Growth and Photosynthetic Activity of Selected Spelt Varieties (Triticum aestivum ssp. spelta L.) Cultivated under Drought Conditions with Different Endophytic Core Microbiomes

Abstract

The role of the microbiome in the root zone is critically important for plants. However, the mechanism by which plants can adapt to environmental constraints, especially water deficit, has not been fully investigated to date, while the endophytic core microbiome of the roots of spelt (Triticum aestivum ssp. spelta L.) grown under drought conditions has received little attention. In this study, we hypothesize that differences in the endophytic core of spelt and common wheat root microbiomes can explain the variations in the growth and photosynthetic activity of those plants, especially under drought conditions. Our greenhouse experimental design was completely randomized in a 2 × 4 × 3 factorial scheme: two water regime levels (well-watered and drought), three spelt varieties (T. aestivum ssp. spelta L.: ‘Badenstern’, ‘Badenkrone’ and ‘Zollernspelz’ and one wheat variety: T. aestivum ssp. vulgare L: ‘Dakotana’) and three mycorrhizal levels (autoclaved soil inoculation with Rhizophagus irregularis, control (autoclaved soil) and natural inoculation (non-autoclaved soil—microorganisms from the field). During the imposed stress period, relative water content (RWC), leaf chlorophyll fluorescence, gas exchange and water use efficiency (WUE) were measured. Microscopic observations of the root surface through fungi isolation and identification were conducted. Our results indicate that ‘Badenstern’ was the most drought tolerant variety, followed by ‘Zollernspelz’ and ‘Badenkrone,’ while the common wheat variety ‘Dakotana’ was the most drought sensitive. Inoculation of ‘Badenstern’ with the mycorrhizal fungi R. irregularis contributed to better growth performance as evidenced by increased whole plant and stalk dry matter accumulation, as well as greater root length and volume. Inoculation of ‘Zollernspelz’ with arbuscular mycorrhizal fungi (AMF) enhanced the photochemical efficiency of Photosystem II and significantly improved root growth under drought conditions, which was confirmed by enhanced aboveground biomass, root dry weight and length. This study provides evidence that AMF have the potential to be beneficial for plant growth and dry matter accumulation in spelt varieties grown under drought conditions.

Environmental Stress and Plants

“…spelta L.) roots under drought conditions is poorly understood. Ratajczak et al [13] found that inoculating the tolerant 'Badenstern' variety with the mycorrhizal fungus R. irregularis contributed to improved growth performance. The inoculation of less tolerant varieties (such as "Zollernspelz") also produces positive effects on the roots under stress.…”

Analysis of Physiological Status in Response to Water Deficit of Spelt (Triticum aestivum ssp. spelta) Cultivars in Reference to Common Wheat (Triticum aestivum ssp. vulgare)

“…These mechanisms include gas exchange, chlorophyll fluorescence, relative water content, lipid peroxidation index, proline, and anthocyanins accumulation, and facilitate the development of different genetic approaches to improve plant drought resistance and prevention of yield loss in economically important wheat. In contrast to common wheat, only a few studies assessed the spelt wheat's resistance to water shortages [5][6][7][8]. The effect of drought stress on the physiological properties and the course of the photosynthesis process in spelt wheat have not been fully characterized and explained.…”

Environmental interference of plant−microbe interactions

“…A striking example of this are the major changes observed in root‐associated fungal communities in Triticum aestivum plants under drought stress (Salamon et al, 2020 ). Another study from the same group pointed into the same direction, highlighting that drought stress indirectly affected the plant−fungal interactions in roots of T. aestivum (subspecies vulgare and spelta ), while still promoting plant growth and several physiological parameters, including photosynthetic activity, electron transport rate and water use efficiency (Ratajczak et al, 2020 ).…”