Identification molecular cloning and characterization of secretory proteins from wheat leaf rust fungus puccinia triticina

Abstract

Wheat is one of the highly consumed and produced crops in almost all parts of the world. However, the production of agricultural resources is not growing at a comparable pace moreover affected by infection caused by various plants such as wheat leaf rust pathogen Puccinia triticina. P. triticina are obligate biotrophic pathogens having special infecting structures called haustoria, which enable it to contact the hosts and secrete many virulence proteins. The analysis identified a novel rust effector protein Pt5643 containing ML domain involved in the host immune system manipulate. Further study showed that Pt5643 belong to NPC2 like proteins, a subfamily of ML domain superfamily, further suggesting NPC2 proteins were not only restricted to animals and insect species but also present in plant fungal pathogens, including members of Clavicipitaceae, Pucciniacease, and Tremellaceae family. The phylogenetic analysis showed that these NPC2 like fungal proteins are more closely related to animals/insects than other fungal species. The mRNA abundance of Pt5643 was observed to be increased along with the infection progression and exhibits the highest expression at 5thday post-infection (dpi), suggesting its important role in the P. triticina infection cycle in wheat.The fluorescent confocal microscopy of transiently expressed YFP tagged Pt5643 in onion epidermal cells and N. benthamiana shows its location near the plasma membrane and nucleus, indicating its membrane-associated functions and involvement in the manipulation of host genes. The functional complementation of Pt5643 in npc2 mutant yeast showed its functional similarity to the eukaryotic npc2 gene. Further, the overexpression of Pt5643 also suppressed the BAX and H2O2 induced program cell death in N. benthamiana and yeast, respectively thus proving to be a novel horizontally transferred effector in rust fungal pathogens.