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25 February 2018, Volume 40 Issue 01
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  • Articles
    Determining bioclimatic space of Himalayan alder for agroforestry systems in Nepal
    Santosh Kumar Rana, Hum Kala Rana, Krishna Kumar Shrestha, Suresh Sujakhu, Sailesh Ranjitkar
    2018, 40(01):  1-18.  doi:10.1016/j.pld.2017.11.002
    Abstract ( 52 )   HTML ( )   PDF (12657KB) ( 17 )   Save
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    Himalayan alder species are proven to be very useful in traditional as well as contemporary agroforestry practice. These nitrogen-fixing trees are also useful in the land restoration. Therefore, understanding the distribution of Himalayan alder and the potential zone for plantation is meaningful in the agroforestry sector. Suitable climatic zones of Alnus spp. were modelled in MaxEnt software using a subset of least correlated bioclimatic variables for current conditions (1950-2000), topographic variables (DEM derived) and Landuse Landcover (LULC) data. We generated several models and selected the best model against random models using ANOVA and t-test. The environmental variables that best explained the current distribution of the species were identified and used to project into the future. For future projections, ensemble scenarios of climate change projection derived from the results of 19 Earth System Models (ESM) were used. Our model revealed that the most favorable conditions for Alnus nepalensis are in central Nepal in the moist north-west facing slope, whereas for Alnus nitida they are in western Nepal. The major climatic factor that contributes to Alnus species distribution in Nepal appears to be precipitation during the warmest quarter for A. nepalensis and precipitation during the driest quarter for A. nitida. Future projections revealed changes in the probability distribution of these species, as well as where they need conservation and where they can be planted. Also, our model predicts that the distribution of Alnus spp. in hilly regions will remain unchanged, and therefore may represent sites that can be used to revitalize traditional agroforestry systems and extract source material for land restoration.
    Physiological and biochemical analysis of mechanisms underlying cadmium tolerance and accumulation in turnip
    Xiong Li, Xiaoming Zhang, Yuansheng Wu, Boqun Li, Yongping Yang
    2018, 40(01):  19-27.  doi:10.1016/j.pld.2017.12.005
    Abstract ( 33 )   HTML ( )   PDF (6300KB) ( 9 )   Save
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    The capacity of plants to accumulate cadmium (Cd) is significant for phytoremediation of Cd-polluted soils. Turnips cultivated in China include species featuring high Cd accumulation and some of these plants act as Cd hyperaccumulator landraces. These plants can accumulate over 100 mg Cd kg-1 dry weight in leaves without injury. Hence, studies that explore mechanisms underlying Cd detoxification and transport in turnip plants are essential. In the present study, we compared physiological and biochemical changes in turnip leaves treated with two Cd concentrations to controls. We discovered that Cd stress significantly increased the enzymatic activities or compound contents in the antioxidant system, including members of the glutathione-ascorbic acid cycle, whereas oxidation of reactive oxygen species (ROS) remained stable. Cd treatments also increased the contents of phytochelatins as well as a number of amino acids. Based on these results, we conclude that turnips initiate a series of response processes to manage Cd treatment. First, the antioxidant system maintaining ROS homeostasis and osmotic adjustment is excited to maintain stability of cell osmotic potential. Cd is chelated into its stable form to reduce its toxicity. Cd is possibly transported to vacuoles or non-protoplasts for isolation. Amino acid synthesis may directly and indirectly play an important role in these processes. This study partly revealed physiological and biochemical mechanisms underlying turnip response to Cd stress and provides information on artificially increasing or decreasing Cd accumulation in turnips and other plants.
    Light induces petal color change in Quisqualis indica (Combretaceae)
    Juan Yan, Menglin Wang, Ling Zhang
    2018, 40(01):  28-34.  doi:10.1016/j.pld.2017.11.004
    Abstract ( 46 )   HTML ( )   PDF (3408KB) ( 10 )   Save
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    Petal color change, a common phenomenon in angiosperms, is induced by various environmental and endogenous factors. Interestingly, this phenomenon is important for attracting pollinators and further reproductive success. Quisqualis indica L. (Combretaceae) is a tropical Asian climber that undergoes sequential petal color change from white to pink to red. This color changing process is thought to be a good strategy to attract more pollinators. However, the underlying physiological and biochemical mechanisms driving this petal color change phenomenon is still underexplored. In this context, we investigated whether changes in pH, pollination, light, temperature or ethylene mediate petal color change. We found that the detected changes in petal pH were not significant enough to induce color alterations. Additionally, pollination and temperatures of 20-30℃ did not alter the rate of petal color change; however, flowers did not open when exposed to constant temperatures at 15℃ or 35℃. Moreover, the application of ethylene inhibitor, i.e., silver thiosulphate, did not prevent color change. It is worth mentioning here that in our study we found light as a strong factor influencing the whole process of petal color change, as petals remained white under dark conditions. Altogether, the present study suggests that petal color change in Q. indica is induced by light and not by changes in petal pH, pollination, ethylene, or temperature, while extremely low or high temperatures affect flower anthesis. In summary, our findings represent the probable mechanism underlying the phenomenon of petal color change, which is important for understanding flower color evolution.
    Morphological study of floral nectaries in Euonymus and the probable origin of the echinate fruit surface
    Chiyuan Yao, Yunjuan Zuo, Cheng Du, Jinshuang Ma
    2018, 40(01):  35-40.  doi:10.1016/j.pld.2017.12.004
    Abstract ( 53 )   HTML ( )   PDF (7148KB) ( 13 )   Save
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    A conspicuous nectary disk is common but has a distinguishing morphology in the cosmopolitan genus Euonymus. Our study focuses on the morphology of floral nectaries in 21 representatives of Euonymus and Glyptopetalum. Two main types of nectaries were documented:a mix of inter-and extrastaminal nectaries existed between the corolla and the stigma, while the intrastaminal nectaries were distributed between the stigma and the stamen bases. The main route of nectar release in Euonymus is via modified stomata, and different nectarostomata locations were observed:in depressions, slightly raised above the epidermal surface or at the same level as the epidermis. Floral nectaries in E. sect. Echinococcus species developed into the protrusions on the fruit surface at the later stage. The development of nectaries not only explained the mystery of the origin of the echinate fruit surface, but also showed that differences in fruit surface might be inappropriate for use in infrageneric classification. These discoveries inform morphological observations of floral nectaries in Euonymus.
    Development and characterization of 43 microsatellite markers for the critically endangered primrose Primula reinii using MiSeq sequencing
    Masaya Yamamoto, Yoshihiro Handa, Hiroki Aihara, Hiroaki Setoguchi
    2018, 40(01):  41-44.  doi:10.1016/j.pld.2017.09.003
    Abstract ( 29 )   HTML ( )   PDF (1045KB) ( 9 )   Save
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    Primula reinii (Primulaceae), a perennial herb belonging to the Primula section Reinii, occurs on wet, shaded rocky cliffs in the mountains of Japan. This threatened species comprises four varieties; these plants are very localized and rare in the wild. In this study, 43 microsatellite markers were developed using MiSeq sequencing to facilitate conservation genetics of these critically endangered primroses. We developed novel microsatellite markers for three varieties of P. reinii, and tested its polymorphism and genetic diversity using natural populations. These novel markers displayed relatively high polymorphism; the number of alleles and expected heterozygosities ranged from 2 to 6 (mean=3.2) and 0.13 to 0.82 (mean=0.45), respectively. All loci were in HardyeWeinberg equilibrium. These microsatellite markers will be powerful tools to assess P. reinii genetic diversity and develop effective conservation and management strategies.