Deyou Ye has completed his PhD from College of Horticulture, Nanjing Agricultural University of China. He is the director of lab for Institute of Vegetables, Gansu Academy of Agricultural Sciences. He has published more than 20 papers in reputed journals of China. At present, he is engaged in the research on root-knot nematodes in vegetables.
Root-knot nematodes (Meloidogyne spp.) cause serious threat to cucumber production throughout the world. Cucumis metuliferus, a relative of cucumber, is reported to be resistant to Meloidogyne incognita. However, the underlying resistance mechanism remains unclear. Here the response of resistant C. metuliferus strain CmR07 following the nematode infection was studied in comparison with susceptible C. sativus cv. Jinlv No.3. Roots of selected Cucumis seedings were analysed using histological and biochemical techniques. Transcriptome changes of the resistant reaction were investigated by RNA-seq. Our present results showed that penetration and development of the nematode in resistant plant were reduced when compared to susceptible plant. Infection of resistant genotype with M. incognita resulted in a hypersensitive reaction. The induction of phenylalanine ammonia lyase and peroxidase activities after infection was greater in resistant roots compared with the susceptible one. Several most relevant genes from the phenylpropanoid biosynthesis, plant hormone signal transduction and plant-pathogen interaction pathway that are involved in resistance to the nematode were significantly altered. The resistance in CmR07 to M. incognita is associated with reduced nematode penetration, retardation of nematode development and hypersensitive necrosis. The expression of genes resulting in the deposition of lignin, toxic compounds synthesis, suppression of nematode feeding and resistance protein accumulation, and activation of several transcription factors, all which might contribute to the resistance response to the pest. These results would lead to a better understanding the resistance mechanism and aid in the identification of potential targets resistant to the pest for cucumber genetic improvement.rnrn
Wynston Woodenberg is a postdoctoral fellow at the University of KwaZulul-Natal, Durban, South Africa, who has over ten years’ experience with microscopy of gymnosperm seeds
Plant cell walls are dynamic in that they can change conformation during ontogeny and in response to various stresses. These changes have been characterised for vegetative tissues; however, even though seeds are the primary propagatory units in most plants, little is known about the conformational responses of zygotic embryo cell walls to desiccation, which is a common abiotic stress. This motivated the present study, which investigates the effect of drying on the gross morphology of the zygotic embryo cell walls of three gymnosperm species: Podocarpus henkelii, which produces desiccation-sensitive seeds; Pinus elliottii, the seeds of which are desiccation-tolerant; and Podocarpus falcatus, which produces seeds that appear to be intermediate. Cryo-scanning electron microscopy was used to observe the responses of embryo cell walls to desiccation. Hydrated embryos of all three species displayed polyhedral cells with relatively straight walls. Upon desiccation to c. 0.05 g g-1 (dry mass basis), cell walls assumed an undulated conformation, the severity of which appeared to be limited by the subcellular accumulation of carbohydrate-containing amyloplasts in P. henkelii, lipid bodies in P. falcatus, and protein and lipid in P. elliottii. Intercellular spaces between cortical cells were also observed to enlarge upon desiccation, suggesting that components and/or processes at these junctions may be affected by desiccation. When dried embryos were rehydrated, embryo cell walls of P. henkelii remained moderately undulated, while those of P. falcatus and P. elliottii returned to their original straight conformation. Cell-cell connectivity and hence, communication (via the plasmalemma) is dependent on cell wall conformation. The results obtained here suggest that seed desiccation sensitivity may in part be based on the inability of dried-rehydrated embryo cell walls, such as those of P. henkelii, to regain their original straight conformation which can compromise cell-cell communication needed for growth