Vol 64, No 5 (2017)

Agrobacterial transformation is a main method of creation of transgenic plants under laboratory conditions. It is based on regeneration of whole plants from cells transformed with vectors based on T-DNA of agrobacteria. In addition, natural plants are described that contain T-DNA in their genomes and have been vertically transferring it throughout generations over millennia. This DNA was called cellular T-DNA (cT-DNA), and plants containing it are referred to as naturally transgenic ones. Since evolution involves manifold acts of such plant transformation, the latter appears to play important roles. This review analyzes the significance and feasible functions of cT-DNA in the evolution. Roles of cT-DNA in control of plant morphogenetic reactions and in that of processes related to plant-microbe interactions are also discussed.

This paper reports for the first time about the detection and identification of ginsenoside malonyl-Rg₁ (the rare 20(S)-protopanaxatriol-type ginsenoside) in the biomass of plant cell suspension culture of Japanese ginseng (Panax japonicus C.A. Mey. var. repens). Ginsenosides were analyzed by means of high-performance liquid chromatography/electrospray ionization mass spectrometry (HPLC-ESI-MS) in positive-ion mode. Malonyl-Rg1 was identified as a result of interpretation of MS spectra obtained upon fragmentation of protonated molecular ion ([M + H]⁺) of this compound in an ionization source. Chromatographic analysis and MS spectra showed that the cells of P. japonicus var. repens cultivated in vitro contain several isomers of malonyl-Rg₁. Thus, we ascertained for the first time that, in addition to malonyl ginsenosides of 20(S)-protopanaxadiol group, the plant cell culture of ginseng P. japonicus var. repens can accumulate glycosides of 20(S)-protopanaxatriol group acylated with a malonic acid residue. The obtained results showed that, in the cells of ginseng cultivated in vitro for a long time (for 10 years and more), the assortment of secondary metabolites (ginsenosides) may be as wide as in intact plants.

We investigated effects of sodium nitroprusside (SNP), the donor of nitric oxide (NO), on the growth and hormonal system of wheat plants (Triticum aestivum L.) in normal conditions and after salt stress (2% NaCl). During germination of seeds treated with SNP (50–500 μM), we obtained the SNP concentration (200 μM) optimal for stimulation of seedling growth estimated by increase in seed germination capacity and seedlings' linear sizes and their fresh and dry biomass. A comparative analysis of SNP (200 μM) effects, after seed germination in the medium with SNP or pretreatment of 3-day-old seedlings, showed SNP ability to increase the wheat plant resistance to subsequent effects of sodium chloride salinity at both treatment methods. Protective SNP effects appeared in the reduction of stress inhibitory action on seedling growth rates and significant reduction in the level of lipid peroxidation and exosmosis of electrolytes. An important contribution to realization of the growth-stimulating and protective effects of NO is associated with its ability to influence the state of the hormonal system of wheat plants due to an increase in the concentration of hormones of a cytokinin nature under normal conditions and the prevention of a decrease in their level under stress.

The common wheat (Triticum aestivum L.) three-pistil (TP) mutant produces three pistils in a floret, consequently, forms three grains after pollination. It has potential to increase yields and also a significant genetic material to study floral development. Research on the genetic mechanisms determining of TP floral organ development has a potential prospect for wheat breeding. In this study, four WAG-2 transcripts, named WAG-2l, WAG-2m, WAG-2n and WAG-2o were isolated from TP and characterized. They were highly conserved in the MADS-domain and I-region while two distinct sequence divergences were detected in K-domain and C-region. The four WAG-2 transcripts could be divided into two groups resulted from splicing events with alternative 5′ splice site selection of exon 4. The expression levels of each WAG-2 transcript in Chinese Spring (CS) were approximately 1.5 and 74.5-fold higher than that in near-isogenic CSTP lines derived from wheat three-pistil mutant/Chinese Spring)//Chinese Spring. At anther separation stage, WAG-2n (the splicing variant 2) played a vital role in CS, while WAG-2m (the splicing variant 1) was highly expressed in CSTP. The alteration of expression of four WAG-2 transcripts were at least partly associated with the threepistil trait. The expression levels of four WAG-2 transcripts were highest at anther separation stage to tetrad stage, particularly in pistil development suggesting that they function in pistil development and maturation rather than in differentiation. These findings enrich the understanding of the molecular mechanism controlling the TP trait and WAG-2 gene function.

Efficient photosynthesis is critical for plant survival and growth. When plant-absorbed light exceeds the overall rate of energy conversion, it will trigger photooxidation. In this study, we selected a photooxidation mutant 812HS, it was isolated from the progeny of japonica rice (Oryza sativa L.) 812S and shows leaf yellowing and hypersensitive to photooxidation. Chloroplast ultrastructure in the leaves of 812HS showed that photooxidation resulted in significant chloroplast damage compared with 812S for changes in gene expressions in response to photooxidation stress using next-generation sequencing technologies on an Illumina HiSeq 2000 platform. A total of 88508 and 88495 genes were identified from 812S and 812HS, respectively. Expressions of 1199 genes were significantly upregulated, while 1342 genes were remarkably downregulated in 812HS. These genes were notably enriched in the 21 KEGG pathways. Based on their expression patterns, several key pathways were identified to be involved in the photooxidation of 812HS. qRT-PCR analysis further confirmed the results of RNA-Seq. This study enabled us to integrate analysis of RNA-Seq in rice and offered a deeper insight into the molecular mechanisms in response to photo-oxidative stress and provided clues for further critical gene identification in the protective mechanisms against photooxidation.

The R1 gene for resistance to oomycete Phytophthora infestans (Mont.) de Bary, the causal agent of late blight disease of potato (Solanum tuberosum L.), was initially identified in S. demissum and potato varieties bred by introgressing the S. demissum germplasm. Later a sequence characterized amplified region (SCAR) marker R1-1205 of this gene was also found in S. stoloniferum and S. polytrichon. Here we describe the full-length R1 sequence cloned from S. stoloniferum. This sequence is translatable, and this evidence of structural gene integrity is reinforced by functional characterization of the S. stoloniferumR1 gene in an effectoromics experiment. When screened across a series of S. demissum and S. stoloniferum accessions, the R1 sequences differed by several single nucleotide polymorphisms and an indel; this indel served the basis for constructing SCAR markers R1-517 and R1-513 that reliably discerned two R1 orthologs. The demissum-specific marker R1-517 was found in all S. demissum accessions under study; it was also present in many demissum-derived potato varieties and hybrids. The stoloniferum-specific marker R1-513 was found in 27% of S. stoloniferum and S. polytrichon accessions; however, we failed to discern this marker in the genotypes of cultivated potato listing S. stoloniferum in their pedigrees. Most probably, such absence of R1-513 is best explained by an opportunistic breeding history of stoloniferum-derived founder lines, which were employed first and foremost in breeding for resistance to potato virus Y: eventually, these founder lines are devoid of the R1 gene.

Mulberry (Morus alba L.) is a kind of plant with strong adaptation to drought, salt stress, water logging, and other environmental stresses. However, there is little knowledge on the molecular mechanism involved in its response and resistance to environmental stresses, including salt stress. In this study, a total of 101589 unigenes were obtained from 24 Morus salinity subtranscriptomes using Illumina RNA-sequencing technology, and led to 34.72% of the assembled reads being matched to known transcripts. The number of down-regulated DEGs (differentially expressed genes) under salt stress is more than that of up-regulated DEGs, and these down-regulated DEGs enriched in the process related to stress response by GO and KEGG enrichment analysis. It is notable that some genes showed diverse response patterns against salt stress in genotype- and tissue-dependent manners. The DEGs involved in signal transduction and transcription regulation were found to be more enriched in low-salt-tolerant genotypes and the majority of these responsive genes showed decreased transcript abundance, which may result in low tolerance of low-salt-tolerant genotypes. The results of this study will advance our understanding of the salt response in Morus and provide the basis for further genetic improvement of salt tolerance in Morus and other plants.

Identifying a potential crop wild relative (CWR) of legumes, especially one with high abiotic stress tolerance, has been a priority of plant breeders for many decades. Traditionally CWRs have been selected based on biometrical traits observed in the field, however this methodology is insufficient for research into nonmorphological traits such as stress tolerance. Biochemical and molecular analysis of potential CWRs allows for more informed selection. Specifically, we focus on Cicer microphyllum Benth, a CWR of cultivated chickpea Cicer arietinum L., which is distributed in Trans Himalayan ranges adjacent to glaciers of India and Pakistan at the alpine altitude gradient between 2700 to 6000 m. The objective of this study is to begin characterization of the biochemical and molecular bases of adaptation of C. microphyllum to cold stress and compare it to its cultivated relative (Cold susceptible genotype ILC533). Significant differences were recorded in terms of malondialdehyde (MDA) concentration, electrolyte leakage and proline accumulation in C. microphyllum, as compared to C. arietinum, upon cold exposure (4°C/24h). C. microphyllum exhibits more membrane stability under cold stress. Furthermore, proline overaccumulation and an increase in the enzymatic activities of antioxidants including superoxide dismutase, catalase, and ascorbate peroxidase were also observed in C. microphyllum under cold stress treatment. Expression of pyrroline-5-carboxylate synthetase, chalcone reductase, flavonoid 3',5'-hydroxylase and flavonoid 3'-monooxygenase are all upregulated under cold treatment in C. microphyllum. The characteristics recommend C. microphyllum both as a model for plant response to cold stress and as a potential source for abiotic stress resistant germplasm for chickpea breeding programs.

The experiments were conducted with 10-day-old seedlings of wheat (Triticum aestivum L). Phytochrome B was activated using an array of light diodes emitting light in the red spectral region (RL) and inactivated by an array of light diodes emitting far-red light (FRL). At the end of the night dark period (8 h), activity of the chloroplastic GAP-dehydrogenase complex (the sequence of reactions: 3-PGA → 1,3-PGA → 3-GAP) was 1.0−1.2 μmol of oxidized NADPH/(min g fr wt of the leaf). When the leaves of intact plants were exposed to a maximal dose of RL (20 min at 17.5 kJ/m²), enzyme activity rose by 100–120%. Longer exposure to RL (30 and 40 min) did not cause further activation. Successive exposure to RL and FRL (20 min at 3.0 kJ/m²) completely negated a stimulatory effect of RL. It was shown that as little as 5-min-long exposure to RL increased the rate of 3-GAP formation by 20–25%, and enzyme activity rose linearly when radiation dose was elevated. Determination of the lifetime of RL-activated state by its decrease in plants placed in darkness showed that decay occurred with τ_1/2 of 50−60 min when RL was switched off. Thus, a phytochrome B-induced regulation of reducing enzyme complex governing the reductive pentose phosphate cycle was discovered. Judging from the kinetics of attenuation of the activated state, phytochrome B apparently does not affect de novo synthesis of the enzyme. Since the investigated metabolic process consists of two coupled reactions controlled by kinase and dehydrogenase, the place and mechanism of action of the phytochrome system remain unknown.