[Research advances in species diversity of arbuscular mycorrhizal fungi in terrestrial agro-ecosystem]. / é™†åœ°å†œä¸šç”Ÿæ€ç³»ç»Ÿä¸›æžèŒæ ¹çœŸèŒç‰©ç§å¤šæ ·æ€§ç ”ç©¶è¿›å±•.

Arbuscular mycorrhizal fungi (AMF) are ancient and ubiquitous soil microorganisms, which can form mutually beneficial association with most terrestrial plants. Within the symbiotic relationship, AMF helps their host plants to absorb nutrients such as nitrogen and phosphorus while obtains carbon from the hosts. AMF plays an important role in agricultural ecosystem, including promoting plant growth, improving crop quality, increasing plant stress resistance, stabilizing soil structure, keeping ecological balance, and maintaining a sustainable agricultural development. We summarized the research advances of AMF in terrestrial agro-ecosystem in recent years, by focusing on AMF species diversity, spatial and temporal distribution, and influence factors of AMF biodiversity in terrestrial agro-ecosystem of China. Further research works were also prospected.

Differences in the arbuscular mycorrhizal fungi-improved rice resistance to low temperature at two N levels: aspects of N and C metabolism on the plant side.

We performed an experiment to determine how N and C metabolism is involved in the low-temperature tolerance of mycorrhizal rice (Oryza sativa) at different N levels and examined the possible signaling molecules involved in the stress response of mycorrhizal rice. Pot cultures were performed, and mycorrhizal rice growth was evaluated based on treatments at two temperatures (15 °C and 25 °C) and two N levels (20 mg pot(-1) and 50 mg pot(-1)). The arbuscular mycorrhizal fungi (AMF) colonization of rice resulted in different responses of the plants to low and high N levels. The mycorrhizal rice with the low N supplementation had more positive feedback from the symbiotic AMF, as indicated by accelerated N and C metabolism of rice possibly involving jasmonic acid (JA) and the up-regulation of enzyme activities for N and C metabolism. Furthermore, the response of the mycorrhizal rice plants to low temperature was associated with P uptake and nitric oxide (NO).

[Effects of arbuscular mycorrhizal fungi on photosynthetic characteristics of maize under low temperature stress].

A pot experiment was conducted to study the effects of arbuscular mycorrhizal (AM) fungus Glomus etunicatum on the growth, relative chlorophyll content, chlorophyll fluorescence, and photosynthesis of maize (Zea mays L.) plants under low temperature (15 degrees C and 5 degrees C) stress. Low temperature decreased the AM root colonization. The shoot and root dry mass and the relative chlorophyll content of AM maize plants were higher than those of non-AM maize plants. AM maize plants had higher maximal fluorescence (F(m)), variable fluorescence (F(v)), maximum photochemical efficiency (F(v)/F(m)), and potential photochemical efficiency (F(v)/F(o)), and lower primary fluorescence (F(o)), compared with non-AM maize plants, and the differences were significant under 5 degrees C condition. The photosynthetic rate (P(n)) and transpiration rate (T(r)) of maize inoculated with G. etunicatum increased markedly. Under low temperature stress, the stomatal conductance (G(s)) of AM maize plants was significantly higher than that of non-AM maize plants, while the intercellular CO2 concentration (C(i)) of AM maize plants was notably lower than that of non-AM maize plants. It was suggested that AM fungi could alleviate the low temperature damage on maize plants via improving their leaf chlorophyll content, photosynthesis, and chlorophyll fluorescence, and enhance the low temperature tolerance of maize plants, resulting in the promotion of host plant growth and the increase of host plant biomass.

Arbuscular mycorrhizae reducing water loss in maize plants under low temperature stress.

Arbuscular mycorrhizal (AM) fungi form mutualistic mycorrhizal symbiotic associations with the roots of approximately 80% of all terrestrial plant species while facilitate the uptake of soil mineral nutrients by plants and in exchange obtain carbohydrates, thus representing a large sink for photosynthetically fixed carbon. Also, AM symbiosis increase plants resistance to abiotic stress such as chilling. In a recent study we reported that AM fungi improve low temperature stress in maize plants via alterations in host water status and photosynthesis. Here, the influence of AM fungus, Glomus etunicatum, on water loss rate and growth of maize plants was studied in pot culture under low temperature stress. The results indicated that low temperature stress significantly decreases the total fresh weight of maize plants, and AM symbiosis alleviate the water loss in leaves of maize plants.

[Advance of plant symbiosis receptor-like kinase in nonlegumes].

Most plants can form a symbiosis in root with microorganisms for mutual benefit, Nonlegumes mainly form the symbiotic mycorrhiza with arbuscular fungi. The interaction is initiated by invasion of arbuscular mycorrhizal (AM) fungi into the plant root, and follows by production of several special signal molecules, such as the symbiosis receptor-like kinase (SYMRK) from plant. SYMRK has an extracellular domain comprising three leucine-rich repeats (LRRs), a transmembrane domain and an cytoplasmic protein kinase domain. Symrk is required for a symbiotic signal transduction pathway from the perception of microbial signal molecules to the rapid symbiosis-related gene activation. Study of symrk may set up a solid foundation for giving further insight on the function and mechanism of plant-fungi symbiosis.