数日变化的影响

利用CI-310 便携式光合作用系统, 测定正茬(连作0 年)、迎茬(隔年连作)、重茬(连作2 年)3 种种植方式下当归叶片的光合参数, 研究其日变化特征。结果表明: 3 种种植方式下当归叶片净光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)和胞间CO₂ 浓度(Ci)的日变化均呈“双峰”曲线, 12:00 时存在明显“午休”现象, 但不同茬口Pn、Tr、Gs 和Ci 高峰和低谷出现的时刻和值不同; 根据Pn、Ci 和Gs 的变化方向, 推测当归叶片的光合“午休”受气孔因素影响; 重茬和迎茬极显著(P<0.01)降低当归叶片叶绿素含量; 正茬种植方式下当归叶片Pn、Gs、Ci 和Tr 的日均值均极显著(P<0.01)和显著(P<0.05)高于重茬。由此得出, 连作栽培显著降低当归叶片的叶绿素含量、Gs、Ci、Pn 和Tr, 进而影响产量形成。     

Optimization of Compatible Mixed Cultures for Liquid State Bioconversion of Municipal Wastewater Sludge

The filamentous fungal strains such as Penicillium corylophilum (P), Aspergillus niger (A), Trichoderma harzianum (T) and Phanerochaete chrysosporium (PC) isolated from its relevant sources (wastewater, sewage sludge and sludge cake) were selected for compatible/incompatible mixed cultures. Six combinations of P. corylophilum and A. niger (P/A); P. corylophilum and P. chrysosporium (P/PC); P. corylophilum and T. harzianum (P/T); A. niger and T. harzianum (A/T); A. niger and P. chrysosporium (A/PC); T. harzianum and P. chrysosporium (T/PC) were used to evaluate their potential performance as compatible/incompatible mixed culture for the treatment of municipal wastewater sludge in a bioconversion process. The results of the present study showed that the combinations of P/A, P/PC and A/PC showed compatible growth and the rest of the combinations (P/T, A/T and T/PC) were incompatible cultures. A maximum production of dry biomass and dry filter cake were recorded in the compatible mixed culture of P. corylophilum and A. niger (P/A). A maximum reduction of COD (90%) and a decreased filtration time of treated sludge was observed in the case of P/A microbial mixed culture. The pH value was also affected by the fungal cultures. Effective results were observed by using microbial mixed culture after four days of treatment compared to other treatments (2 and 6 days).     

Re-sequencing of vrs1 and int-c loci shows that labile barleys (Hordeum vulgare convar. labile) have a six-rowed genetic background

Labile-barleys (Hordeum vulgare convar. labile (Schiem.) Mansf.) are found in the highlands of Ethiopia, Eretria and North India-Pakistan districts. They represent a distinct spike form showing row-type alterations even within individual spikes of the same genotypes. Variation at the six-rowed spike 1 (vrs1) locus is sufficient to control barley lateral spikelet fertility, which is also modified by alleles at the intermedium-c (int-c) locus. This study aimed at re-sequencing these two loci to investigate whether labile-barleys have a two-rowed genetic background, resulting in increased lateral spikelet fertility, or show reduced lateral spikelet fertility if they possess a six-rowed genetic background. The Vrs1 re-sequencing results of 221 supposedly labile-barley accessions from Ethiopia revealed 13 accessions with two novel vrs1.a1 haplotypes. Following the current nomenclature of vrs1 haplotypes, the new haplotypes were named as haplotypes 66 and 67. Re-sequencing at the int-c locus showed that 118 of the labile-barleys possessed the previously described Int-c.a allele but only one accession was found having a novel Int-c.a haplotype in the homozygous state (termed Int-c.a haplotype1; Hap_1). Interestingly, 101 labile-barleys carried the Int-c.a allele and Int-c.a haplotype1 simultaneously, suggesting maintained heterozygosity or recent gene duplication at this locus. Only one accession had a two-rowed haplotype (Vrs1.b3, int-c.b1) and one accession possessed the Vrs1.t (deficiens) and Int-c.a alleles (six-rowed). These two accessions were considered as misclassified labile genotypes and not included in further analysis. Thus, these results confirmed that all of the 219 labile accessions studied in this work showed six-rowed alleles at vrs1 but reduced lateral spikelet fertility. This reduction is most likely caused by the recessive labile (lab) locus which we are in the process to characterize further.     

Single-copy nuclear PolA1 gene sheds light on the origin of S genome with relationships to B and G genomes of polyploid wheat species

PolA1, a single-copy nuclear gene encoding the largest subunit of RNA polymerase I, comprises highly polymorphic intron 19 and nucleotide tag (Ntag) sequences. We analyzed these sequences in 42 accessions, which differed in ploidy, of Triticum–Aegilops and Hordeum species. The lengths of the intron 19 sequences were ca. 110?bp long in Triticum–Aegilops species, except in four Sitopsis species, Ae. longissima, Ae. searsii, Ae. sharonensis, Ae. speltoides, which had introns similar in length to those of Hordeum species, i.e., ca. 240?bp long. Phylogenetic analyses of the Ntag sequences showed that the four Sitopsis and remaining Triticum–Aegilops species were classified into two discrete Hordeum and Triticum clades, respectively. The A and D genome-specific Ntag sequences of polyploid wheats were highly homologous with those of T. urartu and Ae. tauschii, respectively. In Ae. bicornis, another Sitopsis species, two accessions had the short intron 19 and Triticum–type Ntag sequence, which were highly homologous with those of the B genome in polyploid wheats, whereas one accession contained the long intron 19 and Hordeum–type Ntag sequences. In contrast, partial sequence analyses revealed that the three accessions of Ae. bicornis shared highly homology to single-copy DMC1 and EF-G genes. The discrepancy between these results indicates that the Sitopsis species were probably established by hybrid speciation including ancient introgressive hybridization between progenitors of Triticum–Aegilops and Hordeum. Although many researchers have proposed Ae. speltoides as a candidate for the B genome donor, our data suggest the existence of diploid B genome species in the past that were responsible for the origin of both polyploid wheats and Sitopsis species, including Ae. speltoides.     

Comparison of the influences of vegetation stem parameters on hydraulic variables and sediment transport capacity

The hydraulic variables (Hv) and sediment transport capacity (Tc) of overland flow have changed immensely due to large-scale revegetation. However, research comparing the influences of stem parameters (diameter, cover, and arrangement) on Hv and Tc is limited. The objectives of this study were to explore and compare the influences of stem parameters on Hv and Tc. Data on three treatment groups with varying stem diameters, covers, arrangements, flow discharges and slopes were collected in this study. With increasing stem diameter, Hv and Tc increased; Hv included the Reynolds and Froude numbers, flow velocity (v), shear stress (τ), stream power (Ω), and unit stream power (ω). However, the trend of the Darcy-Weisbach friction coefficient (f) was opposite. Hv and Tc were significantly influenced by stem diameter and cover. The effect of stem diameter on Hv and Tc was greater than the effects of cover and arrangement. Stem cover as a variable could not be used to adequately estimate the Tc when there were various stem diameters. A new exponential equation involving stem cover and stem diameter was demonstrated to be an appropriate predictor of Tc. Stem diameter and arrangement had no obvious influence on the relationship between Tc and v, and v as an indicator could explain the effect of stem parameters on Hv and Tc. This result could illustrate why the variables, including v, were able to predict Tc under vegetation stem and litter cover.     

Abundance of Frankia from Gymnostoma spp. in the rhizosphere of Alphitonia neocaledonica,a non-nodulated Rhamnaceae endemicto New Caledonia

The capacity of different soils of New Caledonia to induce nodulation in Gymnostoma poissonianum was studied. The soils were sampled under five Gymnostoma species, Alphitonia neocaledonica (a non-nodulated endemic Rhamnaceae) and Pinus caribea (an introduced species) growing in various ecological conditions. Using G. poissonianum as trap-host, we observed a higher abundance of Frankia from Gymnostoma spp. in the rhizosphere of A. neocaledonica as compared with bare soils and P. caribea rhizosphere. The nodulating capacity of A. neocaledonica rhizosphere was almost similar to that of the five Gymnostoma species (symbiotic host) studied in the same stations. In comparison, bare soils or rhizosphere of P. caribea had poor nodulating capacities. We isolated fourteen Frankia strains from nodules of G. poissonianum after baiting with the rhizospheric soils of five Gymnostoma and A. neocaledonica. Using the PCR/RFLP method, we confirmed the similarity with those already described. Frankia was abundant in the rhizosphere of A. neocaledonica in all the sites studied. One explanation could be a positive tropism of Frankia towards species belonging to families having nodulated species, which is the case of A. neocaledonica endemic in New Caledonia. We can suppose that the non-nodulated plants belonging to these families can excrete some chemical substances able to attract Frankia and to induce its proliferation.     

Infection of wheat seminal roots by varieties of Phialophora radicicola and Gaeumannomyces graminis

The growth of isolates of Phialophora radicicola var. radicicola, P. radicicola var. graminicola, Gaeumannomyces graminis var. graminis, G. graminis var. tritici and Leptosphaeria narmari was compared on the coleoptiles and roots of wheat seedlings. Fungal growth was measured as the extent and density of dark runner hyphae. All except P. radicicola var. graminicola grew on coleoptiles and all grew on roots although only G. graminis var. tritici extensively colonized the root stele. Growth rate on roots was positively correlated with that on agar, P. radicicola var. graminicola and L. narmari growing at about half the rate of the other fungi; hyphal density was high for P. radicicola var. graminicola but relatively low for the other fungi. For P. radicicola var. radicicola, P. radicicola var. graminicola and G. graminis var. tritici growing from buried inocula, the extent and density of hyphae up roots towards the seed was similar to that down, but G. graminis var. tritici caused chocolate-brown stelar discoloration up roots only.Root invasion by P. radicicola var. radicicola, P. radicicola var. graminicola and G. graminis var. tritici was described from sections. Each gave a different pattern of hyphae and host response within an inoculum layer, and progressive changes occurred away from the inoculum. Studies of the rate of penetration by each fungus and the rate and pattern of death of cortical cells explained the differences between fungi. G. graminis var. tritici penetrated living cells in advance of other soil micro-organisms, and hence by hyaline hyphae inducing much lignituber formation as a host resistance reaction. P. radicicola var. graminicola penetrated only senescent or dead cells in association with other soil microorganisms, and hence by dark hyphae, inducing little lignituber formation. P. radicicola var. radicicola was intermediate in all these respects. The high hyphal density of P. radicicola var. graminicola was due to the colonization of cortical cells and spaces by dark, clearly visible, rather than hyaline hyphae, which are invisible in unstained roots. Cell death in the outer cortex explained the observed progressive restriction of growth by all fungi to the inner cortex with increasing distance from the inoculum. Spread by G. graminis var. tritici up roots was ectotrophic relative to the stele but down roots hyphae spread rapidly within the stele. Stelar reactions suggested as resistance mechanisms occurred up roots only. Their absence down roots is attributed to infection disrupting stelar transport.     

Molecular characterization and diversity of puroindoline b-2 variants in cultivated and wild diploid wheat

Cloning and phylogenetic analysis of puroindoline b-2 variants in common wheat (Triticum aestivum L.) and its relatives would advance the understanding of the genetic diversity and evolution of puroindoline b-2 gene in common wheat and its related species. In the present study, common wheat (AABBDD) and four related species, including T. urartu (A^uA^u), Aegilops speltoides (SS), Ae. tauschii (DD), and T. turgidum (AABB) were sampled for the presence of novel alleles at Pinb2v-A1, Pinb2v-B1/Pinb2v-S1 and Pinb2v-D1 loci corresponding to common wheat puroindoline b-2 variants. Nine new alleles were identified at these loci, designated Pinb2v-A1a through Pinb2v-A1c, Pinb2v-S1a through Pinb2v-S1e, and Pinb2v-D1a. Alignment of puroindoline variants or alleles from common wheat and its relatives indicated that all alleles in diploid wheats are attributed to single nucleotide substitution when compared with puroindoline b-2 variants in polyploids. Deduced amino acid sequences showed that all three alleles at Pinb2v-A1 locus and four alleles (Pinb2v-S1a, Pinb2v-S1b, Pinb2v-S1c and Pinb2v-S1e) at the Pinb2v-S1 locus could not be normally translated due to the presence of premature stop codons, whereas Pinb2v-D1a at the Pinb2v-D1 locus and Pinb2v-S1d at the Pinb2v-S1 locus could be normally translated, possibly suggesting that the puroindoline b-2 variant in Ae. tauschii was more highly conserved than those in T. urartu and Ae. speltoides. Meanwhile, puroindoline b-2 variant could be normally translated in all of the durum and common wheat cultivars surveyed. None of the puroindoline b-2 alleles previously identified in durum and common wheat were found in the diploid genome donors examined here, even though a greater diversity of alleles were found in diploid wheat compared to polyploid wheat. These results likely reflect the evolutionary history of tetraploid and hexaploid wheats, although it may be that puroindoline b-2 variant alleles have been selected for stability and functionality in common and durum wheat. This study provides a survey of puroindoline b-2 variants in common wheat and its relatives, and provides useful information for understanding the genetic diversity of puroindoline-like genes and their duplication events in wheat.     

Root-nodule bacteria from indigenous legumes in the north-west of Western Australia and their interaction with exotic legumes

Bacteria were isolated from root-nodules collected from indigenous legumes at 38 separate locations in the Gascoyne and Pilbara regions of Western Australia. Authentication of cultures resulted in 31 being ascribed status as root-nodule bacteria based upon their nodulation of at least one of eight indigenous legume species. The authenticated isolates originated from eight legume genera from 19 sites. Isolates were characterised on the basis of their growth and physiology; 20 isolates were fast-growing and 11 were slow-growing (visible growth within 3 and 7 d, respectively). Fast-growers were isolated from Acacia, Isotropis, Lotus and Swainsona, whilst slow-growers were from Muelleranthus, Rhynchosia and Tephrosia. Indigofera produced one fast-growing isolate and seven slow-growing isolates. Three indigenous legumes (Swainsona formosa, Swainsona maccullochiana and Swainsona pterostylis) nodulated with fast-growing isolates and four species (Acacia saligna, Indigofera brevidens, Kennedia coccinea and Kennedia prorepens) nodulated with both fast- and slow-growing isolates. Swainsona kingii did not form nodules with any isolates. Fast-growing isolates were predominantly acid-sensitive, alkaline- and salt-tolerant. All slow-growing isolates grew well at pH 9.0 whilst more than half grew at pH 5.0, but all were salt-sensitive. All isolates were able to grow at 37 °C. The fast-growing isolates utilised disaccharides, whereas the slow-growing isolates did not. Symbiotic interactions of the isolates were assessed on three annual, one biennial and nine perennial exotic legume species that have agricultural use, or potential use, in southern Australia. Argyrolobium uniflorum, Chamaecytisus proliferus, Macroptilium atropurpureum, Ononis natrix, Phaseolus vulgaris and Sutherlandia microphylla nodulated with one or more of the authenticated isolates. Hedysarum coronarium, Medicago sativa, Ornithopus sativus, Ornithopus compressus, Trifolium burchellianum, Trifolium polymorphum and Trifolium uniflorum did not form nodules. Investigation of the 31 authenticated isolates by polymerase chain reaction with three primers resulted in the RPO1 primer distinguishing 20 separate banding patterns, while ERIC and PucFor primers distinguished 26 separate banding patterns. Sequencing the 16S rRNA gene for four fast- and two slow-growing isolates produced the following phylogenetic associations; WSM1701 and WSM1715 (isolated from Lotus cruentus and S. pterostylis, respectively) displayed 99% homology with Sinorhizobium meliloti, WSM1707 and WSM1721 (isolated from Sinorhizobium leeana and Indigofera sp., respectively) displayed 99% homology with Sinorhizobium terangae, WSM1704 (isolated from Tephrosia gardneri) shared 99% sequence homology with Bradyrhizobium elkanii, and WSM1743 (isolated from Indigofera sp.) displayed 99% homology with Bradyrhizobium japonicum.     

Rhizosphere effect of Galega orientalis in oil-contaminated soil

Randomized lysimeters in an oil-contaminated field contained the following treatments: (1) Galega orientalis seeds inoculated with Rhizobium galegae HAMBI 540, (2) bioaugmentation with Pseudomonas putida PaW85, and (3) R. galegae -inoculated G. orientalis seeds plus bioaugmentation with P. putida PaW85. The bacterial abundance and diversity were analysed in composite samples after one growing season. A total of 208 m-toluate tolerating bacteria were isolated and screened with m-toluate tolerance and utilization tests, and the catechol test. Seventy-nine isolates were characterized with (GTG)₅-PCR genomic fingerprinting and 16S rRNA gene PCR-RFLP ribotyping. Only 10% of the isolated strains were able to degrade m-toluate. Most of the m-toluate utilizing bacteria were catechol positive indicating the existence of a TOL plasmid. Rhizosphere effect of G. orientalis was manifested in oil-contaminated soil. G. orientalis and Pseudomonas bioaugmentation increased the amount of bacteria in oil-contaminated soil. G. orientalis especially together with Pseudomonas bioaugmentation increased the numbers of m-toluate utilizing and catechol positive bacteria in the soil samples indicating an increase in degradation potential. The rhizosphere of G. orientalis increased also the diversity of bacteria. More ribotypes were found in soils treated with G. orientalis and P. putida PaW85 compared to the untreated soil, but the diversity of the m-toluate utilizing bacteria did not significantly increase.     

Collection and evaluation of Hedychium species of Manipur, Northeast India

NE India is considered as one of the centre of diversity of gingers having a total account of 24 species out of the 65 valid species found in the world. Manipur is one of the seven states of NE India with a mere area of 0.7% out of the total area of India. This paper focuses on the distribution, classification and evaluation of Hedychium species collected from Manipur. A total of 11 species were collected, identified and classified based on their morphological characteristics. The species are identified as Hedychium rubrum A.S. Rao et Verma, H. coronarium Koenig, H. chrysoleucum Hook., H. coccineum Buch.-Ham., H. thrysiforme Ker-Gawl., H. flavescens Carey ex Roscoe, H. stenopetalum Lodd., H. urophyllum Lodd., H. marginatum Clarke, H. villosum Wall. and H. elatum R. Brown. Evaluation of its botanical characteristics are also conducted. Analytical hierarchy process method is used in this paper to address the possibility of analysing the potential of these diverse Hedychium resources based on their ornamental, adaptability and utilisation potential which was evaluated on 12 indicator points. H. elatum scored the highest overall index making it the most potential species for sustainable exploitation followed by H. coronarium while H. villosum ranked the lowest.     

Symbiotic relationships and root nodule ultrastructure of the pasture legume Biserrula pelecinus L.—a new legume in agriculture

Biserrula pelecinus is a pasture legume species new to Australian agriculture. The potential N benefit from B. pelecinus pastures in agricultural systems may not be realised if its symbiotic interactions with Mesorhizobium spp. are not well understood. This study evaluated the symbiotic interactions of four strains of Biserrula root-nodule bacteria (WSM1271, WSM1283, WSM1284, WSM1497) with four genotypes of B. pelecinus (cv. Casbah, 93GRC4, 93ITA33, IFBI1) and with a range of related legumes, including species known to be nodulated by strains of Mesorhizobium loti and other Mesorhizobium spp. Structures of root nodules were studied using light and electron microscopy enabling the ultrastructure of effective and ineffective nodules to be compared. B. pelecinus always formed typical indeterminate, finger-like nodules. The number of bacteroids inside symbiosomes varied between host×strain combinations, however, nodules formed by ineffective associations had well developed peribacteroid membranes and abundant bacteroids. Considerable variation was found in N₂-fixing effectiveness of strains isolated from B. pelecinus on the four B. pelecinus genotypes. Strains WSM1271, WSM1284 and WSM1497 nodulated Astragalus membranaceus, only strains WSM1284 and WSM1497 nodulated Astragalus adsurgens. Strain WSM1284 also nodulated Dorycnium rectum, Dorycnium hirsutum, Glycyrrhiza uralensis, Leucaena leucocephala, Lotus edulis, Lotus glaber, Lotus maroccanus, Lotus ornithopodioides, Lotus pedunculatus, Lotus peregrinus, Lotus subbiflorus and Ornithopus sativus. The four strains from B. pelecinus did not nodulate Amorpha fruticosa, Astragalus sinicus, Cicer arietinum, Hedysarum spinosissimum, Lotus parviflorus, Macroptilium atropurpureum or Trifolium lupinaster. M. loti strain SU343 nodulated all four genotypes of B. pelecinus. However, M. loti strain CC829 only nodulated B. pelecinus genotypes 93ITA33 and IFBI1 and the nodules were ineffective. The root nodule isolates from H. spinosissimum (E13 and H4) nodulated B. pelecinus cv. Casbah whereas the commercial inoculant strain for Cicer (CC1192) could not nodulate any genotype of B. pelecinus. These results indicate that strains WSM1271, WSM1283 and WSM1497 isolated originally from B. pelecinus have a specific host range while strain WSM1284 is promiscuous in its capacity to nodulate with a broad range of related species. As B. pelecinus can be nodulated by Mesorhizobium spp. from other agricultural legumes, particularly Lotus, there is an opportunity to utilise this trait in cultivar development.     

Occurrence of both Casuarina-infective and Elaeagnus-infective Frankia strains within actinorhizae of Casuarina collina,endemic to New Caledonia

New Caledonia is characterized by an exceptional concentration of endemic Casuarinaceae species including eight Gymnostoma species and Casuarina collina. Frankia strains isolated from nodules from C. collina have been studied through a range of techniques including molecular typing, infectivity/effectivity and host spectrum. All these isolates had characteristics similar to those of atypical Frankia from Casuarina previously described. This work evidenced several original features within these 26 isolates: (i) they are localized inside the nodule; (ii) they fit into the Elaeagnus-infective Frankia group; (iii) they belonged to four ITS groups already described for Frankia from Gymnostoma. In fact, it is highly probable that atypical Frankia from C. collina and Frankia from Gymnostoma are the same. We can formulate the hypothesis that the Frankia from Gymnostoma could use C. collina as an alternative host in absence of Gymnostoma spp. or when the ecological conditions are favourable to C. collina.     

Community Succession Analysis of Naturally Colonized Plants on Coal Gob Piles in Shanxi Mining Areas, China

Data were collected simultaneously at different succession stages using a space-for-time substitution, and were analyzed using the quantitative classification method (Twinspan) and the ordination technique (DCA). The community succession analysis of naturally colonized plants on coal gob piles in Shanxi mining areas was as followings: Assoc. Setaria viridis + Amaranthus retroflexus → Assoc. Tribulus terrester + Setaria viridis → Assoc. Setaria viridis + Artemisia annua → Assoc. Bothriochloa ischaemum + Artemisia capillaries → Assoc. Bothriochloa ischaemum + Artemisia scoparia → Assoc. Periploca sepium ? Artemisia gmelinii → Assoc. Periploca sepium + Lespedeza daurica ? Artemisia gmelinii → Assoc. Periploca sepium + Vitex negundo var. heterophylla ? Bothriochloa ischaemum → Assoc. Ailanthus altissima ? Lespedeza daurica ? Artemisia gmelinii → Assoc. Robinia pseudoacacia ? Vitex negundo var. heterophylla ? Bothriochloa ischaemum. This established a model of the recovery of natural vegetation on coal gob piles in Shanxi mining areas. The structure, composition and life-forms changed significantly during succession. Six indices of species diversity were used to analyze changes in the richness, evenness and heterogeneity of species during the succession process. As the succession progressed, the richness of plant communities increased significantly, the evenness increased slightly and the heterogeneity increased obviously. The plant development could obviously increase the organic content in the surface layer of coal gob piles. Pioneer species of Setaria viridis, Amaranthus retroflexus, Tribulus terreste, Artemisia gmelinii, Bothriochloa ischaemum, Periploca sepium, Lespedeza daurica, Vitex negundo var. heterophylla, Ailanthus altissima and Robinia pseudoacacia, etc. could colonize successfully and play important roles on the vegetation restoration of coal gob piles.     

外来植物紫茎泽兰入侵对菌根菌群落的影响

为了研究紫茎泽兰(Ageratina adenophora)入侵对土壤菌根真菌(mycorrhizal fungi, MF)群落的影响,采用嵌套PCR 技术分析了外来植物紫茎泽兰入侵生境内土著植物群落、土著植物与紫茎泽兰混生群落、紫茎泽兰单优群落中, 侵染紫茎泽兰及土著植物的MF 群落结构, 及紫茎泽兰与土著植物根围土壤中MF 群落结构。结果表明, 紫茎泽兰不同入侵进程MF 群落结构存在差异, 其中, 从土著植物群落的植物根内检测到内养球囊霉(Glomus intraradices)型克隆; 从土著植物与紫茎泽兰混生群落的紫茎泽兰根内也检测到内养球囊霉型克隆, 而在土著植物根内检测到1 个球囊霉属(Glomus sp 2)型克隆; 从紫茎泽兰单优群落的紫茎泽兰根内未检测到MF, 但从其根围土壤中检测到2 个球囊霉属(Glomus sp 1 和Glomus sp 2)型克隆。在土著植物与紫茎泽兰混生群落中, 从紫茎泽兰根围土壤中检测到4 个克隆型, 分别为毛舌菌阔孢(Trichoglossum hirsutum)、皂味口磨(Tricholoma saponaceum)、亚盖趋本菌(Xylobolus subpileatus)和翘鳞肉齿菌(Sarcodon imbricatus), 从土著植物根围土壤中也检测到4 个克隆型, 分别为小皮伞(Camarophyllopsis hymenocephala)、肉色香蘑(Lepista irina)、皂味口磨及亚侧耳(Panellus serotinus)型克隆; 在土著植物群落中, 从根围土壤只检测到皂味口磨型克隆。紫茎泽兰入侵改变了土著MF 群落结构, 其中在土著植物占据的土壤中以外生菌根真菌为主, 而外来植物紫茎泽兰则更多地积累了丛枝菌根真菌。文中讨论了紫茎泽兰改变入侵地土壤菌根菌群落及其可能对紫茎泽兰入侵的反馈。     

Growth status of rhizobia in relation to their tolerance to low water activities and desiccation stresses

Two strains of Rhizobium meliloti and one of R. japonicum were grown in broth adjusted to selected water activities (a_w) using KCl, NaCl, LiCl or glycerol. The optimum doubling time for R. meliloti RCR 2011 of 2.5 h (at a_w 0.999) was not affected but the yield at the stationary phase was decreased by a reduction of the a_w to 0.99. Regardless of the solute used, as the a_w was reduced below 0.99 growth rates and yields decreased and lag times were lengthened. The extent to which these responses changed depended on the solute used to lower the a_w. Lag times were affected most when LiCl, NaCl and KCl were used to lower a_w below 0.9866. No growth occurred at a_w 0.969 when NaCl or KCl were used but consistent growth did occur at this a_w when glycerol or LiCl were employed. In contrast with these results, LiCl was more toxic than NaCl for the slow-growing R. japonicum 5. This strain was susceptible to a_w 0.9840 (glycerol).Prior growth of R. meliloti RCR 2011 and 1.5 in media of lowered a_w improved the tolerance of strain RCR 2011 but not of strain 1.5 to desiccation (0% relative humidity).The growth stage of R. meliloti RCR 2011 affected the survival of this strain during storage at different r.h. values. When subjected to drought stress, stationary phase cells survived better than cells collected at three different times during the exponential growth phase.The optimum r.h. value for storage of R. meliloti strain RCR 2011 was within the range 22–43%.Extracellular polysaccharides provided protection against storage at 0% r.h. but their presence was detrimental during storage in semi-dried states.     

New sources of compact spike morphology determined by the genes on chromosome 5A in hexaploid wheat

Little is known about the relationship between compact spike loci in hexaploid wheat species. We studied two new compact spike mutants of common wheat Triticum aestivum L. (2n?=?6x?=?42, genome formula BBAADD). The new compact spike genes, C ⁷³⁹ of MCK 739 and Cp of near-isogenic line Mironovskaya 808 (Vrn1), were mapped using aneuploid stocks and microsatellite markers. The C ⁷³⁹ and Cp loci were distally linked with the microsatellite marker Xbarc319 in the F₂ populations of MCK 739?×?‘Novosibirskaya 67’ and Cp-Mironovskaya 808 (Vrn1)?×?‘Saratovskaya 29’. It was evident that the loci affecting compact spikes in T. aestivum mutants were located on chromosome 5AL distal from Q locus. These loci also affected to semi-dwarfism. We named this locus Cp1 (C ompact p lant 1) for all accessions. Cp1 was allelic to C ¹⁷⁶⁴⁸ gene located on the chromosome 5AL of tetraploid wheat [Triticum durum Desf. (2n?=?4x?=?28, genome formula BBAA)]. These dominant genes on chromosome 5AL will be utilized as new gene resources of compact spike morphology in hexaploid wheat. Relationship between loci Q and Cp1 was also discussed.     

Molecular characterization of two novel alleles of Hordoindoline genes in Hordeum chilense Roem. et Schult.

Grain texture is an important trait in wheat quality, and is related to the presence or absence of puroindolines a and b. In barley, these proteins are synthesised by the Hordoindoline (Hin) genes, orthologs of the Puroindoline (Pin) genes present in bread wheat and Aegilops species. In this study, the variation of Hin genes has been characterized in two representative lines of Hordeum chilense Roem. et Schult., a wild barley species that has been used in the development of a new man-made cereal (tritordeum, ×Tritordeum Ascherson et Graebner). Two novel alleles were detected in this material, one for the Hina-H ^ch 1 gene and another for the Hinb-H ^ch 1 gene. These alleles demonstrated high similarity to the Pin genes of bread wheat, which may explain the soft grain texture of tritordeum. This suggests that the variation present in H. chilense could be utilized in wheat breeding through the use of tritordeum as a bridge species, to extend the range of different textures.     

Development of a Two-Phase Cosolvent Washing-Fungal Biosorption Process for the Remediation of DDT-Contaminated Soil

A bench scale, two-phase soil washing-biosorption process was developed for the remediation of p,p′-DDT-contaminated soil (containing 990 and 7750 mg kg^-1 of p,p′-DDT). Removal of p,p′-DDT from contaminated soil was achieved by washing the soil with low molecular weight primary alcohols (ethanol or 1-propanol). An improved efficiency of p,p′-DDT removal was observed with increasing C-chain length of the cosolvent and by increasing the cosolvent volume fraction. When 40 or 80% 1-propanol were used, greater than 93% of p,p′-DDT was desorbed from the respective soils. p,p′-DDT was partitioned from the cosolvent solutions using biomass of Cladosporium sp. strain AJR³18,501 as the sorptivematrix. When studies were conducted using a cosolvent-recycling regime (with 80% 1-propanol) greater than 95% of p,p′-DDT was removed from Soil A (990 mg kg^-1 p,p′-DDT) and Soil B (7750 mg kg^-1 p,p′-DDT) with the majority of the desorbed organochlorine repartitioning onto the fungal biomass. Less than 2.4 μg mL^-1 p,p′-DDT was detected in the cosolvent wash solution of Soil A after 80 hr: potentially the cosolvent could be further reused to treat other soil. A higher concentration of p,p′-DDT was detected in the cosolvent wash solution of soil B after 120 hr (13.3 μg mL^-1) indicating that the p,p′-DDT sorption sites on the fungal biomass were fully saturated.     

Phenotypic diversity in Cajanus species and identification of promising sources for agronomic traits and seed protein content

A total of 198 accessions representing 18 species of the genus Cajanus, assembled at the ICRISAT genebank, was characterized for 27 morpho-agronomic traits at ICRISAT farm, Patancheru, India. Newman–Keuls test of significance for mean values indicated significant differences among the species for one or more traits under study. Mean diversity for all traits was maximum in C. scarabaeoides (H′ = 0.590 ± 0.010). First three principal components (PCs) captured 84.3 % of total variation among all species. Cluster analysis resulted in three clusters. C. albicans and C. mollis formed Cluster 1; C. cajanifolius, C. crassus and C. platycarpus formed Cluster 2 and C. acutifolius, C. scarabaeoides, C. lineatus and C. sericeus formed Cluster 3. C. platycarpus for extra early flowering (34–40 days); C. scarabaeoides for early flowering (51–118 days); C. albicans for broad pods; C. mollis, C. albicans, C. cinereus for more seeds per pod (>6) and C. crassus, C. cajanifolius, C. mollis, C. platycarpus and C. albicans for high seed protein (>30 %) were found as promising sources. Long duration perennial species such as C. crassus, C. mollis and C. albicans are good sources for forage. Five accessions (ICP 15661, ICP 15664, ICP 15666, ICP 15668 and ICP 15671) of C. platycarpus, two accessions (ICP 15653 and ICP 15658) of C. mollis and one accession each of C. acutifolius (ICP 15611), C. albicans (ICP 15620), C. cajanifolius (ICP 15632), C. crassus (ICP 15768), C. lineatus (ICP 15646), C. scarabaeoides (ICP 15922) and C. sericeus (ICP 15760), found as promising for multiple trait combinations are useful in pigeonpea improvement programs.