From Nasty to Tasty: Some of our favorite food crops derive from wild relatives that were distasteful or even toxic. Domestication over many years selected for variants with reduced levels of antinutritional compounds. The wild relatives remain valuable, however, for other traits such as resistance to pathogens, but their use in crop development is complicated by the continued presence of unpalatable compounds.
Itkin
et al. (p. 175 , published online 20 June) elucidate the metabolic pathways and genes directing synthesis of some of these antinutritionals in potato and tomato.
Summary: Early blight (EB), caused by Alternaria solani, is a major threat to global tomato production. In comparison with cultivated tomato (Solanum lycopersicum), a wild relative, S. arcanum exhibits strong resistance against EB. However, molecular cascades operating during EB resistance in wild or cultivated tomato plants are largely obscure. Here, we provide novel insight into spatio‐temporal molecular events in S. arcanum against A. solani. Transcriptome and co‐expression analysis presented 33‐WRKYs as promising candidates of which 12 SaWRKYs displayed differential expression patterns in resistant and susceptible accessions during EB disease progression. Among these, SaWRKY1 exhibited induced expression with significant modulation in xyloglucan endotrans hydrolase 5 (XTH5) and MYB2 expressions that correlated with the disease phenotypes. Electro‐mobility shift assay confirmed physical interaction of recombinant SaWRKY1 to SaXTH5 and SaMYB2 promoters. Comparative WRKY1 promoter analysis between resistant and susceptible plants revealed the presence of crucial motifs for defence mechanism exclusively in resistant accession. Additionally, many defence‐related genes displayed significant expression variations in both the accessions. Further, WRKY1 overexpressing transgenic plants exhibited higher levels of EB resistance while RNAi silencing lines had increased susceptibility to A. solani with altered expression of XTH5 and MYB2. Overall, these findings demonstrate the positive influence of WRKY1 in improving EB resistance in wild tomato and this could be further utilized as a potential target through genetic engineering to augment protection against A. solani in crop plants.
Gloriosa superba L. is a horticulturally and medicinally important plant. Its seeds have poor, erratic, and deferred germination. The detailed seed structure components and water imbibition mechanism facilitating the process of seed germination in G. superba remain unexplored. Therefore, it is essential to develop methods to ensure consistent and enhanced seed germination in G. superba. Various pre-sowing treatments along with the Brunauer-Emmett-Teller (BET) surface area analysis and 3D X-ray micro-tomography (micro-T) were employed to elucidate seed structure components, porosity network, and the water imbibition mechanism during germination in G. superba. The study revealed that consistent and significantly improved seed germination (>85%) was observed using the pre-sowing treatment mechanical scarification followed by 24 h water soaking in G. superba. BET and micro-T showed that the tegmen of the seed coat exhibited porosity (21%) with a well-connected porosity network (17.50%) that helped in water movement through hilum, which was confirmed by phosphotungstic acid staining. However, the sarcotesta and endosperm were water-impermeable due to their negligible porosity. Multidisciplinary techniques such as BET and micro-T along with conventional methodologies can be employed to address the seed coat structure, porosity, and water imbibition mechanism aiding seed germination. Mechanical scarification enabled the water to penetrate internal seed layers through the permeable tegmen via the reticulate pore network, which significantly improved seed germination. The developed seed germination method can produce a large number of plants in less time and conserve the natural populations of this high-value medicinally important species.