Biology subjects

Kokla, A.

Publications and source records attributed to Kokla, A..

2 recordsLinked to original sources

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

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↗