The Fungal Root Endophyte Serendipita indica (Piriformospora indica) Enhances Bread and Durum Wheat Performance under Boron Toxicity at Both Vegetative and Generative Stages of Development through Mechanisms Unrelated to Mineral Homeostasis.

While the importance of beneficial soil microorganisms for soil health and crop performance has been receiving ever-increasing attention, Serendipita indica has been widely studied as a fungal root endophyte with significant potential for increasing the stress tolerance of host plants. Boron (B) toxicity as an adverse soil condition is particularly prevalent in arid and semi-arid regions and threatens crop production. Studies on S. indica-wheat symbiosis are limited, and effects of S. indica on crops have never been reported in the context of B toxicity. Here, two pot experiments were conducted under greenhouse conditions to investigate the effects of S. indica on the growth and yield parameters of bread (Triticum aestivum) and durum wheat (Triticum durum) grown at different levels of B toxicity in native vs. sterilized soil, and parameters related to root colonization, membrane damage, oxidative stress, chlorophyll, and mineral nutrition were measured to elucidate the physiological mechanisms of damage and benefit. Boron toxicity decreased early vegetative growth and grain yield, but it did not affect the straw dry weight of mature plants, whereas S. indica significantly enhanced the vegetative growth, straw dry weight, and the grain number of both wheat species. Membrane damage as demonstrated by increased lipid peroxidation and relative electrolyte leakage was caused by B toxicity and alleviated by S. indica. The benefits provided by S. indica could not be attributed to any significant changes in tissue concentrations of B or other minerals such as phosphorus. Soil sterilization generally improved plant performance but it did not consistently strengthen or weaken the effects of S. indica. The presented results suggest that S. indica may be used as an effective microbial inoculant to enhance wheat growth under adverse soil conditions such as B toxicity through mechanisms that are possibly unrelated to mineral homeostasis.

DNA fingerprinting and assessment of some physiological changes in Al-induced Bryophyllum daigremontianum clones.

Aluminum (Al) is one of the most important stress factors that reduce plant productivity in acidic soils. Present work thereby analyzed Al-induced genomic alterations in Bryophyllum daigremontianum clones using RAPD and ISSR markers, and investigated responding changes in photosynthetic pigment (chlorophyll a, b, a/b, total chlorophyll and carotenoid) contents and total soluble protein amounts in plant leaves. The main reason for the use of bulbiferous spurs originated clone plants was to increase reliability and acceptability of RAPD and ISSR techniques in DNA fingerprinting. Raised 40 clone plants were divided into five separate groups each with eight individuals and each experimental group was watered with 0 (control), 0 (acid control), 50, 100 and 200 µM AlCl3-containing Hoagland solutions on alternate days for two and a half months. All plant soils except control group were sprayed with 0.2% sulfuric acid following watering days and this contributed acidic characteristic (pH 4.8) to soil structure. Increase in Al concentrations were accompanied by an increase in total soluble protein amounts, a decrease in photosynthetic pigment contents, and with appearance, disappearance and intensity changes at RAPD and ISSR band profiles. Out of tested RAPD1-25 and ISSR1-15 primers, RAPD8, RAPD9, ISSR2 and ISSR7 primers produced reproducible band profiles that were distinguishable between treatment and control groups. Findings showed that RAPD and ISSR fingerprints have been useful biomarkers for investigation of plant genotoxicity, especially in clone plants. Moreover, if these fingerprints are integrated with other physiological parameters they could become more powerful tools in ecotoxicology.