Biology subjects

Leso, M.

Publications and source records attributed to Leso, M..

4 recordsLinked to original sources

bioRxiv2024

A long-distance inhibitory system regulates haustoria numbers in parasitic plants

The ability of parasitic plants to withdraw nutrients from their hosts depends on the formation of an infective structure known as the haustorium. How parasites regulate their haustoria numbers is poorly understood, and here, we uncovered that existing haustoria in the facultative parasitic plants Phtheirospermum japonicum and Parentucellia viscosa suppressed the formation of new haustoria on distant roots. Using Phtheirospermum japonicum, we found that this effect depended on the formation of mature haustoria and could be induced through the application of external nutrients. To understand the molecular basis of this root plasticity, we analyzed hormone response and found that existing infections upregulated cytokinin responsive genes first at the haustoria and then more distantly in Phtheirospermum shoots. We observed that infections increased endogenous cytokinin levels in Phtheirospermum roots and shoots, and this increase appeared relevant since local treatments with exogenous cytokinins blocked the formation of both locally and distantly formed haustoria. In addition, local overexpression of a cytokinin degrading enzyme in Phtheirospermum prevented this systemic inter-haustoria repression and increased haustoria numbers locally. We propose that a long-distance signal produced by haustoria negatively regulates future haustoria, and in Phtheirospermum, such a signaling system is mediated by a local increase in cytokinin to regulate haustoria numbers and balance nutrient acquisition.

plant biology↗

bioRxiv2023

PME-mediated pectin modifications promote haustoria initiation and xylem bridge development in the parasitic plant Phtheirospermum japonicum

O_LIParasitic plants produce cell wall modifying enzymes that are thought to be important for efficient host infection. Here, we investigated the role of pectin methylesterases (PMEs) and their inhibitors (PMEIs) during haustorium development in the facultative parasitic plant Phtheirospermum japonicum infecting Arabidopsis thaliana. C_LIO_LIWe employed immunohistochemistry to characterise tissue-specific changes in pectin methylesterification during haustorium development. We found putative PME and PMEI genes in P. japonicum and used genetic and transcriptomic approaches to identify those involved in haustorium development. C_LIO_LIOur results show tissue-specific changes in pectin methylesterification during haustorium development. De-methylesterified pectin correlated with haustorial intrusive cells whereas highly methylated pectin correlated with vascular tissues. We also found that inhibition of PME activity delayed haustoria development and xylem connectivity. Several PjPME and PjPMEI genes increased expression specifically during haustorium development but such increases did not occur when haustorium initiation or xylem connections were blocked by chemical treatment. C_LIO_LIThis study describes the importance of pectin modifications in parasitic plants during host infection. Our results suggest a dynamic regulation of PMEs and PMEIs contributes to haustoria initiation and to the establishment of xylem connections between parasite and host. C_LI

plant biology↗

bioRxiv2021

High temperature perception in leaves promotes vascular regeneration in distant tissues

Cellular regeneration in response to wounding is fundamental to maintain tissue integrity. Various internal factors including hormones and developmental pathways affect wound healing but little is known about how external factors influence regeneration. To better understand how the environment affects regeneration, we investigated the effects of temperature using the horticulturally relevant process of plant grafting. We found that elevated temperatures accelerated vascular regeneration of Arabidopsis thaliana and tomato (Solanum lycopersicum) grafts. Leaves were critical for this effect since blocking auxin transport or mutating PHYTOCHROME INTERACTING FACTOR4 (PIF4) or YUCCA2/5/8/9 in the cotyledons abolished the temperature enhancement. However, these perturbations had no effect upon graft healing at ambient temperatures and mutations in PIF4 did not affect the temperature enhancement of callus formation or tissue adhesion, suggesting that leaf-derived auxin was specific for enhancing vascular regeneration in response to elevated temperatures. Tissue-specific perturbations of auxin response using a BODENLOS (BDL) mutant revealed an asymmetric effect of temperature upon regeneration: the presence of bdl above the cut prevented temperature enhancement whereas the presence of bdl below the cut prevented graft healing regardless of temperature. Promotion of tissue regeneration by elevated temperatures was not specific for graft healing and we found that elevated temperatures accelerated xylem formation between the parasite Phtheirospermum japonicum and host Arabidopsis thaliana, and this effect required shoot-derived auxin from the parasite. Taken together, our results identify a pathway by which elevated temperatures accelerate vascular development which could be of relevance for improving regeneration and better understanding inter-plant vascular connections.

plant biology↗

bioRxiv2021

Nitrates increase abscisic acid levels to regulate haustoria formation in the parasitic plant Phtheirospermum japonicum

Parasitic plants are globally prevalent pathogens that withdraw nutrients from their host plants using an organ known as the haustorium. Some, the obligate parasites are entirely dependent on their hosts for survival, whereas others, the facultative parasites, are independent of their hosts and infect depending on environmental conditions and the presence of the host. How parasitic plants regulate their haustoria in response to their environment is largely unknown. Using the facultative root parasite Phtheirospermum japonicum, we found that external nutrient levels modified haustorial numbers. This effect was independent of phosphate and potassium but nitrates were sufficient and necessary to block haustoria formation. Elevated nitrate levels prevented the activation of hundreds of genes associated with haustoria formation, downregulated genes associated with xylem development and increased levels of abscisic acid (ABA). Enhancing ABA levels independently of nitrates blocked haustoria formation whereas reducing ABA biosynthesis allowed haustoria to form in the presence of nitrates suggesting that nitrates mediated haustorial regulation in part via ABA production. Nitrates also inhibited haustoria formation and reduced infectivity of the obligate root parasite Striga hermonthica, suggesting a more widely conserved mechanism by which parasitic plants adapt their extent of parasitism according to nitrogen availability in the external environment.

plant biology↗