Investigating Host and Parasitic Plant Interaction by Tissue-Specific Gene Analyses on Tomato and Cuscuta campestris Interface at Three Haustorial Developmental Stages

Abstract

Parasitic weeds cause billions of dollars in agricultural losses each year worldwide. Cuscuta campestris (C. campestris), one of the most widespread and destructive parasitic plants in the United States, severely reduces yield in tomato plants. Reducing the spread of parasitic weeds requires understanding the interaction between parasites and hosts. Several studies have identified factors needed for parasitic plant germination and haustorium induction, and genes involved in host defense responses. However, knowledge of the mechanisms underlying the interactions between host and parasitic plants, specifically at the interface between the two organisms, is relatively limited. A detailed investigation of the crosstalk between the host and parasite at the tissue-specific level would enable development of effective parasite control strategies. To focus on the haustorial interface, we used laser-capture microdissection (LCM) with RNA-seq on early, intermediate and mature haustorial stages. In addition, the tomato host tissue that immediately surround the haustoria was collected to obtain tissue- resolution RNA-Seq profiles for C. campestris and tomato at the parasitism interface. After conducting RNA-Seq analysis and constructing gene coexpression networks (GCNs), we identified CcHB7, CcPMEI, and CcERF1 as putative key regulators involved in C. campestris haustorium organogenesis, and three potential regulators, SlPR1, SlCuRe1-like, and SlNLR, in tomatoes that are involved in perceiving signals from the parasite. We used host-induced gene silencing (HIGS) transgenic tomatoes to knock-down the candidate genes in C. campestris and produced CRISPR transgenic tomatoes to knock out candidate genes in tomatoes. The interactions of C. campestris with these transgenic lines were tested and compared with that in wild-type tomatoes. The results of this study reveal the tissue-resolution gene regulatory mechanisms at the parasitic plant-host interface and provide the potential of developing a parasite-resistant system in tomatoes.

Transcriptional Basis for Haustorium Formation and Host Establishment in Hemiparasitic Psittacanthus schiedeanus Mistletoes

“…In root parasites of Orobanchaceae ( Triphysaria versicolor , Striga hermonthica , and Phelipanche aegyptiaca ), molecular evidence indicates that they evolutionarily recruited many genes for haustorial development and host penetration from genes that were involved in other processes in related non-parasitic plants, primarily root ( Sun et al, 2018 ) or flower development, but with some genes co-opted from other tissues ( Yang et al, 2015 ; Yoshida et al, 2016 ). These putative parasitism genes are also upregulated in the haustoria of Cuscuta campestris ( Ranjan et al, 2014 ), and auxin-mediated regulation of haustorium initiation shared by both root and stem parasitic plants ( Yoshida et al, 2016 ; Jhu et al, 2021 , 2022 ), would support the hypothesis that stem parasites also co-opted the root parasite program into haustorium development. Based on this, some authors proposed that haustoria might be interpreted as morphological misfits ( Rutishauser and Isler, 2001 ; Teixeira-Costa, 2021a ).…”

Regulatory Modules Involved in the Degradation and Modification of Host Cell Walls During Cuscuta campestris Invasion

“…Haustorial invasion is also facilitated by mechanical action and by biochemical degradation and modification of host cell walls ( Nagar et al, 1984 ; Olsen et al, 2016 ; Hozumi et al, 2017 ). Many genes encoding cell wall degrading and modifying enzymes were upregulated haustorium ( Ranjan et al, 2014 ; Ikeue et al, 2015 ; Jhu et al, 2022 ). Furthermore, the dynamics of cell wall components were observed by the penetration of haustorium into the host tissue ( Johnsen et al, 2015 ; Hozumi et al, 2017 ).…”

“…Since stable gene knockout approaches for Cuscuta plants is currently not available, it has not been possible to access in vivo function of CcERF52A and CcERF52B. However, it has recently been reported that the host-derived siRNAs could successfully down-regulate target gene transcription in C. campestris, via a host-induced gene silencing (HIGS) system ( Jhu et al, 2022 ). One of the challenges is the use of HIGS system for knockdown of CcERF52A and CcERF52B in C. campestri s. Further investigation of the relationship between CcERF52s and the cell wall enzyme genes will be needed to support our hypothesis.…”

“…For example, Jhu et al (2021) demonstrated that CcLBD25 is a crucial regulator of C. campestris haustorium development including haustorium initiation. Furthermore, three genes ( CcHB7, CcPMEI , and CcERF1 ) were recently identified as putative key regulators of C. campestris haustorium organogenesis ( Jhu et al, 2022 ). Previously, we also observed that C. campestris utilizes host-produced ethylene for the proper growth of search hyphae, and penetration into the host tissue is facilitated by the degradation and modification of host cell walls ( Narukawa et al, 2021 ; Yokoyama et al, 2021 ).…”

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“…Haustorial invasion is also facilitated by mechanical action and by biochemical degradation and modification of host cell walls (Nagar et al, 1984;Olsen et al, 2016;Hozumi et al, 2017). Many genes encoding cell wall degrading and modifying enzymes were upregulated haustorium (Ranjan et al, 2014;Ikeue et al, 2015;Jhu et al, 2022). Furthermore, the dynamics of cell wall components were observed by the penetration of haustorium into the host tissue (Johnsen et al, 2015;Hozumi et al, 2017).…”