Acta Physiologiae Plantarum

Jiang, Huanhuan; Xiao, Yao; Zhu, Suwen

doi: 10.1007/s11738-018-2738-0pmid: N/A

SIMILAR TO RCD ONE (SRO) is a small plant-specific gene family, which play essential roles in plant growth and development as well as in abiotic stresses. However, the function of SROs in maize is still unknown. In our study, six putative SRO genes were isolated from the maize genome. A systematic analysis was performed to characterize the ZmSRO gene family. The ZmSRO gene family was divided into two groups according to the motif and intron/exon analysis. Phylogenetic analysis of them with other plants showed that the clades of SROs along with the divergence of monocot and dicot and ZmSROs were more closely with OsSROs. Many abiotic stress response and hormone-induced cis-regulatory elements were identified from the promoter region of ZmSROs. Furthermore, RNA-seq analysis indicated that SRO genes were widely expressed in different tissues and development stages in maize, and the expression divergence was also obviously observed. Analyses of expression in response to PEG6000 and NaCl treatment, in addition to exogenous application of ABA and GA hormones showed that the majority of the members display stress-induced expression patterns. Taken together, our results provide valuable reference for further functional analysis of the SRO gene family in maize, especially in abiotic stress responses.

Jiao, Jie; Bai, Zhenqing; Huang, Wenli; Xia, Pengguo; Liu, Feng; Ma, Cunde; Liang, Zongsuo

doi: 10.1007/s11738-018-2756-ypmid: N/A

Polygonati rhizoma (PR) is an important and widely used product in Chinese traditional medicine and edible goods. The time-consuming nature of breaking dormancy in both rhizomes and seeds means that improving variety selection is limited to collection, identification, and selection of germplasms. In this study, we used two DNA-based molecular marker techniques—inter simple sequence repeat (ISSR) and start codon targeted (SCoT)—to assess the genetic diversity and population structure among PR source plants collected from 47 different regions and belonging to 12 populations (P1–P12). For molecular markers analysis, 15 ISSR and 10 SCoT markers were tested. Total number of 159 fragments (150–4000 bp) were amplified based on ISSR analysis with a range from 6 to 17 bands, 153 of them were polymorphic, ranging from 97.27 to 100%. For SCoT analysis, 164 polymorphic bands (150–5000 bp) were observed, varying from 14 to 19 bands for each primer. Nei’s genetic diversity analysis showed that the highest value was found in P11 for ISSR and P4 for SCoT markers. The highest Nei’s genetic diversity value was observed in P5 for combined markers and the low in P2. Nei’s dendrogram constructed with combined markers indicated a 75–89% of genetic similarity coefficient among populations. Population structure analysis revealed an optimum number of three groups, the same as their geographical distribution. This knowledge on PR genetic diversity can be used in future breeding programs, genetic improvement, product enhancement, and germplasms conservation.

Sharma, Ritika; Kaur, Rajinder

doi: 10.1007/s11738-018-2754-0pmid: N/A

Fluoride is a common pollutant which occurs in various environmental matrices considered as one of the most phytotoxic pollutants. It is essential to the living organisms in trace quantities but at its higher concentration it becomes poisonous. Excess amount of fluoride in environment not only exerts its toxic effects on human beings and animals but also on plants. Toxicological impacts of fluoride on plants have been largely debated due to reduction of growth parameters, inhibition of metabolic activities and decreased photosynthetic activity. The signs of fluoride impacts on plants may be severe, acute or chronic and toxicity of fluoride depends on dose, frequency of exposure, duration and genotype of plant. This article overviews understanding of transport, uptake and fluoride accumulation in plants and provide insights into the fluoride-induced oxidative stress and regulatory mechanisms to cope up with it. The main objective of this article is to prospect new research avenues to unravel the mechanisms explaining fluoride toxicity in various plant species.

Hussain, Syed; Farooq, Muhammad; Akhtar, Javaid; Saqib, Zulfiqar

doi: 10.1007/s11738-018-2755-zpmid: N/A

Silicon is known to compensate crop yield losses under diverse biotic and abiotic stress conditions; however, reports about its protective role for plants exposed to brackish water stress are very limited. A pot culture experiment was conducted to assess the beneficial effect of silicon supplementation (0 and 100 mg/kg) in alleviating growth adversities of brackish water (saline, sodic, alkaline, and saline–sodic water) stress in two contrasting sunflower cultivars, SF-187 (salt tolerant), and Hysun-33 (salt sensitive) grown in greenhouse. Results demonstrated that hostile growth environments, mainly the combined stress of saline–sodic water, severely affected the physiological attributes, growth, yield, and yield contributing components in sunflower. However, the response to brackish water stress differed genotypically, with greater magnitude of damage to the Hysun-33 as compared to SF-187 genotype. It hampered plant growth due to membrane damage and reduced water uptake, but silicon supplementation minimized the negative effects of stress by limiting toxic Na+ ions uptake, improving membrane stability, and increasing relative water contents caused by higher silicon and K+ uptake that eventually led to improved biomass yield. The response was further evaluated at yield level and data regarding head diameter, achene yield, and 100 achene weight were taken. Results indicated that silicon supplementation to growth medium of saline and/or sodic water treated plants significantly enhanced the head diameter (22–30%), thus ultimately producing 15–25% higher achene yield, and weight of the biological harvest of both sunflower genotypes. Overall, the beneficial effect of silicon supplementation was more evident in Hysun-33 (salt sensitive) as compared to SF-187 (salt tolerant) genotype. Taken together, the results of this study suggest silicon fertilization as a potential strategy to increase crop productivity under brackish water stress; however, experimental trials at farmer field level should be conducted before setting any recommendations.

Miloš, Barták; Josef, Hájek; Jana, Morkusová; Kateřina, Skácelová; Alica, Košuthová

doi: 10.1007/s11738-018-2751-3pmid: N/A

In this study, we investigated responses of the Photochemical Reflectance Index (PRI), and Normalized Difference Vegetation Index (NDVI) to gradual dehydration of several Antarctic lichen species (chlorolichens: Xanthoria elegans, Rhizoplaca melanophthalma, Physconia muscigena, cyanolichen: Leptogium puberulum), and a Nostoc commune colony from fully wet to a dry state. The gradual loss of physiological activity during dehydration was evaluated by chlorophyll fluorescence parameters. The experimental lichen species differed in thallus color, and intrathalline photobiont. In the species that did not exhibit color change with desiccation (X. elegans), NDVI and PRI were more or less constant (mean of 0.25, − 0.36, respectively) throughout a wide range of thallus hydration status showing a linear relation to relative water content (RWC). In contrast, the species with apparent species-specific color change during dehydration exhibited a curvilinear relation of NDVI and PRI to RWC. PRI decreased (R. melanophthalma, L. puberulum), increased (N. commune) or showed a polyphasic response (P. muscigena) with desiccation. Except for X. elegans, a curvilinear relation was found between the NDVI response to RWC in all species indicating the potential of combined ground research and remote sensing spectral data analyses in polar regions dominated by lichen flora. The chlorophyll fluorescence data recorded during dehydration (RWC decreased from 100 to 0%) revealed a polyphasic species-specific response of variable fluorescence measured at steady state—F s, effective quantum yield of photosystem II (Φ PSII), and non-photochemical quenching (qN). Full hydration caused an inhibition of Φ PSII in N. commune while other species remained unaffected. The dehydration-dependent fall in Φ PSII was species-specific, starting at an RWC range of 22–32%. Critical RWC for Φ PSII was around 5–10%. Desiccation led to a species-specific polyphasic decrease in F s and an increase in qN indicating the involvement of protective mechanisms in the chloroplastic apparatus of lichen photobionts and N. commune cells. In this study, the spectral reflectance and chlorophyll fluorescence data are discussed in relation to the potential of ecophysiological processes in Antarctic lichens, their resistance to desiccation and survival in Antarctic vegetation oases.

Jin, Long-Fei; Guo, Da-Yong; Ning, Dong-yuan; Hussain, Syed; Liu, Yong-Zhong

doi: 10.1007/s11738-018-2761-1pmid: N/A

The persistent consumption of citrus fruit mainly depends on its sweet–sour taste as well as pulp texture. To date, the simple facility by covering plastic film just over trees is commonly used in different citrus species for harvest time extension and quality improvement. In this study, the effect of covering trees of Citrus reticulata cv. Kinokuni with plastic films was investigated. Results indicated that simply covering plastic film over trees significantly decreased the soil water content, the light intensity, and then the photosynthetic rate, however, moderately increased the internal average temperature of 0–3 °C. Moreover, it significantly facilitated soluble sugar accumulation, increased water soluble pectin content, and decreased protopectin content. Investigating transcript profile showed that only 351 gene transcripts were significantly influenced by covering plastic film. Interestingly, most differently expressed genes (DEGs) were involved in carbohydrate and cell wall metabolisms except some DEGs were related to signal transduction and environmental adaption. Taken together, covering plastic film over trees comprehensively modified the internal environmental condition and improved the fruit sweetness and mastication trait by promoting soluble sugar accumulation, increasing water soluble pectin content, and decreasing protopectin content through the alteration of transcript level.

Teng, Haiyan; Shen, Boran; Liu, Ee; Zhang, Jianjun; Peng, Xinxiang

doi: 10.1007/s11738-018-2753-1pmid: N/A

Although dozens of stress inducible promoters have been identified in rice, detailed and comparative investigations under uniform condition are still limited. In this study, we selected eight previously reported drought-inducible genes [Oshox24, hypothetical protein (hp), OsLEA3-1, OsNAC5, OsNCED3, Rab21, RRJ1 and Wsi18] and analyzed their transcriptional responses to drought and osmotic stresses in rice. Based on their transcription patterns and the required standards for inducible promoters, Oshox24, Rab21 and OsLEA3-1 were chosen for cloning of their promoters for detailed analyses at both the RNA and protein/activity levels, with rice oxalate oxidase gene (OsOxO3) as a reporter gene. By generating transgenic plants and determining oxalate oxidase activity that is activated under different stresses, we defined more quantitatively that the promoters of Oshox24, OsLEA3-1 and Rab21 are ideally applicable to transgene expression for inducibly controlling drought resistance genes or other functional genes in rice. The results provided a quantitative assessment of the strength, sensitivity, stress specificity and time course of the three promoters. Such detailed information is essential for the selection of promoters for use in improving stress resistance.

Lentini, Marco; De Lillo, Alessia; Paradisone, Valeria; Liberti, Daniela; Landi, Simone; Esposito, Sergio

doi: 10.1007/s11738-018-2752-2pmid: N/A

Cadmium represents one of the most toxic pollutants in plant ecosystems: at high concentrations it can cause severe effects, such as plant growth inhibition, decrease in photosynthesis and changes in plant basal metabolism. Changes in pigments’ content, RubisCO large subunit, and D1 protein indicated a severe reduction in photosynthetic efficiency. Furthermore, the decrease of nitrate reductase activity and changes in free amino acids levels show a general stress condition of nitrogen assimilation. Cadmium increased the activities of ROS scavenging enzymes; among these, ascorbate peroxidase rate was the most noticeably increased. It is worth noting that glucose-6-phosphate dehydrogenase (G6PDH; EC 1.1.1.64), showed changes in both activities and occurrence during cadmium stress. Interestingly, our data suggest that G6PDH would modulate redox homeostasis under metal exposure, and possibly satisfy the increased request of reductants to counteract the oxidative burst induced by cadmium. Therefore, the results suggest that APX and G6PDH may play a pivotal role to counteract the oxidative stress induced by cadmium in young barley plants.

Qiao, Qinghai; Wang, Xiaoying; Yang, Mengya; Zhao, Yingjia; Gu, Juntao; Xiao, Kai

doi: 10.1007/s11738-018-2758-9pmid: N/A

Plant miRNAs mediate diverse biological processes associating with growth, development, and environmental stress responses through regulating target genes at the posttranscriptional or translation level. In this study, TaMIR2275, a miRNA family member of wheat (T. aestivum), was subjected to functional characterization in mediation of the nitrogen (N) starvation response. TaMIR2275 targets eight genes that encode proteins involving various biological processes, including stress defense, transcriptional regulation, signaling transduction, and trafficking. Upon N starvation stress, TaMIR2275 showed gradually upregulated expression over a 24 h treatment and its induced transcripts were gradually restored along with a 24 h recovery treatment. In contrast, most of the target genes exhibited reverse expression pattern in response to the N starvation stress. These results suggest that the target genes are regulated by this miRNA largely through a cleavage mechanism. TaMIR2275 endowed plants improved growth features; the TaMIR2275 overexpression lines showed increased biomass and N accumulation whereas those with TaMIR2275 knockdown exhibited decreased biomass and plant N amount after N starvation compared with wild type. NtNRT2.1 and NtNRT2.2, two tobacco nitrate transporter (NRT) genes, showed modified expression in N-deprived TaMIR2275 overexpressors, suggesting their roles in modulation of the N acquisition. Transgene analysis confirmed these NRT genes to mediate the N uptake under N deprivation; the lines with NtNRT2.1 and NtNRT2.2 knockdwon displayed deteriorated growth, lowered N accumulation, and reduced biomass under N starvation treatment. Our results indicate that TaMIR2275 is essential in plant N deprivation response through transcriptional regulation of target genes that involve the N acquisition-associated process.