Biology subjects

Molloy, B.

Publications and source records attributed to Molloy, B..

4 recordsLinked to original sources

bioRxiv2026

Antagonistic action of a nuclear hormone receptor pair coordinates a switch from lytic to biotrophic effector production in a plant-parasitic nematode

Pathogens secrete overlapping and sequential waves of effectors to manipulate their host, and yet the regulators that conduct the ensemble are poorly understood. Here, we identify the Dorsal Gland Regulator DGR-1 in the beet cyst nematode Heterodera schachtii. DGR-1 controls the expression of 131 putative effectors, acting as a dual-functional switch that "switches off" early stage effectors involved in plant invasion, and "switches on" later stage effectors associated with biotrophic establishment in the host. Interestingly, DGR-1 works antagonistically with the only other known transcriptional regulator of effectors in plant-parasitic nematodes, the Subventral Gland Regulator-1 (SUGR-1), to coordinate this apparent switch from lytic to biotrophic effector production. Together, DGR-1 and SUGR-1 control the expression of nearly one half of all H. schachtii early-stage effectors, and over one fifth of effectors of any kind. The requirement to activate lytic effector functions in the cortex, and biotrophic effector functions in the vascular cylinder, suggests that this transcription factor pair must differentially respond to signals from the host. Consistent with this, we find that diffusates from the roots of A. thaliana Casparian strip mutant myb36/sgn3, which are enriched in molecules ordinarily restricted to the vascular cylinder, upregulate dgr-1, but not sugr-1, compared to Col-0. Taken together, these data indicate that H. schachtii responds to compartmentalised host-derived signals to appropriately regulate spatiotemporal effector expression during infection. Given that misregulating DGR-1 results in delayed development of parasitic nematodes in Arabidopsis and Mustard, strategies which impair effector regulation as a whole may hold promise for crop protection against these agriculturally important pathogens.

pathology↗

bioRxiv2026

Better late than never: the impact of hatching time on Heterodera schachtii parasitism

Plant-parasitic nematodes are a diverse, polyphyletic group of plant pathogens which can infect most plant tissues and all major crops. Amongst the most damaging clades are the cyst nematodes, which can remain dormant in the soil for decades as infection-competent, developmentally arrested, second-stage juveniles in eggs. Hatching is stimulated by a variety of factors. However, the impact of hatching factor responsiveness on nematode morphology, physiology, gene expression, and infection biology has not been explored. We examined the impact of hatching time on the beet cyst nematode, Heterodera schachtii. We found that late hatchers invaded host roots and established feeding sites in greater numbers than early hatchers. We demonstrate variation in baseline parasitism gene expression and in responsiveness of genes to effectostimulins, small, plant-derived molecules which upregulate parasitism genes. Three quarters of effectostimulin-induced transcriptional changes were also modulated, either positively or negatively, by hatching time. While there were no observable morphological differences between early and late hatching nematodes on the day of their emergence from the egg, the late hatchers displayed signs of faster utilisation of internal energy reserves after 7 days at 4{degrees}C, as evidenced by less body area attributed to fat, than early hatchers. Finally, we found no evidence of substantive genetic differences between early and late hatchers, they were representative of a single population, despite the observed differences in infection, gene expression, and physiology. Taken together, non-genetic differences likely drive late hatchers to more rapidly utilise their internal energy reserves, to be more responsive to host-derived signals, and to be ultimately more infective than their early hatching counterparts.

molecular biology↗

bioRxiv2024

The SUbventral-Gland master Regulator (SUGR) of nematode virulence

All pathogens must tailor their gene expression to their environment. Therefore, targeting host:parasite biology that regulates these changes in gene expression could open up routes to pathogen control. Here, we show that in the plant-parasitic nematode Heterodera schachtii, host signals (termed effectostimulins) within plant roots activate the master regulator sugr1. SUGR1, then, directly binds effector promoters, and orchestrates their production. Effector production, in turn, facilitates host entry, releasing more effectostimulins. These data show that gene expression during the very earliest stages of parasitism is defined by a feed forward loop for host entry. Importantly, we demonstrate that blocking SUGR1 blocks parasitism, underlining the SUGR1 signalling cascade as a valuable target for crop protection. Given that nematodes also parasitise humans and other animals, the potential impact is broad: disrupting effector production could, in principle, be applied to any pathogen that secrets effectors. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=146 SRC="FIGDIR/small/576598v1_ufig1.gif" ALT="Figure 1"> View larger version (32K): org.highwire.dtl.DTLVardef@cebedaorg.highwire.dtl.DTLVardef@153fe87org.highwire.dtl.DTLVardef@16b6957org.highwire.dtl.DTLVardef@d0e920_HPS_FORMAT_FIGEXP M_FIG C_FIG

pathology↗

bioRxiv2024

The origin, deployment, and evolution of a plant-parasitic nematode effectorome

Plant-parasitic nematodes constrain global food security. During parasitism, they secrete effectors into the host plant from two types of pharyngeal gland cells. These effectors elicit profound changes in host biology to suppress immunity and establish a unique feeding organ from which the nematode draws nutrition. Despite the importance of effectors in nematode parasitism, there has been no comprehensive identification and characterisation of the effector repertoire of any plant-parasitic nematode. To address this, we advance techniques for gland cell isolation and transcriptional analysis to define a stringent annotation of putative effectors for the cyst nematode Heterodera schachtii at three key life-stages. We define 659 effector gene loci: 293 "known" high-confidence homologs of plant-parasitic nematode effectors, and 366 "novel" effectors with high gland cell expression. In doing so we define a comprehensive "effectorome" of a plant-parasitic nematode. Using this effector definition, we provide the first systems-level understanding of the origin, deployment and evolution of a plant-parasitic nematode effectorome. The robust identification of the comprehensive effector repertoire of a plant-parasitic nematode will underpin our understanding of nematode pathology, and hence, inform strategies for crop protection.

plant biology↗