bims-pisump 2018-05-20 papers

Issue of 2018‒05‒20
four papers selected by
Vera S. Bogdanova
Institute of Cytology and Genetics, Siberian Branch of the Russian Academy of Sciences

Mol Cells. 2018 May 10.

Confirmation of Drought Tolerance of Ectopically Expressed AtABF3 Gene in Soybean.

Hye Jeong Kim, Hyun Suk Cho, Jung Hun Pak, Tackmin Kwon, Jai-Heon Lee, Doh-Hoon Kim, Dong Hee Lee, Chang-Gi Kim, Young-Soo Chung.

Soybean transgenic plants with ectopically expressed AtABF3 were produced by Agrobacterium-mediated transformation and investigated the effects of AtABF3 expression on drought and salt tolerance. Stable Agrobacterium-mediated soybean transformation was carried based on the half-seed method (Paz et al. 2006). The integration of the transgene was confirmed from the genomic DNA of transformed soybean plants using PCR and the copy number of transgene was determined by Southern blotting using leaf samples from T2 seedlings. In addition to genomic integration, the expression of the transgenes was analyzed by RT-PCR and most of the transgenic lines expressed the transgenes introduced. The chosen two transgenic lines (line #2 and #9) for further experiment showed the substantial drought stress tolerance by surviving even at the end of the 20-day of drought treatment. And the positive relationship between the levels of AtABF3 gene expression and drought-tolerance was confirmed by qRT-PCR and drought tolerance test. The stronger drought tolerance of transgenic lines seemed to be resulted from physiological changes. Transgenic lines #2 and #9 showed ion leakage at a significantly lower level (P < 0.01) than nontransgenic (NT) control. In addition, the chlorophyll contents of the leaves of transgenic lines were significantly higher (P < 0.01). The results indicated that their enhanced drought tolerance was due to the prevention of cell membrane damage and maintenance of chlorophyll content. Water loss by transpiration also slowly proceeded in transgenic plants. In microscopic observation, higher stomata closure was confirmed in transgenic lines. Especially, line #9 had 56% of completely closed stomata whereas only 16% were completely open. In subsequent salt tolerance test, the apparently enhanced salt tolerance of transgenic lines was measured in ion leakage rate and chlorophyll contents. Finally, the agronomic characteristics of ectopically expressed AtABF3 transgenic plants (T2) compared to NT plants under regular watering (every 4 days) or low rate of watering condition (every 10 days) was investigated. When watered regularly, the plant height of droughttolerant line (#9) was shorter than NT plants. However, under the drought condition, total seed weight of line #9 was significantly higher than in NT plants (P < 0.01). Moreover, the pods of NT plants showed severe withering, and most of the pods failed to set normal seeds. All the evidences in the study clearly suggested that overexpression of the AtABF3 gene conferred drought and salt tolerance in major crop soybean, especially under the growth condition of low watering.

DOI: https://doi.org/10.14348/molcells.2018.2254

Mol Plant. 2018 May 09. pii: S1674-2052(18)30160-6. [Epub ahead of print]

The Antagonistic Action of Abscisic Acid and Cytokinin Signaling Mediates Drought Stress Response in Arabidopsis.

Xiaozhen Huang, Lingyan Hou, Jingjing Meng, Huiwen You, Zhen Li, Zhizhong Gong, Shuhua Yang, Yiting Shi.

As sessile organisms, plants encounter a variety of environmental stresses and must optimize their growth for survival. Abscisic acid (ABA) and cytokinin antagonistically regulate many developmental processes and environmental stress responses in plants. However, the molecular mechanism underlying the antagonism remains poorly defined. In this study, we demonstrated that Sucrose nonfermenting1-related kinases SnRK2.2/2.3/2.6, the key kinases of ABA signaling pathway, directly interacted with and phosphorylated type-A response regulator 5 (ARR5), a negative regulator in cytokinin signaling. The phosphorylation of ARR5 at Ser residues by SnRK2s enhanced ARR5 protein stability. Accordingly, overexpression of ARR5 showed ABA hypersensitivity and drought tolerance, which could not be recapitulated by mimic non-phosphorylated ARR5. Moreover, type-B ARR1, 11, and 12 physically interacted with SnRK2s and repressed the kinase activity of SnRK2.6. The arr1,11,12 triple mutant exhibited hypersensitivity to ABA. Genetic analysis demonstrated that SnRK2s act upstream of ARR5 and downstream of ARR1,11,12 in mediating ABA response and drought tolerance. Together, this study unravels the antagonistic action underlying ABA and cytokinin signaling pathways, thus providing insights into how plants coordinate growth and stress response by integrating multiple hormone pathways under drought stress.

Keywords: Arabidopsis; SnRK2s; drought stress; type-A ARR5; type-B ARRs

DOI: https://doi.org/10.1016/j.molp.2018.05.001

Mol Phylogenet Evol. 2018 May 10. pii: S1055-7903(17)30464-5. [Epub ahead of print]

Chloroplast phylogeny of AA genome rice species.

Ali Mohammad Moner, Agnelo Furtado, Robert J Henry.

Whole chloroplast genome sequence analysis of 58 wild and domesticated rice samples was used to investigate their phylogeny providing more detail on the biogeography of the major groups of wild A genome rices globally. An optimized chloroplast assembly method was developed and applied to extracting high quality whole chloroplast genome sequences from shot gun whole DNA sequencing data. Forty complete high quality chloroplast genome sequences were assembled (including; temperate japonica, tropical japonica and aus). The South American and African wild rice relationships were confirmed, while the Australian chloroplast type was found to extend north to the Philippines. The remainder could be divided into an African (O. barthii and the domesticated O. glaberrima) clade and the Asian taxa. The Asian taxa were placed in two distinct clades including the domesticated O. sativa ssp. indica and O. sativa ssp. japonica respectively. These two groups of wild rices had substantially overlapping distributions with the O. sativa japonica group extending further west into India. The aromatic rices had japonica chloroplasts as expected. A polyphyletic maternal genome origin of the cultivated aus group of rices was suggested by the identification of aus accessions in both the wild indica and japonica clades. The current distribution of the chloroplast types appears to differ significantly to that of the nuclear genome diversity suggesting a complex evolutionary history of the rice progenitors leading to the domestication of rice.

Keywords: Asian wild rice; OryzaAA genome; chloroplast sequence; de novo assembly; mapping assembly; phylogenetic analysis

DOI: https://doi.org/10.1016/j.ympev.2018.05.002

Food Chem Toxicol. 2018 May 10. pii: S0278-6915(18)30287-4. [Epub ahead of print]

The problem of misidentification between edible and poisonous wild plants: Reports from the Mediterranean area.

L Cornara, A Smeriglio, J Frigerio, M Labra, E Di Gristina, M Denaro, E Mora, D Trombetta.

Today, in many European countries, people are looking for wild edible plants to experience new tastes and flavors, by following the new trend of being green and environmentally friendly. Young borage and spinach leaves can be easily confused by inexpert pickers with those of other plants, including poisonous ones, such as Mandragora autumnalis Bertol. (mandrake) or Digitalis purpurea L. (foxglove), common in southern and northern Italy respectively. In the last twenty years, several cases of intoxication by accidental ingestion of mandrake and foxglove have been reported. The purpose of this work was to perform a pharmacognostic characterization of young leaves from borage, mandrake, foxglove and spinach, by micro-morphological, molecular and phytochemical techniques. The results showed that each of the three techniques investigated could be sufficient alone to provide useful information for the identification of poisonous species helping the medical staff to manage quickly the poisoned patients. However, the multi-disciplinary approach proposed could be very useful to asses the presence of poisonous plants in complex matrices, to build a database containing morphological, molecular and phytochemical data for the identification of poisonous species or in forensic toxicology, given their increasingly frequent use due to their low cost and relatively common availability.

Keywords: Accidental ingestion; Discriminant analyses; Edible plants; Intoxication; Plant leaves; Poisonous plants

DOI: https://doi.org/10.1016/j.fct.2018.04.066