2018

Permanent URI for this collectionhttps://hdl.handle.net/1807/81038

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Overlooked Diversity in Exotic Taraxacum in British Columbia, Canada.
(Canadian Science Publishing, 2018-12-29) Björk, Curtis
In almost all North American literature, including in British Columbia, weedy Taraxacum species have been named as T. officinale and T. erythrospermum (or T. laevigatum). This coarse taxonomic approach ignores great diversity in morphology, ecology and geographical distributions among the exotic established species. Taxonomic refinement would facilitate floristics and ecological studies when exotic Taraxacum species are involved, and the taxonomy of native Taraxacum must first determine which are and which are not native species, which in turn requires knowledge of sectional identity of any specimen. Exotic Taraxacum specimens were identified to species and taxonomic sections using refined species and sectional concepts that align with taxonomic standards used in the native ranges of the species in Europe. Seven exotic sections and one informally named group are found to be present in British Columbia (Borea, Boreigena, Celtica, Erythrosperma, Hamata, Naevosa, Taraxacum, and the T. fulvicarpum group). The number of exotic Taraxacum species known to occur in British Columbia to date exceeds 100. A key to the exotic sections of British Columbia Taraxacum is presented and the sections are characterized. Species known to date are listed by their sectional placement. Notes are also presented on distinguishing native from exotic Taraxacum in British Columbia.
Seed banks of sub-tropical grassland patches within an urban matrix in South Africa: Reflecting the past and foretelling the future
(Canadian Science Publishing, 2018-12-19) Sershen; Drury, Charmaine Crystal; Carbutt, Clinton; Ramdhani, Syd
Abstract: Urban grasslands often exist as fragmented patches with varying threat levels. These patches are generally inappropriately managed due to limited data on their responses to disturbance and seed bank regenerative potential. This study compared seed banks between non-naturally disturbed and undisturbed patches of South African sub-tropical grasslands in an urban environment. Standing vegetation was characterised via year-round quadrat and monthly transect sampling. The seed banks were sampled after the two main dispersal periods and assessed for species composition and density. The seed bank species (24) represented a subset (9%) of the standing vegetation, with forbs being the most speciose life form and grasses the most abundant. Disturbance had a moderate impact on seed bank density but significantly affected species composition and ordering. Clustering and ordination analyses separated seed banks based on disturbance history. However, seed banks in disturbed patches maintained the general character of the grassland type. Diagnostic, rare and threatened taxa were absent from seed banks, irrespective of disturbance history. Consequently, restoration will possibly require seed enrichment and species reintroduction rather than exploitation of natural seed banks. Identifying disturbance-sensitive species through seed bank surveys can inform grassland conservation and restoration strategies.
Effects of bisphenol-A and folic acid on growth, reproductive development, and DNA methylation in snapdragons (Antirrhinum majus)
(Canadian Science Publishing, 2018-10-09) Heo, Kayoung; Gibson, Glenys; Evans, Rodger C.
Bisphenol-A (BPA), used in the production of polycarbonate plastics, exerts complex effects on organismal development and on their epigenomes as a methylation disruptor. BPA is of concern due to its ubiquity in the environment. In contrast, folic acid can promote plant growth and has been shown to correct the methyl disrupting effects of BPA in mice. We investigated the effects of prolonged exposure to BPA and folic acid on plant height, dry weight, and DNA methylation of floral tissues of Antirrhinum majus (Snapdragons) from seedling to floral senescence. At low and medium concentrations (5 and 25 mg/L), BPA had a growth promoting effect early in development and appeared to accelerate floral development compared to controls. At senescence, plants treated with low and medium-dose BPA had decreased dry weight compared to controls. Folic acid promoted growth early through mid-vegetative development and also promoted early flowering. In general, acceleration of floral development associated with low dose BPA and folic acid correlated with higher DNA methylation percentages. These data suggest that prolonged exposure to BPA influence plant growth and floral development, and cause epigenetic modifications that may potentially be alleviated through application of folic acid thus suggesting significance for environmental protection.
Relationship of alternate bearing and apical bud development in cranberry (Vaccinium macrocarpon Ait.)
(Canadian Science Publishing, 2018-09-29) Bolivar-Medina, Jenny L; Zalapa, Juan; Atucha, Amaya; Patterson, Sara E
Similar to other woody crops, cranberry (Vaccinium macrocarpon Ait.) exhibits alternate bearing or a tendency to produce heavier yields one year followed by lighter yields the next year. Unfortunately, despite the occurrence in many fruit crops, this trait is not well understood. The variable differentiation of floral initials in cranberry uprights is a distinguishing characteristic associated with alternate bearing. This study evaluates bud morphology and the presence of floral initials through characterization of longitudinal sections of apical buds from vegetative and fruiting uprights of alternate and non-alternate bearing genotypes. Our results reveal that differentiation of floral initials in fruiting uprights only occurs in non alternate bearing genotypes and after initiation in vegetative uprights. In addition, a strong positive correlation was found between the increase of bud width and the presence of floral initials. Last, uprights from the alternate bearing genotype exhibited significantly faster growth rates of the reproductive buds as compared to the vegetative buds. In summary, our study shows marked differences in timing and growth rates of floral initials between uprights of the two genotypes suggesting possible correlation with resource allocation during the growth season and thus could contribute to cultivar selection and management practices.
Habitat filtering influences plant-pollinator interactions in prairie ecosystems
(Canadian Science Publishing, 2018-12-15) Bizecki Robson, Diana; Hamel, Cary; Neufeld, Rebekah; Bleho, Barbara I.
The xeric hypothesis is that bees are more abundant pollinators in dry, temperate biomes than anthophilous flies, and the habitat filtering hypothesis is that differences in the proportions will impact plant community composition because different pollinators favour different floral traits. However, few studies have examined the predictive value of these hypotheses. In particular, differences in plant-pollinator compositions within biomes, such as the Prairie Ecozone, have not been compared. We documented plant-pollinator interactions and plant abundance in three Canadian prairie types. Flower visits in moist tall grass prairie were mainly by flies in the Syrphidae, while visits in the drier fescue and mixed grass prairie were mainly by long-tongued bees in the Apidae. Short-tongued bee visits were not significantly different between the prairie types. Insect visits to tubular, zygomorphic, violet/blue- and white-flowered plants were higher in drier fescue and mixed grass prairie than in moister tall grass prairie. Further, proportions of plants with these features were lower in the tall grass prairie. Thus differences in the proportion of flies and long-tongued bees, likely affected by habitat conditions including moisture levels, appear to be influencing the types of plants that dominate each prairie type providing some support for these hypotheses.
Syconium development in Ficus petiolaris (Ficus, sect. Americanae, Moraceae) and their relationship with pollinator and parasitic wasps.
(Canadian Science Publishing, 2018-12-08) Piedra-Malagón, Eva María; Hernández-Ramos, Balbina; Mirón-Monterrosas, Ana; Cornejo-Tenorio, Guadalupe; Navarrete-Segueda, Armando; Ibarra-Manríquez, Guillermo
For the first time in a Neotropical Ficus species (F. petiolaris), the external and internal structural changes in its syconia are described together with the development of its fig wasps. Ficus petiolaris is endemic to Mexico and represents the northernmost limit of the geographical distribution of the genus in America. Considering the large variation in syconium morphology, we evaluate whether there are differences between syconium development in F. petiolaris and that described for Paleotropical species. We recorded the development of 428 syconia in two individuals, weekly for a period of five months, from initiation to maturity, as well as that of their associated insects. The time required for completion of syconia development ranged from 91 to 126 days. The external morphology of the syconia (color, ostiole size and thickness of syconium wall) enabled phase recognition. Male and female of pollinators (Pegoscapus sp.) and parasitic wasps (Idarnes sp.) were registered. High seed germination values (50-90 %) tested indirectly the positive role of pollinators. Our results are similar to those reported in Paleotropical Ficus species and should contribute to our understanding about syconium development as well as to the relationships that they maintain with their Agaonidae wasps.
Conocarpus lancifolius Engl. (Combretaceae) photosynthetic apparatus suffers damage in heavy metal contaminated soil
(Canadian Science Publishing, 2018-12-08) Redha, Amina; Al-Hasan, Redha; Jose, Jacquilion; Saju, Divya; Afzal, Mohammad
Conocarpus lancifolius Engl. (Combretaceae), a heat tolerant plant, could be used for phytoremediation of polluted soil. We aimed to analyze the physiological changes in C. lancifolius exposed to single and mixed heavy metals (HMs), cadmium (Cd2+), nickel (Ni2+), and lead (Pb2+). Under controlled growth conditions, some groups of plants were exposed to a single HM at concentrations of 25 or 50 µM and other groups were exposed to 25 µM HM mixtures, for 30 days. Photosynthetic parameters such as electron transport rate, photosynthetic rate, chlorophyll fluorescence, chlorophyll content index, and photosynthetic pigments were measured. The chloroplast morphology was studied by transmission electron microscopy (TEM). In plants exposed to HM 25 µM, the photosynthetic parameters were unaffected, whereas at HM 50 µM, all parameters significantly decreased until 20 days of exposure followed by an increase until 30 days, indicating a slow adaptability of plants under HM stress. Compared to single HMs, mixed HMs were more toxic at the same concentration. All parameters indicated damage to the photosynthetic apparatus due to stress from mixed HMs at 25 µM and single HMs at 50 µM. TEM analyses showed a dispersion of grana in the chloroplast of the affected C. lancifolius plants.
A novel ageing-repair bacterium, Pseudomonas geniculata isolated from rescuegrass (Bromus cartharticus Vahl) promotes germination and seedling growth of the aged seeds
(Canadian Science Publishing, 2018-11-16) Liu, Xv; Chen, Zhao; Gao, Yani; Liu, Qian; Zhou, Wennan; Zhao, Tian; Jiang, Wenbo; Cui, Xuewen; Cui, Jian; Wang, Quanzhen
Plant growth-promoting rhizobacteria (PGPR) are documented to relieve various biotic and abiotic stresses, but little information is available regarding their influence on germination and seedling growth of aged seeds. We isolated the promising PGPR from rescuegrass (Bromus cartharticus Vahl) roots and investigated the effect of PGPR biopriming combined with another seed priming treatment on aged rescuegrass seeds using an orthogonal matrix design with four factors. A potential ageing-repair bacterium, BCR5 (Pseudomonas geniculata), was selected from the screening trials and was identified. The reintroduction of strain BCR5 into the aged seeds pre-primed with different approaches had positive effects on the germination and seedling growth. Results indicated that the bacterial cell density was the most effective factor for seed germination and vigour. Four factors were optimized for this study including artificial ageing duration of 54.21 h, bacterial cell density of 527.50 Ă 106 CFU/mL, H2O2 priming for 14.50 h after the analyses of range, variance and binary quadratic regressions. Furthermore, the treatment also affected the malondialdehyde content and superoxide dismutase and peroxidase activities. The PGPR bio-priming with another seed priming approach might be exploited as a promising technique to repair aged seeds. Moreover, it was unexpectedly found that the appropriate artificial ageing treatment could release seed dormancy.
Overcoming root dormancy and identifying the storage behaviour of Lilium polyphyllum seeds
(Canadian Science Publishing, 2018-11-16) Dhyani, Anurag; Baskin, Carol C.; Nautiyal, Bhagwati Prasad; Nautiyal, Mohan Chandra
Lilium polyphyllum is a critically endangered medicinal herb of Himalaya. Seeds have epicotyl morphophysiological dormancy, and in the field a minimum of 34 weeks is required for root emergence. To date, treatments to decrease the time for root protrusion and seed storage behaviour have not been determined. We evaluated the effects of plant growth regulators and nitrogenous compounds and seed scarification on root emergence and determined the storage behaviour of seeds. Root emergence at 20°C was significantly increased by 100 ppm IBA, KNO3 and thiourea and by application of NaOCl solution for 30 min. Mean germination time was decreased significantly by 50 ppm GA3 (28 days) compared to 100 ppm GA3 (36 days). After 12 months of dry storage, viability of seeds (TTC method) at room temperature (10-35°C), 0-4°C and -20±1°C was 95%, 100% and 100%, respectively; thus, seeds have orthodox storage behaviour. Our recommendation for seedling production is to store seeds at room temperature until they can be sown under warm wet conditions. Roots emerge after about 8 weeks, and then seeds should be given a 2-week cold moist treatment to break shoot dormancy. After 2 weeks of cold, transfer seeds to warm (20°C) spring temperatures to promote growth.
Physical defenses and herbivory vary more within plants than among plants in the tropical understory shrub Piper polytrichum
(Canadian Science Publishing, 2018-11-07) Wetzel, William C; Meek, Mariah
There is a growing appreciation that much of the trait variation within plant species is represented within individuals, for example, occurring among leaves within a plant. Subindividual variation is predicted to have key ecological consequences, but empirical understanding of how subindividual variation relates to species interactions, such as herbivory, is limited. We measured two physical defenses and herbivore damage on multiple leaves within individual plants of Piper polytrichum (Piperaceae), a tropical understory shrub. We partitioned variance among- and within-plants and quantified patterns of trait and damage variation vis-Ă -vis leaf size and architectural position. We found that variance was considerably higher within plants than among plants for toughness (97%) and trichome density (57%), and that herbivore damage also varied most within plants (74%). Surprisingly, leaf position and size explained only small amounts of variance in traits (2.5â 16.5%) and herbivory (â ¤ 4%), indicating subindividual variability had low spatial predictability. The data suggest individual P. polytrichum plants represent heterogeneous and spatially unpredictable landscapes of physical traits and that interactions with herbivores are similarly variable. Our results are consistent with the hypothesis that subindividual variability defends plants against herbivores by increasing the difficulty of foraging for high-quality tissue.
Adaptive drought tolerance during germination of Salsola drummondii seeds from saline and non-saline habitats of the Arid Arabian Deserts
(Canadian Science Publishing, 2018-11-16) Elnaggar, Attiat; El-Keblawy, Ali; Mosa, Kareem; Navarro, Teresa
The effects of temperature, light, salinity, and drought on germination of halophytes have been extensively studied. However, few studies have focused on the germination of plants that grow well in both saline and non-saline habitats (i.e., habitat-indifferent halophytes). Here, we assess the impacts of population origin, temperature, and light on drought tolerance, as simulated by polyethylene glycol (PEG), during germination of Salsola drummondii, a habitat-indifferent halophyte from the arid Arabian deserts. Seeds were collected from both saline and non-saline habitats and germinated at six PEG levels at three temperatures and two light regimes. An increase in PEG concentration resulted in a significant reduction in seed germination, especially at higher temperatures. Seeds from the non-saline habitat attained significantly greater germination efficiency at PEG levels up to -1.2 MPa, but there was no difference in germination of seeds between the two habitats at -1.5 MPa PEG concentrations. Saline habitat seeds germinated significantly faster at higher PEG levels. Germination was significantly higher in dark than in light at -1.5 MPa at lower temperatures, but the opposite was true at higher temperatures. Seeds from saline habitats had higher dormancy and faster germination at higher concentrations of PEG due to adaptation to low osmotic potentials.
Structure of floral nectaries and comparison of reproductive and vestigial organs in the staminate and pistillate flowers of dioecious Silene latifolia (Caryophyllaceae)
(Canadian Science Publishing, 2018-08-23) Anderson, Jay F.; Duddu, Hema S.N.; Shirtliffe, Steven; Davis, Arthur R.
Silene latifolia Poiret of Eurasia has established in North America, prompting this structural study of its mature unisexual buds and flowers. Floral nectaries, anther and stigma changes, and vestigial reproductive structures were studied using light and scanning electron microscopy. In staminate flowers, anthers dehisced before anthesis and > 90% of their pollen was liberated within 36 h. Accumulated in the tubular calyx, nectar descended an anthophore from the stomatal-bearing nectary at the stamen bases. Nectary tissue surrounded the pistillode, a central filamentous organ lacking ovules but tipped by hairs resembling stigmatic papillae. In pistillate flowers, nectar flowed into an inflated calyx. The annular nectary had 10 regularly-spaced, stomatal-lined craters and was continuous with the adaxial surfaces of the infertile antisepalous and epipetalous staminodes. Key elements of entomophilous pollination leading to successful sexual reproduction of this invasive species include secondary nectar presentation from disparate floral nectaries which, for pistillate flowers, also incorporate the staminodes; rapid pollen release from anthers; and elongation of papillae by tip growth that enhances each stigmaâ s receptive surface. Context is also provided for future studies of floral nectary development in this model dioecious species.
Anthropogenic and soil environmental drivers of arbuscular mycorrhizal community composition differ between grassland ecosystems
(Canadian Science Publishing, 2018-09-25) Tipton, Alice G.; Middleton, Elizabeth L; Spollen, William G; Galen, Candace
Arbuscular mycorrhizal fungal (AMF)- plant interactions are sensitive to myriad underlying factors including soil chemistry and land use disturbances. Here we address how two south-central USA grassland ecosystems (Ozark glades vs. tallgrass prairies) have been impacted by legacy effects from land use disturbances (e.g., fire suppression in glades and tillage, fertilizer, row cropping, and grazing in prairies) and geological substrate (acidic versus calcareous bedrock). We surveyed AMF on roots of two native generalist host species (Ruellia humilis and Schizachyrium scoparium) as well as plants selected randomly from the plant community. Glades on calcareous bedrock had a higher pH than those on acidic bedrock, and AMF communities on all three root sample types varied between acidic and calcareous bedrock locations. In prairies, both bedrock types had a similar soil pH, and AMF communities on all three root sample types varied across remnant and disturbed prairies. Shifts in AMF composition across land use history included shifts in dominant AMF genera, and some unique rare AMF taxa were restricted to only calcareous glades or remnant prairies. Our findings suggest that reseeding prairie plant communities on cultivated lands does not restore AMF communities. Restoration needs to address the soil environment and community.
Floral organogenesis of Prunus laurocerasus and P. serotina and its significance for the systematics of the genus and androecium diversity in Rosaceae
(Canadian Science Publishing, 2018-10-27) Wang, Xi; Gong, Jing-zhi; Li, Qiu-jie; Wang, Jun-ru; Ma, Yue-ping; Zhang, Xiao-hui; Chang, Zhao-yang; Wen, Jun; Zhao, Liang
Phylogenetic studies have shown that most clades in Prunus are well-supported by the flower structure, but most taxa in the racemose group have not yet been re-evaluated and could contribute to the understanding of the systematic relationships of the subgenera. We examined the inflorescence and flower development in Prunus laurocerasus (subg. Laurocerasus) and P. serotina (subg. Padus I) using scanning electron microscopy. Our results indicate that they share several floral development characters but differ in the following aspects: (1) all flowers are fully developed and each flower is enclosed by a bract and two bracteoles, which later stop development (vs. the terminal flower degenerates and only a single bract subtends each flower), (2) the style protrudes from the floral bud (vs. the style is crooked and below the anthers), (3) the outer integument initiates close to the inner one (vs. in the middle of the ovule), and (4) an obturator appears after initiation of the two integuments (vs. simultaneously with the inner integument). Although our results are preliminary, differences in floral developmental characters support the different origins of Prunus subgenera Laurocerasus and Padus as based on molecular phylogenetic studies.
Molecular evidence for natural hybridization between Ligularia nelumbifolia and Cremanthodium stenoglossum (Asteraceae, Senecioneae)
(Canadian Science Publishing, 2018-10-27) Ning, Huai; Pan, Yue-Zhi; Gong, Xun
Natural hybridization occurred frequently in the sunflower family. To date, however, no study on natural hybridization involving in Ligularia and Cremanthodium has been reported. Here, we presented the molecular evidence for natural hybridization between Ligularia nelumbifolia and Cremanthodium stenoglossum. Four nuclear DNA regions were sequenced to test the natural hybridization hypothesis and three chloroplast DNA regions were sequenced to elucidate the direction of hybridization. Analyses of the investigated DNA data suggested that all the putative hybrid individuals were derived from hybridization between L. nelumbifolia and C. stenoglossum and the bidirectional hybridization occurred. Moreover, sympatric L. tsangchanensis and L. virgaurea were not apparently involved in the hybridization. Although NewHybrids analysis showed that all the putative hybrid individuals were F1 class, a low frequency of backcrossing to C. stenoglossum might exist in the hybrid swarm. In such case, hybrids might serve as a bridge facilitating gene flow between L. nelumbifolia and C. stenoglossum, and hybrid speciation is unlikely to happen for these hybrid individuals without asexual reproduction. Given the poorly resolved phylogenetic relationship between Ligularia and Cremanthodium, the occurrence of natural hybridization between L. nelumbifolia and C. stenoglossum might provide new insights into the recircumscription and redelimitation of these two genera.
Differences in foliar endophyte communities of red alder (Alnus rubra) exposed to varying air pollutant levels
(Canadian Science Publishing, 2018-07-10) Wolfe, Emily R; Kautz, Stefanie; Singleton, Sebastian L; Ballhorn, Daniel J
In the Pacific Northwest, Alnus rubra (red alder) is a common deciduous tree species especially prevalent in riparian corridors and disturbed sites, including metropolitan areas undergoing land use changes and development. Importantly, red alder is also considered a bioindicator for ozone pollution, and, like all plants, harbors a diverse endophyte community that may interact with aerial pollutants. In this study, we surveyed foliar fungal endophyte communities (microfungi) in red alder leaves from the metropolitan area of Portland, Oregon, USA using culture-based techniques, and found that communities differed significantly by site. Our results suggest that fungal endophyte community composition in red alder leaves may be influenced in part by local air pollution sources, likely in conjunction with other site characteristics. As urban areas expand, more studies should focus on how the urban environment affects plant-microbe community ecology and endophyte-host interactions, as well as if there are long-term consequences for other ecosystem processes such as leaf litter decomposition.
Physiological and growth responses of potato cultivars to heat stress
(Canadian Science Publishing, 2018-08-13) Tang, Ruimin; Niu, Suyan; Zhang, Guodong; Chen, Guanshui; Haroon, Muhammad; Yang, Qing; Rajora, Om P.; Li, Xiu-Qing
Climate warming is subjecting plants to heat stress, which can affect their physiological processes impacting their growth, development and productivity. Potato (Solanum tuberosum) is a staple food worldwide but potato crops are very sensitive to heat stress. We have studied the effects of heat stress on SPAD-measured leaf chlorophyll content, plant growth and tuber yield of 55 commercial potato cultivars in clonal tests under heat-stress (HS; 35 째C-day, 28 째C-night) and control non-stress (CK; 22 째C-day, 18 째C-night) conditions. The potato cultivars varied in their response to heat stress. Overall, heat stress reduced leaf size, increased the leaf chlorophyll SPAD values by up to 65% and plant height by 64%, but severely reduced the largest tuber weight by 93%. The HS-to-CK SPAD ratios were positively correlated with HS-to-CK plant height ratio, largest tuber weight under heat-stress, and the HS-to-CK largest tuber weight ratio. Potato cultivars displayed a correlated response to heat stress for their leaf chlorophyll content, plant height and tuber weight. We have identified the most heat-tolerant and heat-susceptible cultivars for these traits. Under heat-stress conditions, potato cultivars tend to have less reduction in tuber weight if their plants have higher increase in leaf chlorophyll content and plant height.
Seasonal changes in the occurrence of embolisms among broadleaved trees in a temperate region
(Canadian Science Publishing, 2018-10-16) Umebayashi, Toshihiro; Fukuda, Kenji
Sap freeze–thaw events are a main determinant of the distribution of broad-leaved woody plants in cool regions but the effect in other climates remains unknown. We used cryoscanning electron microscopy to examine the differences in plant growth patterns based on seasonal variation in xylem water distribution in four broad-leaved species (one ring-porous and three diffuse-porous species) in a temperate region of Japan. Leaf fall was detected in November for the ring-porous species Maackia amurensis Rupr. et Maxim., although embolisms were detected in large earlywood vessels in January of the following year. The percentage of embolisms in latewood vessels varied significantly between years. By contrast, xylem embolisms in diffuse-porous species (deciduous and evergreen) were barely detectable during winter. In one evergreen species, embolisms and refilling were detected in some vessels during the growing season. Based on the variation in the number of freeze–thaw events among years in Asian monsoon forests, we infer that M. amurensis obtained no benefit from extending leaf phenology because of the occurrence of vessel embolisms in winter. On the other hand, the leaf phenologies of deciduous and evergreen diffuse-porous species were less constrained by winter embolisms. Maackia amurensis persists in cool temperate regions by limiting the photosynthetic period.
Decreased number of locules and pericarp cell layers underlie smaller and ovoid fruit in tomato smaller fruit (sf) mutant
(Canadian Science Publishing, 2018-09-01) Zhang, Yan; Li, Yushun; Zhang, Jie; Muhammad, Tayeb; Liang, Yan
Fruit size and shape are the prime criteria for domestication and improvement of tomato. The varying sizes and shapes of tomato fruits further signify their importance as agronomic traits. Here, we characterized a tomato mutant, smaller fruit (sf), which bears relatively small and ovoid fruits compared with large and flat fruits of wild-type (WT). Phenotypic measurements and histological analyses revealed that fruit diameter but not fruit length of sf mutant decreased compared with that of WT. This phenotypic change was attributed to significant decreases in locule number and pericarp cell layers in transverse direction, which resulted in the transition of fruit shape from flat in WT to ovoid in sf. Comparison of transcriptomes of ovaries between sf and WT by RNA-Seq identified 2,596 differentially expressed genes, in which 1,737 genes significantly up-regulated and 859 genes dramatically down-regulated in the sf ovary. Further analyses confirmed that some genes, such as CRCa, CNRs, CYCs, WUS, SUNs, OFRs, CDKs, participate in regulation of fruit size and shape of sf mutant. Thus, our study adds a new genetic resource regarding fruit size and shape of tomato, and provides a valuable basis for dissecting molecular regulation of small and ovoid fruit of sf mutant.
Inter- and intra-varietal variation in aerobic methane emissions from environmentally-stressed pea plants
(Canadian Science Publishing, 2018-08-23) Abdulmajeed, Awatif; Abo Gamar, Mohammad; Qaderi, Mirwais M.
Environmental stress factors can influence methane (CH4) emissions from plants. There are few studies on the interactive effects of stress factors on plant aerobic CH4, but none on the comparative evaluation of CH4 emissions between/among plant varieties. We examined the effects of temperature, UVB radiation and watering regime on CH4 from 10 pea varieties first, and then selected two varieties with highest (237J Sundance; var. 1) and lowest (422 Ho Lan Dow; var. 2) emissions for further studies. Plants were grown in controlled-environment growth chambers under two temperatures (22/18oC and 28/24oC, 16 h light/8 h dark), two UVB levels (0 and 5 kJ mâ 2 dâ 1) and two watering regimes (well-watered and water-stressed) for 14 days, after one week of growth under 22/18oC. Higher temperatures and water stress increased CH4 emissions, and increased emission was associated with stress. Pea varieties varied in growth and CH4 emissions; var. 1 was more stressed and had higher emission than var. 2. In the stressed variety, the water-stressed plants grown under higher temperatures at UVB5 had highest CH4 emission, whereas the well-watered plants grown under lower temperatures at UVB5 had lowest emission. We conclude that climatic stress conditions increase CH4 emissions, which vary with plant varieties.

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