Exo-glycosidases Activities in Artemisia sphaerocephala Mucilaginous Achene Germination Process

白沙蒿 (ArtemisiasphaerocephalaKrasch .)是中国西北沙区分布的多年生植物。瘦果遇湿后其粘液层开始膨胀。对其种子萌发不同阶段的种胚提取物中几种可能降解果皮外层粘液物质的外切糖苷酶进行了检测。结果表明 :β 吡喃半乳糖苷酶在干种子中的活性很高 ,但是随着种子的吸涨而逐渐降低 ,在已萌发的种子中无法探测到。α和 β 吡喃阿拉伯糖苷酶、β 吡喃葡萄糖苷酶以及 β 吡喃甘露糖苷酶在种子萌发过程的胚提取物中也显示出了一些活性 ,但是这些活性在种胚外却无法探测到。所有胚提取物中的外切糖苷酶都无法降解果皮粘液物质。所有的证据都表明果皮外层的粘液物质无法在种子萌发的早期被水解。因此果皮粘液物质在干旱沙质条件下的生态功能被限制在吸收水分以及延长胚吸水的时间。

Endo-Glycanhydrolases Activities in Artemisia sphaerocephala (Asteraceae) Mucilaginous Achene Germination Process

对白沙蒿 (ArtemisiasphaerocephahaKrasch .)种子萌发不同阶段的种胚提取物中几种可能降解果皮外层粘液物质的多糖内切酶进行了检测。研究结果表明 :多聚半乳糖醛酸酶在干燥胚中已存在并具较高的活性 ,但其活性随着种子吸涨及萌发而降低。此酶并不释放到种胚外。β 甘露聚糖内切酶随着种子的吸涨而增加并被萌发的种胚释放到种子外。纤维素酶在种子萌发的过程中不表现出活性。提取物中的所有多糖内切酶都无法降解果皮外层的粘液物质。

Time-course transcriptome landscape of achene development in lettuce

Lettuce(Lactuca sativa L.),which belongs to the large Asteraceae(Compositae)family,breeds by sexual reproduction and produces seeds.Actually,lettuce seeds are achenes,which are defined as fruits.However,few studies have described the morphological characteristics of the lettuce achenes,and genes essential for achene development are largely unknown in lettuce.To investigate the gene activity during achene development and determine the possible mechanisms that influence achene development in lettuce,we performed a time-course transcriptome analysis of lettuce achenes.A total of 27,390 expressed genes were detected at the five achene development stages.We investigated the gene expression patterns during achene development and identified the enriched biological processes at the corresponding stages.Kyoto Encyclopedia of Genes and Genomes and Gene Ontology analyses revealed a variety of transcriptomic similarities and differences at different achene development stages.Further,transcription factors and phytohormones were found to play important roles during achene development.Finally,we proposed a working model to illustrate the gene expression modules and possible molecular mechanisms underlying achene development.Our time-course transcriptome data also provide a foundation for future functional studies to reveal the genetic control of achene development in lettuce.

Achene mucilage formation process and extrusion from hydrated pericarp of Mirabilis himalaica

Myxospermy is an important feature of achenes of the alpine plant Mirabilis himalaica,and the achene mucilage increases the germination rate and early seedling growth during exposure to abiotic stresses,which has important functions that allow M.himalaica to survive the extreme climate of the Tibet Plateau.However,achene formation and mucilage extrusion are poorly understood.In the present study,comprehensive analyses were performed on mucilage production during achene development and mucilage release from hydrated achene pericarp in M.himalaica.First,fertilization initiated the development of M.himalaica achenes,during which their color,size and texture were altered dramatically.Second,using a metachromatic staining procedure,cytological events,the establishment of mucilage secretory cells in the inner epicarp layer were observed.The hydration of mature achenes led to the rapid bursting of mucilage secretory cells,which released a hydrophilic gel that surrounded the achenes.Finally,enzymatic digestion indicated that major components of the mucilage were pectins;glucose(41.40%),rhamnose(26.58%),galactose(18.33%),trehalose(12.12%),and mannose(1.57%)were found to be the components of achene by using ion-exchange chromatography.

Boosting Achene Yield and Yield Related Traits of Sunflower Hybrids through Boron Application Strategies

Effects of different boron (B) application methods on growth and yield of sunflower hybrids were checked out at Agronomic Research Farm, University of Agriculture, Faisalabad, Pakistan during spring, 2013. Field experiment was conducted by considering three sunflower hybrids viz., Patron 551, Patron 851 and S-278 along with different methods of B application i.e. no B application, seed treatment @ 0.05% B, soil B application @ 2 kg·ha-1 at sowing, soil B application @ 2 kg·ha-1 at ray floret stage and foliar application of B @ 200 mg·L-1 at ray floret stage. Uttermost plant height (150.78 cm), the number of leaves per plant (22.67) and stem diameter (1.62 cm) were accomplished when boron was soil applied @ 2 kg·ha-1 at sowing. Significantly higher head diameter (18.30 cm), number of achene per head (1266.44), 1000-achene weight (43.17 g) achene yield (2039.33 kg·ha-1), biological yield (9223.11 kg·ha-1) and harvest index (22.10%) were registered when boron was foliar applied @ 200 mg·L-1 at ray floret stage. Among sunflower hybrids, Patron 551 produced significantly higher growth and yield attributes as compared with Patron 851 and S-278 hybrids. This study suggested that the selection of Patron 551 hybrid with practicing boron foliar application @ 200 mg·L-1 at ray floret stage could be helpful in achieving the sunflower crop genetic potential.

Genetic Variation for Achene Traits in Cup Plant (<i>Silphium perfoliatum</i>L.)

Cup plant (Silphium perfoliatum L.) has demonstrated potential for biomass production in studies using transplants in poorly drained cropland not suitable for conventional crops, but little is known about its establishment from seeding. The success rate for stand establishment of perennial plants is usually positively correlated with seed weight. Therefore, objectives of this study were to determine contribution of genetic effects to variation in achene weight, seed weight, achene length, and achene width of cup plant in a population with high biomass potential. Seedlings of 33 half-sib (HS) families were transplanted at Brookings, SD in 1999 and 2010. Achene/seed traits were determined at seed maturity in 2000, 2011 and 2012. Narrow-sense heritability was higher for achene weight and seed weight than that for dimensional achene traits. Within-population genetic variation occurred for achene and seed weight, both of which varied in response to temporal variation in precipitation and temperature. Results of this study indicated the presence of sufficient additive genetic variation for progress from among-family selection for achene weight. Thus, since families with heavy achenes had higher percent seedling emergence and superior seedling vigor compared to families with light achenes, achene weight may be useful for indirect selection for enhanced seed quality in development of new cultivars of cup plant for biomass production on marginal crop land.

Achene Wall Anatomy and Surface Sculpturing of Lactuca L. and Related Genera （Compositae： Lactuceae） with Notes on Their Systematic Significance

The achene wail anatomy and surface sculpturing of 14 species representing Lactuca L. and related genera were Investigated to evaluate inter-and Intrageneric relationships. The achene wall anatomy of the studied species can be divided Into two types： winged and ribbed. The winged type is present in Lactuca L., Pterocypsela Shlh, Clcerblta Wallr., Chaetoserls Shlh and Stenoseris Shlh, and is characterized by protruding wings and costae in transverse section. Winged type achene mesocarps are composed of parenchymatous cells and fiber ceils, and the distinct fibrous strands are confined to the costae or wings of the achenes. The ribbed type is present in Notoseris Shih and Paraprenanthes Chang ex Shih, and Is characterized by only having costae In transverse section. Fiber cells are continuous in the costae and intercostae, in surface sculpturing, the ornamentation and the shape of epidermal cells are different among these genera. The results Indicate that L. altalca and L. serrlola should be conspeclfic, and that L. dollchophylla is probably an Intermediate taxon between Lactuca and Chaetoserls. The results also support the separation of Pterocypseia, Paraprenanthes, Notoseris, Chaetoseris and Stenoserls from Lactuca and Clcerblta as independent entitles. Close affinities between Pterocypsela and Lactuca, Paraprenanthes and Notoserls, and Chaetoserls and Stenoserls are also proposed.

Role of mucilage during achene germination and sprout growth of the endangered Tibetan medicinal herb Mirabilis himalaica (Nyctaginaceae) exposed to abiotic stresses

Aim Mirabilis himalaica(Nyctaginaceae)is an endangered medicinal plant mainly distributed in the plateau region of northern Tibet,China.The outer surface of M.himalaica achenes is covered by a pectinaceous mucilaginous layer upon hydration.However,the role of the achene mucilage is poorly understood.in this study,we inves-tigated the effects of mucilage on achene germination and sprout growth under abiotic stress to explain how M.himalaica survive the alpine environment.Methods We investigated the effect of mucilage on achenes germination by contrast the capacity of water absorption,dehydration and respira-tion of intact achene and the achene with mucilage removal.We performed abiotic stresses experiments including drought stress,salt stress,cold stress and high temperature stress,and quantified the effects of mucilage removal on achene germination rate,root and shoot lengths of seedlings.Important Findings Mucilage is extremely hydrophilic,and the mass of intact achenes can be 9-fold greater than that of demucilaged achenes.The removal of the mucilaginous layer did not significantly change final germination percentages under ideal conditions,but intact achenes(i.e.with muci-lage)took longer to germinate.The mucilage significantly decreased seed respiration rates by acting as a physical barrier that prevented oxygen diffusion.Germination rates,shoot and root growth of intact achenes were higher than those of demucilaged ones during exposures to cold,heat,osmotic and salt stresses.Achene mucilage presumably plays an ecologically important role in the life cycle of M.himalaica by aiding the critical achene germination and early seedling growth in the stressful habitats of the plateau region of northern Tibet.

Comparison of Germination Strategies of Artemisia ordosica with Its Two Congeners from Deserts of China and Israel

Artemisia ordosica Krasch. is a dominant shrub occurring mainly on stable sand dunes in the Gobi Desert of China, in the Mongolian phytogeographic region. Achenes of A. ordosica germinate in light but poorly in dark and light is the limiting factor regulating the achene germination in sand depth. Achenes germinate in spring or autumn with an optimal temperature of 20 ℃. Achene mucilage can absorb large amounts of water and has important ecological function. Salt concentrations and sand moisture may regulate achene germination in sand. A. ordosica, A. sphaerocephala Krasch. and A. monosperma Delile. from different climates have similar responses to light, the underground location of achene, and sand moisture. Percentage of seedling emergence from different levels of sand depth is depends on the specific, temperature and intensity of light penetrating through the sand depths, as well as on sand moisture. The desert sand habitat seems to have had a dominant influence on the evolution of the germination strategies of these 3 Artemisia species.

OILCROP-SUN Model for Nitrogen Management of Diverse Sunflower (<i>Helianthus annus</i>L.) Hybrids Production under Agro-Climatic Conditions of Sargodha, Pakistan

Decision support system for agro-technology transfer (DSSAT), OIL CROP-SUN Model was used to stimulate the phenology, growth, yield of different two sunflower hybrids. i.e. Hysun-33 and S-78 by applying different nitrogen levels. The effect of nitrogen (N) on growth and yield components of different sunflower (Helianthus annuus L.) hybrids were evaluated under agro-climatic conditions of Sargodha, Pakistan during spring 2013. The experiment was laid out in a randomized complete block design with split plot arrangement having three replications, keeping cultivars in the main plots and nitrogen levels (0, 45, 90,135 and 180 kg/ha) in sub plots. OIL CROP-SUN Model showed that the model was able to simulate the growth and yield of sunflower with an average of 10.44 error% between observed and simulate achene yield (AY). The result of simulation indicates that nitrogen rate of 180 kg/ha produced highest achene yield in S-78 hybrid as compared to other treatments and Hysun-33 cultivar.

OILCROP-SUN Model Relevance for Evaluation of Nitrogen Management of Sunflower Hybrids in Sargodha, Punjab

The experiments were conducted to evaluate the performance of crop system (DSSAT) OILCROP-SUN model simulating growth & development and achene yield of sunflower hybrids in response to nitrogen under irrigated conditions in semi arid environment, Sargodha, Punjab. The model was evaluated with observed data collected in trials which were conducted during spring season in 2010 and 2011 in Sargodha, Punjab, Pakistan. Split plot design was used in layout of experiment with three replications. The hybrids (Hysun-33 & S-278) and N levels (0, 75, 150 and 225 kg.ha-1) were allotted in main and sub plots, respectively. The OILCROP-SUN model showed that the model was able to simulate growth and yield of sunflower with an average of 10.44 error% between observed and simulated achene yield (AY). The results of simulation analysis indicated that nitrogen rate of 150 kg.N.ha-1 (N3) produced the highest yield as compared to other treatments. Furthermore, the economic analysis through mean Gini Dominance also showed the dominance of this treatment compared to other treatment combinations. Thus management strategy consisting?of treatment 150 kg.N.ha-1 was the best for high yield of sunflower hybrids.