**Signalling Crosstalk of Plant Defence Responses to Xylem-invading Pathogens**

Sabina Berne and Branka Javornik

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/61955

#### **Abstract**

[76] Amaro F, Ruotolo R, Martin-Gonzalez A, Faccini A, Ottonello S, Gutierrez JC. A pseudo-phytochelatin synthase in the ciliated protozoan Tetrahymena thermophila.

[77] Liu F, Kang SH, Lee Y-I, Choa Y-h, Mulchandani A, Myung NV, Chen W. Enzyme mediated synthesis of phytochelatin-capped CdS nanocrystals. Appl Phys Lett

[78] Kumar SA, Abyaneh MK, Gosavi SW, Kulkarni SK, Ahmad A, Khan MI. Sulfite re‐ ductase-mediated synthesis of gold nanoparticles capped with phytochelatin. Bio‐

[79] Zheng Y, Yang Z, Li Y, Ying JY. From glutathione capping to a crosslinked, phyto‐

[80] Krumov N, Perner-Nochta I, Oder S, Gotchev V, Angelov A, Posten C. Production of inorganic nanoparticles by microorganisms. Chem Eng Technol 2009;32:1026–35. [81] Morelli E, Cruz BH, Somovigo S, Scarano G. Speciation of cadmium - gamma-glu‐ tamyl peptides complexes in cells of the marine microalga Phaeodactylum tricornu‐

[82] Gioacchino Scarano EM. Properties of phytochelatin-coated CdS nanochrystallites

[83] Krumov N, Oder S, Perner-Nochta I, Angelov A, Posten C. Accumulation of CdS nanoparticles by yeasts in a fed-batch bioprocess. J Biotechnol 2007;132:481–86. [84] Nowack B, Brouwer C, Geertsma RE, Heugens EHW, Ross BL, Toufektsian M-C, Wijnhoven SWP, Aitken RJ. Analysis of the occupational, consumer and environ‐ mental exposure to engineered nanomaterials used in 10 technology sectors. Nano‐

[85] Krystofova O, Sochor J, Zitka O, Babula P, Kudrle V, Adam V, Kizek R. Effect of magnetic nanoparticles on tobacco BY-2 cell suspension culture. Int J Environ Res

formed in a marine phytoplanktonic alga. Plant Sci 2003;165: 803–10.

Compar Biochem Physiol C-Toxicol Pharmacol 2009;149:598–604.

chelatin-like coating of quantum dots. Adv Mater 2008;20:3410–5.

2010;97.

technol Appl Biochem 2007;47:191–5.

410 Abiotic and Biotic Stress in Plants - Recent Advances and Future Perspectives

tum. Plant Sci 2002;163:807–13.

toxicology 2013;7:1152–6.

Public Health 2013;10:47–71.

Xylem is a plant vascular tissue that transports water and dissolved minerals from the roots to the rest of the plant. It consists of specialized water-conducting tracheary ele‐ ments, supporting fibre cells and storage parenchyma cells. Certain plant pathogenic fun‐ gi, oomycetes and bacteria have evolved strategies to invade xylem vessels and cause highly destructive vascular wilt diseases that affect the crop production and forest eco‐ systems worldwide. In this chapter, we consider the molecular mechanisms of root-spe‐ cific defence responses against vascular wilt pathogens, with an emphasis on the most important and well-studied fungal (*Verticillium* spp. and *Fusarium oxysporum*) and bacteri‐ al (*Xanthomonas* spp. and *Ralstonia solanacearum*) pathogens. In particular, we present the current understanding of plant immune responses, from invasion perception to signal transduction and termination. Furthermore, we address the role of specific transcription factors involved in plant immunity and their regulatory network. We also highlight the crucial roles of phytohormones as signalling molecules in local and systemic defence re‐ sponses. Finally, we summarize the current knowledge of plant defence responses to xy‐ lem-invading pathogens to devise new strategies and methods for controlling these destructive plant pathogens.

**Keywords:** Vascular wilt pathogens, effectors, plant innate immunity, signal transduc‐ tion, biotic stress
