Drought is one of the major factors limiting global maize production. Exposure to long-term drought conditions inhibits growth and leads to yield losses. Although several drought-responsive genes have been identified and functionally analyzed, the mechanisms underlying responses to drought and water recovery treatments have not been fully elucidated. To characterize how maize seedling respond to drought stress at the transcriptional level, we analyzed physiological responses and differentially expressed genes (DEGs) in the inbred line B73 under water deficit and recovery conditions. The data for relative leaf water content, leaf size, and photosynthesis-related parameters indicated that drought stress significantly repressed maize seedling growth. Further RNA sequencing analysis revealed that 6107 DEGs were responsive to drought stress and water recovery, with more down-regulated than up-regulated genes. Among the DEGs, the photosynthesis- and hormone-related genes were enriched in responses to drought stress and re-watering. Additionally, transcription factor genes from 37 families were differentially expressed among the three analyzed time-points. Gene ontology enrichment analyses of the DEGs indicated that 50 GO terms, including those related to photosynthesis, carbohydrate metabolism, oxidoreductase activities, nutrient metabolism and other drought-responsive pathways, were over-represented in the drought-treated seedlings. The content of gibberellin in drought treatment seedlings was decreased compared to that of control seedlings, while abscisic acid showed accumulated in the drought treated plants. The deep analysis of DEGs related to cell wall development indicated that these genes were prone to be down-regulated at drought treatment stage. Many genes that are differentially expressed in responses to drought stress and water recovery conditions affect photosynthetic systems and hormone biosynthesis. The identified DEGs, especially those encoding transcription factors, represent potential targets for developing drought-tolerant maize lines.

Brassica yellows virus (BrYV) is an economically important virus on cruciferous species. In this study, a one-pot reverse transcription loop-mediated isothermal amplification (RT-LAMP) assay coupled with the clustered regularly interspaced short palindromic repeats (CRISPR)/Cas12a system was developed for the detection of BrYV. The limit of detection of this method reached 32.8 copies of the BrYV ORF5, which is 100-fold more sensitive than the RT-LAMP method. Moreover, there was no cross-reactivity with other rapeseed-infecting RNA viruses or poleroviruses. We dried the CRISPR/Cas12a reagent in a trehalose and pullulan mixture to retain its efficacy at the RT-LAMP temperature of 63°C in order to allow portable BrYV detection in a water bath. The entire process can be performed in about 1 h, and a positive result can be rapidly and conveniently detected using a handheld UV lamp. In the field, the RT-LAMP-CRISPR/Cas12a assay was accurate and had higher sensitivity than RT-LAMP and reverse transcription–polymerase chain reaction assays. The novel RT-LAMP-CRISPR/Cas12a assay allows convenient, portable, rapid, low-cost, highly sensitive, and specific detection of BrYV and has great potential for on-site monitoring of BrYV.

The emergence of brassica yellow virus (BrYV) has increasingly damaged crucifer crops in China in recent years. In 2020, a large number of oilseed rape in Jiangsu showed aberrant leaf color. A combined RNA-seq and RT-PCR analysis identified BrYV as the major viral pathogen. A subsequent field survey showed that the average incidence of BrYV was 32.04%. In addition to BrYV, turnip mosaic virus (TuMV) was also frequently detected. As a result, two near full-length BrYV isolates, BrYV-814NJLH and BrYV-NJ13, were cloned. Based on the newly obtained sequences and the reported BrYV and turnip yellow virus (TuYV) isolates, a phylogenetic analysis was performed, and it was found that all BrYV isolates share a common root with TuYV. Pairwise amino acid identity analysis revealed that both P2 and P3 were conserved in BrYV. Additionally, recombination analysis revealed seven recombinant events in BrYV as TuYV. We also attempted to determine BrYV infection by quantitative leaf color index, but no significant correlation was found between the two. Systemic observations indicated that BrYV-infected plants had different symptoms, such as no symptom, purple stem base and red old leaves. Overall, our work proves that BrYV is closely related to TuYV and could be considered as an epidemic strain for oilseed rape in Jiangsu.

Poleroviruses are positive-sense, single-stranded viruses. In this study, we describe the identification of a novel polerovirus isolated from soybean displaying curled leaves. The complete viral genome sequence was identified using high-throughput sequencing and confirmed using rapid amplification of cDNA ends (RACE), RT-PCR and Sanger sequencing. Its genome organization is typical of the members of genus Polerovirus, containing seven putative open reading frames (ORFs). The full genome is composed of single-stranded RNA of 5822 nucleotides in length, with the highest nucleotide sequence identity (79.07% with 63% coverage) for cowpea polerovirus 2 (CPPV2). Amino acid sequence identities of the protein products between the virus and its relatives are below the threshold determined by the International Committee of Taxonomy of Viruses (ICTV) for species demarcation, and this strongly supports this virus’ status as a novel species, for which the name soybean chlorotic leafroll virus (SbCLRV) is proposed. Recombination analysis identified a recombination event in the ORF5 of the 3’ portion in the genome. Phylogenetic analyses of the genome and encoded protein sequences revealed that the new virus is closely related to phasey bean mild yellows virus, CPPV2 and siratro latent polerovirus. Subsequently, we demonstrated the infectivity of SbCLRV in Nicotiana benthamiana via infectious cDNA clone generation and agroinoculation.

The plant height of rapeseed is one of the important factors that affects the production of rapeseed. If the plant height of rapeseed is too high, on the one hand, it will cause rapeseed to lodge and affect the yield, on the other hand, it will also affect the mechanized harvesting of rapeseed. In this research, the high-stalked line (YY50) and the dwarfed line (DW871) are crossed to obtain an F2 rapeseed population which was used to build pools, and then we used this to mine the main dwarfing genes. In the pools composed of tall and short stalks, we obtained 192.80Mb clean reads, which can be used for BSA (bulked segregant analysis). Preliminary positioning around the candidate section identified 23 SNP markers. Then 17 polymorphic SNP markers were obtained through polymorphism screening. Further we narrowed the candidate interval, and finally determined between 15.51-16.60Mb of ChrA10. Through identifying 231 genes from the above interval, it’s predicted that the production of dwarf traits may be related to lignin synthesis and limited inflorescence. It provides a basis for further mapping and cloning of the dwarfing gene DW871.

Mixed viral infections are common in the field but are rarely studied due to their inherent complexity. Here, we observed a mixed infection of brassica yellows virus (BrYV) and turnip mosaic virus (TuMV) in oilseed rape (Brassica napus L.). Therefore, this study explores the relationships between two viruses based on newly constructed infectious clones of BrYV-GZA, BrYV-GZB, and a previously reported TuMV-GFP clone. Our results demonstrate that BrYV-GZA significantly inhibited TuMV in Nicotiana benthamiana (N. benthamiana). In contrast, BrYV-GZB was a mild strain, which exhibited a delayed onset time and less influence on TuMV. In oilseed rape, the incidence of TuMV was significantly lower in plants co-infected with BrYV-GZA and TuMV (AT) than in those infected with TuMV alone (p = 0.015). Besides, TuMV failed to infect oilseed rape plants pre-inoculated with BrYV-GZA. Furthermore, RNA silencing suppressors of HC-Pro and P0 were found promote the accumulation of BrYV-GZA and TuMV accumulation, respectively. Symptom analysis showed that both BrYV-GZA single infection and AT double infection significantly reduced the plant height of oilseed rape. Additionally, these infections led to a 3% and 7% decrease in oil content of rapeseed, respectively. AT double infection also altered fatty acid composition, resulting in significant decreases in both oleic acid and stearic acid, and an increase in linoleic acid. Overall, our findings reveal an asymmetric interaction between BrYV-GZA and TuMV in both N. benthamiana and oilseed rape, highlighting the effects of mixed infections on agronomic traits of oilseed rape.