Plants constantly suffer from simultaneous infection by multiple pathogens, which can be divided into biotrophic, hemibiotrophic, and necrotrophic pathogens, according to their lifestyles. Many studies have contributed to improving our knowledge of how plants can defend against pathogens, involving different layers of defense mechanisms. In this sense, the review discusses: (1) the functions of PAMP (pathogen-associated molecular pattern)-triggered immunity (PTI) and effector-triggered immunity (ETI), (2) evidence highlighting the functions of salicylic acid (SA) and jasmonic acid (JA)/ethylene (ET)-mediated signaling pathways downstream of PTI and ETI, and (3) other defense aspects, including many novel small molecules that are involved in defense and phenomena, including systemic acquired resistance (SAR) and priming. In particular, we mainly focus on SA and (JA)/ET-mediated signaling pathways. Interactions among them, including synergistic effects and antagonistic effects, are intensively explored. This might be critical to understanding dynamic disease regulation.

Although rapeseed (Brassica napus L.) mutant forming multiple siliques was morphologically described and considered to increase the silique number per plant, an important agronomic trait in this crop, the molecular mechanism underlying this beneficial trait remains unclear. Here, we combined bulked-segregant analysis (BSA) and whole genome re-sequencing (WGR) to map the genomic regions responsible for the multi-silique trait using two pools of DNA from the near-isogenic lines (NILs) zws-ms (multi-silique) and zws-217 (single-silique). We used the Euclidean Distance (ED) to identify genomic regions associated with this trait based on both SNPs and InDels. We also conducted transcriptome sequencing to identify differentially expressed genes (DEGs) between zws-ms and zws-217. Genetic analysis using the ED algorithm identified three SNP- and two InDel-associated regions for the multi-silique trait. Two highly overlapped parts of the SNP- and InDel-associated regions were identified as important intersecting regions, which are located on chromosomes A09 and C08, respectively, including 2044 genes in 10.20-MB length totally. Transcriptome sequencing revealed 129 DEGs between zws-ms and zws-217 in buds, including 39 DEGs located in the two abovementioned associated regions. We identified candidate genes involved in multi-silique formation in rapeseed based on the results of functional annotation. This study identified the genomic regions and candidate genes related to the multi-silique trait in rapeseed.

Decreasing saturated fatty acids and increasing monounsaturated fatty acids are desirable to improve oil for food. Seed oil content and fatty acid composition are affected by genotype and environment. Therefore, we systematically analyzed the agronomic traits and fatty acid metabolic profiling of Brassica napus (B. napus) seeds at different developmental stages in high level of oleic acid (HOA), medium level of oleic acid (MOA), and low level of oleic acid (LOA) B. napus cultivars, both sown in winter and summer. The results showed that all winter-sown cultivars produced 20% more seed yield than the summer-sown crop. The longer growing period of winter-sown B. napus resulted in higher biomass production. However, the fatty acid metabolism of individual cultivars was different between winter-sown rape (WAT) and summer-sown rape (SAT). The absolute fatty acid content of LOA and MOA cultivars in WAT were significantly higher than that in SAT, but that of HOA was opposite. Importantly, the levels of monounsaturated fatty acids (18:1; 20:1) in SAT were far more than those in WAT. These data indicate the quality of oil from the HOA in SAT is more suitable for human consumption than that in WAT.

Plant height is a vital agronomic trait for crops, including oilseed crops such as rapeseed (Brassica napus L.). It affects the crop yield, oil content, and lodging resistance in rapeseed. In this study, we investigated a dwarf trait controlled by a semi-dominant allele in rapeseed. A dwarf line, YA2016-12, was crossed with a tall line, G184-189, and an F2 population was established. Forty of the tallest plants and 40 of the shortest plants from the F2 population were selected and two DNA pools (tall and dwarf) were constructed by the bulked segregant analysis (BSA) method. The two DNA pools and two parental DNAs were then re-sequenced. A sliding window analysis was used to calculate the Δ(SNP-index) and discover an association region on chromosome A03 with a length of 12.4 Mb. Within this region, we found 1225 genes, including 811 genes with non-synonymous or frameshift mutations between YA2016-12 and G184-189. Alignment to known plant height-related orthologs in Arabidopsis thaliana, as well as KEGG pathway and gene ontology annotations, was used to identify nine candidate genes (BnaA03g31770D, BnaA03g37960D, BnaA03g24740D, BnaA03g40550D, BnaA03g26120D, BnaA03g35130D, BnaA03g42350D, BnaA03g25610D, and BnaA03g39850D) involved in gibberellin or cytokinin signaling. Identification of the causal gene for this trait, and of genetic markers linked to favorable alleles, has potential utility for marker-assisted selection to breed rapeseed varieties with improved height.

Leaf is an important organ for higher plants, and the shape of it is one of the crucial traits of crops. In this study, we investigated a unique aberrant leaf morphology trait in a mutational rapeseed material, which displayed ectopic blade-like outgrowths on the adaxial side of leaf. The abnormal line 132000B-3 was crossed with the normal line 827-3. Based on the F_2:3 family, we constructed two DNA pools (normal pool and abnormal pool) by the bulked segregant analysis (BSA) method and performed whole genome re-sequencing (WGR), obtaining the single-nucleotide polymorphism (SNP) and insertion/deletion (InDel) data. The SNP-index method was used to calculate the Δ(SNP/InDel-index), and then an association region was identified on chromosome A10 with a length of 5.5 Mbp, harboring 1048 genes totally. Subsequently, the fine mapping was conducted by using the penta-primer amplification refractory mutation system (PARMS), and the associated region was narrowed down to a 35.1-kbp segment, containing only seven genes. These seven genes were then analyzed according to their annotations and finally, BnA10g0422620 and BnA10g0422610, orthologs of LATE MERISTEM IDENTITY1 (LMI1) gene from Arabidopsis and REDUCED COMPLEXITY (RCO) gene from its relative Cardamine hirsuta, respectively, were identified as the candidate genes responding to this blade-like outgrowth trait in rapeseed. This study provides a novel perspective into the leaf formation in Brassica plants.

The CLE (CLAVATA3/EMBRYO SURROUNDING REGION-related) small peptides constitute a large supergene family in plants and are extensively involved in plant stress responses and the regulation of growth and development. Light, water, gravity, and mechanical trauma play critical roles in maintaining normal plant growth and development; however, there have been no reports as to whether CLE genes are involved in the responses of sesame to these forms of stress. In this study, the CLE gene family in Zhongzhi No. 13 was systematically identified. Stress induction was performed using light and gravity, and the expression patterns in various tissues and organs were analyzed by means of transcriptome sequencing. Concurrently, the water stress response published in the NCBI database was queried and analyzed. The results showed that a total of 12 SiCLE genes exist in the genome of Zhongzhi No. 13, distributed on six chromosomes. Each gene encodes a signal peptide at its N-terminus and a conserved motif at its C-terminus. The majority of SiCLE genes exhibit a single-exon structure. The SiCLE genes encode proteins ranging from 72 to 133 amino acids in length. Most of these proteins are basic, hydrophobic, and unstable. An analysis of promoter cis-acting elements revealed that the majority of SiCLE gene family members harbor response elements associated with light, phytohormones, stress, and growth and development. Transcriptome analysis revealed that SiCLE4, SiCLE5, SiCLE8, and SiCLE10 exhibit differential expression under water stress, light stress, and gravity stress/mechanical damage conditions. These results provide a solid foundation for future investigations aimed at elucidating the biological roles of the CLE gene family in both abiotic stress responses and the regulation of growth and development.