Aim To study the effects of multi-occurring stresses and the underlying mechanisms of cross-stress tolerance. Methods Wheat plants were exposed to moderate drought priming (the leaf water potential reached ca. -0.8 MPa) at the 5-6th leaf stage for 2 weeks, and the physiological and yield responses of the drought-primed and non-primed plants to low temperature stress (4/ 2°C in the day/ night for 2 days) at jointing stage were investigated. Results Under low temperature stress, the primed plants possessed higher leaf relative water content and much activated antioxidant system and hence reduced the oxidative injury to the photosynthetic apparatus, resulting in greater photosynthetic rate and higher grain yield as compared with the non-primed plants. In addition, increase of the ABA concentrations in leaf was found closely associated with the enhanced anti-oxidant enzymes activity in the primed plants.Conclusions Drought priming at vegetative stage improves cold tolerance of wheat at jointing stage via sustaining ROS homeostasis, during which ABA plays a key role in alleviating the effects of low temperature stress in the drought-primed plants.

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• Soil salinity severely affects and constrains crop production worldwide. Salinity causes osmotic and ionic stress, inhibiting gas exchange and photosynthesis, ultimately impairing plant growth and development. Arbuscular mycorrhiza (AM) have been shown to maintain light and carbon use efficiency under stress, possibly providing a tool to improve salinity tolerance of the host plants. Thus, it was hypothesized that AM will contribute to improved growth and yield under stress conditions. • Wheat plants (Triticum aestivum L.) were grown with (AMF+) or without (AMFÀ) arbuscular mycorrhizal fungi (AMF) inoculation. Plants were subjected to salinity stress (200 mM NaCl) either at pre-or post-anthesis or at both stages. Growth and yield components, leaf chlorophyll content as well as gas exchange parameters and AMF colonization were analysed. • AM plants exhibited a higher rate of net photosynthesis and stomatal conductance and lower intrinsic water use efficiency. Furthermore, AM wheat plants subjected to salinity stress at both pre-anthesis and post-anthesis maintained higher grain yield than non-AM salinity-stressed plants. • These results suggest that AMF inoculation mitigates the negative effects of salinity stress by influencing carbon use efficiency and maintaining higher grain yield under stress.

Molecular identification of fungal taxa commonly transmitted through seeds of sorghum in Western Africa is lacking. In the present study, farm-saved seeds, collected from four villages in Northern Burkina Faso, were surface sterilized and the distribution of fungal DNA in seeds and seven-day-old seedlings was analyzed by 18S ribosomal DNA (rDNA) amplicon sequencing. More than 99% of the fungal rDNA was found to originate from ascomycetes. The distribution of ascomycetes at species level was subsequently analyzed by barcoding of ITS2 rDNA. Eighteen Operational Taxonomic Units (OTUs) were identified from seedlings, compared to 29 OTUs from seeds. The top-eight most abundant ascomycete OTUs from seedlings were annotated as: Epicoccum sorghinum, Fusarium thapsinum, four different Curvularia spp., Exserohilum rostratum and Alternaria longissima. These OTUs were also present in amplicons from seed samples collected in Central Burkina Faso confirming a common occurrence. E. sorghinum was highly predominant in seedlings both measured by DNA analysis and by isolation. The dominance of E. sorghinum was particularly strong in roots from poorly growing seedlings. Pathogenicity of E. sorghinum isolates was compared to F. thapsinum by inoculation to seeds in vitro. Both fungal species caused significant inhibition of seedling growth (P<0.001) and Koch's postulates were fulfilled. Extensive, dark necrosis in roots was a typical symptom of E. sorghinum, whereas wilting of leaves was caused primarily by F. thapsinum. This study provides the first molecular approach to characterize the seedling mycoflora of sorghum in Western Africa and suggests E. sorghinum as a common root pathogen.