Pivoting from Arabidopsis to wheat to understand how agricultural plants integrate responses to biotic stress

Abstract

In this review, we argue for a research initiative on wheat's responses to biotic stress. One goal is to begin a conversation between the disparate communities of plant pathology and entomology. Another is to understand how responses to a variety of agents of biotic stress are integrated in an important crop. We propose gene-for-gene interactions as the focus of the research initiative. On the parasite's side is an Avirulence (Avr) gene that encodes one of the many effector proteins the parasite applies to the plant to assist with colonization. On the plant's side is a Resistance (R) gene that mediates a surveillance system that detects the Avr protein directly or indirectly and triggers effector-triggered plant immunity. Even though arthropods are responsible for a significant proportion of plant biotic stress, they have not been integrated into important models of plant immunity that come from plant pathology. A roadblock has been the absence of molecular evidence for arthropod Avr effectors. Thirty years after this evidence was discovered in a plant pathogen, there is now evidence for arthropods with the cloning of the Hessian fly's vH13 Avr gene. After reviewing the two models of plant immunity, we discuss how arthropods could be incorporated. We end by showing features that make wheat an interesting system for plant immunity, including 479 resistance genes known from agriculture that target viruses, bacteria, fungi, nematodes, insects, and mites. It is not likely that humans will be subsisting on Arabidopsis in the year 2050. It is time to start understanding how agricultural plants integrate responses to biotic stress.

Leaf-mining by Phyllonorycter blancardella reprograms the host-leaf transcriptome to modulate phytohormones associated with nutrient mobilization and plant defense

“…Jasmonic acid (JA) and 66 salicylic acid (SA) have long been known as major plant hormones 67 involved in fine-tuning of plant defenses, although many complex 68 interactions also involve other hormones, such as abscisic acid 69 (ABA) and cytokinins (CKs) (Robert-Seilaniantz et al, 2011;Erb 70 et al, 2012). To circumvent this plant defense activation process, phytohormone analogs (Schultz, 2002;Schultz and Appel, 2004; 75 Kazan and Lyons, 2014;Harris et al, 2015;Guiguet and Dubreuil, 76 this issue; Zhao et al, this issue). 77 Phytohormones play important roles in regulating plant devel-78 opmental processes and signaling networks involved in plant 79 responses to a wide range of biotic and abiotic interactions (Bari 80 and Jones, 2009).…”

The Conformation of a Plasma Membrane-Localized Somatic Embryogenesis Receptor Kinase Complex Is Altered by a Potato Aphid-Derived Effector

“…However, their cognate R genes have not yet been cloned and the mechanism of recognition of these effectors is not known (Harris et al, 2015;Stuart, 2015). No aphid effector recognized by an R protein, including Mi-1.2, has yet been identified (Kaloshian and Walling, 2016).…”

Plants make galls to accommodate foreigners: some are friends, most are foes

“…New stem rust strains arising on the alternate host barberry are sometimes able to overcome Resistance genes deployed in wheat (Zhao et al , ). Fortunately, hundreds of Resistance genes have been discovered in wheat and its relatives, among which have been found genes effective against new stem rust strains (Singh et al , ; Dean et al , ; Harris et al , ; Lorrain et al , ). This is also the case for the Hessian fly, Mayetiola destructor , an insect pest of wheat that caused havoc when it invaded North America in the late eighteenth century (Harris et al , ).…”