Symbiotic Status, Phosphate, and Sucrose Regulate the Expression of Two Plasma Membrane H+-ATPase Genes from the Mycorrhizal Fungus Glomus mosseae  

Abstract

The establishment of the arbuscular mycorrhizal symbiosis results in a modification of the gene expression pattern in both plant and fungus to accomplish the morphological and physiological changes necessary for the bidirectional transfer of nutrients between symbionts. H+-ATPase enzymes play a key role establishing the electrochemical gradient required for the transfer of nutrients across the plasma membrane in both fungi and plants. Molecular analysis of the genetic changes in arbuscular mycorrhizal fungi during symbiosis allowed us to isolate a fungal cDNA clone encoding a H+-ATPase, GmPMA1, from Glomus mosseae (BEG12). Despite the high conservation of the catalytic domain from H+-ATPases, detailed analyses showed that GmPMA1 was strongly related only to a previously identified G. mosseae ATPase gene, GmHA5, and not to the other four ATPase genes known from this fungus. A developmentally regulated expression pattern could be shown for both genes, GmPMA1 and GmHA5. GmPMA1 was highly expressed during asymbiotic development, and its expression did not change when entering into symbiosis, whereas the GmHA5 transcript was induced upon plant recognition at the appressorium stage. Both genes maintained high levels of expression during intraradical development, but their expression was reduced in the extraradical mycelium. Phosphate, a key nutrient to the symbiosis, also induced the expression of GmHA5 during asymbiotic growth, whereas sucrose had a negative effect. Our results indicate that different fungal H+-ATPases isoforms might be recruited at different developmental stages possibly responding to the different requirements of the life in symbiosis.

A Mycorrhizal-Specific Ammonium Transporter from Lotus japonicus Acquires Nitrogen Released by Arbuscular Mycorrhizal Fungi

“…We suggest that, together with the protons, which are actively transported into the interfacial apoplast by the plant and also by fungal H + -ATPases (Murphy et al, 1997;Gianinazzi-Pearson et al, 2000;Krajinski et al, 2002;Requena et al, 2003;Balestrini et al, 2007), the protons coming from the NH 4 + deprotonation process remain in the interface space and maintain or even reinforce the gradient for H + -dependent transport processes (Fig. 9).…”

Arbuscular mycorrhizal colonization in black poplar roots after defoliation by a non-native and a native insect

“…2b), while GmPMA1 transcripts were detected only in one replicate of the defoliated samples using one-step RT-PCR (data not shown), and not in RT-qPCR. Looking at the data previously reported by Requena et al (2003), GmHA5 showed a very low expression during non-symbiotic growth and a highly induced expression in mycorrhizal roots and in extra-radical hyphae. GmPMA1 was on the contrary more expressed in the pre-symbiosis and less in the late stages of symbiosis, in agreement with our results.…”

“…To verify the effect of defoliation on AM symbiosis functioning, the expression of fungal genes, for which a previous role during symbiosis was reported, has been evaluated (Requena et al 2003, Balestrini et al 2007, Cappellazzo et al 2008, Gomez-Ariza et al 2009). Due to their role in symbiosis, fungal and plant PT genes are considered as key genes for the symbiosis (Balestrini et al 2007, Bucher 2007.…”

“…GmPMA1 was on the contrary more expressed in the pre-symbiosis and less in the late stages of symbiosis, in agreement with our results. H + -ATPases play a role in the establishment of an electrochemical gradient, necessary for the transport of nutrients across the plasma membrane in both fungi and plants, but each isoform could be engaged at different developmental stages, probably in function of the different necessities in the symbiosis (Requena et al 2003).…”

Transcriptional snapshots provide insights into the molecular basis of arbuscular mycorrhiza in the model legume Medicago truncatula

“…In the well-studied 'Arum'-type interactions, the uptake of phosphorus and minerals occurs at the peri-arbuscular interface, which encompasses the fungal arbuscular membrane, the periarbuscular matrix, and the plant periarbuscular membrane (Gianinazzi-Pearson 1996;Harrison 1999;Parniske 2000). It has been shown that the uptake of phosphorus is energy-dependent, with plant and fungal plasma membrane H + -ATPases as well as a plant phosphate transporter being exclusively localised at the arbuscular interface Ferrol et al 2002;Harrison et al 2002;Requena et al 2003). In contrast to the nutrient uptake by the plant, intraradical hyphae are thought to be responsible for the translocation of carbohydrates to the fungus (Bago et al 2000;Graham and Miller 2005).…”