Biology subjects

Fridmanis, D.

Publications and source records attributed to Fridmanis, D..

3 recordsLinked to original sources

bioRxiv2026

Characterization of mycobiota in faba beans infected with Alternaria spp.

Leaf diseases pose a serious threat to faba bean production. Leaf blotch of faba bean, caused by Alternaria spp., has become increasingly widespread and destructive in several countries. Leaf diseases pose a serious threat to faba bean production. The infection of plant by pathogens can be influenced by various factors associated with the host plant, environmental conditions and presence of other microorganisms. The phyllosphere and endosphere play a critical role in plant health and disease development. This study aimed to evaluate the factors shaping the structure and diversity of fungal communities associated with faba beans. Plant samples were collected in 2004 from two intensively managed faba bean production fields in the central region of Latvia. Fungal assemblages were characterized using an ITS region metabarcoding approach based on Illumina MiSeq sequencing. Among the assigned amplicon sequence variant (AVS), 65% belonged to the phylum Ascomycota, while approximately 4% were classified as Basidiomycota. Alternaria and Cladosporium were the dominant genera across samples. The alfa and beta diversities of fungal communities was higher during flowering of faba beans to compare with ripening. The higher abundance of Basidiomycota yeasts were observed during flowering, in contrast, Cladosporium genus was significantly more abundant during ripening. Alternaria DNA was found on leaves that showed no symptoms of the disease. The diversity and composition of fungal communities were significantly influenced by sampling time and presence of leaf blotch, caused by Alternaria spp.

microbiology↗

bioRxiv2023

Ryegrass mottle virus complete genome determination and development of infectious cDNA by combining two methods - 3' RACE and 5' RACE-seq

Sobemovirus ryegrass mottle virus (RGMoV) is a single-stranded positive virus with a 30 nm viral particle size. It exhibits T=3 symmetry, with 180 coat protein (CP) subunits forming the virus structure. The RGMoV genome comprises five open reading frames, encoding P1, Px, a membrane-anchored 3C-like serine protease, a virus genome-linked protein, P16, an RNA-dependent RNA polymerase, and a coat protein. The RGMoV genome size varies, ranging from 4175 nt (MW411579.1) to 4253 nt (MW411579.1) in deposited sequences. An earlier deposited RGMoV complete genome sequence of 4212 nt length (EF091714.1) was utilized to develop an infectious complementary DNA (icDNA) construct for in vitro gRNA transcription from the T7 promoter. However, when the transcribed gRNA was introduced to oat plants, it failed to induce viral infection. This indicated the potential absence of certain sequences in either the 5 or 3 untranslated regions (UTR) or both. To resolve this, the complete sequence of the 3 UTR was determined through 3 end RACE, while the 5 UTR was identified using high-throughput sequencing (HTS) - 5 RACE-seq. Only the icDNA vector containing both newly identified UTR sequences proved infectious, resulting in classical viral infection symptoms and subsequent propagation of progeny viruses, exhibiting the ability to cause repeated infection in oat plants after at least one passage. The successful generation of the icDNA highlights the synergistic potential of utilizing both methods when one approach alone fails. Furthermore, this study demonstrates the reliability of HTS as a method for determining the complete genome sequence of viral genomes.

molecular biology↗

bioRxiv2022

OverFlap PCR - a reliable approach for generation of plasmid DNA libraries containing random sequences without template bias.

Over the decades the improvement of naturally occurring proteins and creation of novel ones has been the primary goal for many practical biotechnology researchers and it is widely recognized that randomization of protein sequences coupled to various effect screening methodologies is one of the most powerful techniques for fast, efficient and purposeful approach for acquisition of desired improvements. Over the years considerable advancements have been made in this field, however development of PCR based or template guided methodologies has been hampered by the resulting template sequence bias. In this article we present novel whole plasmid amplification based approach, which we named OverFlap PCR, for randomization of virtually any region of the plasmid DNA, without introduction of mentioned bias.

molecular biology↗