Antarctic root endophytes improve physiological performance and yield in crops under salt stress by enhanced energy production and Na+ sequestration

Abstract

climatic change is pointed as one of the major challenges for global food security. Based on current models of climate change, reduction in precipitations and in turn, increase in the soil salinity will be a sharp constraint for crops productivity worldwide. In this context, root fungi appear as a new strategy to improve plant ecophysiological performance and crop yield under abiotic stress. In this study, we evaluated the impact of the two fungal endophytes Penicillium brevicompactum and P. chrysogenum isolated from Antarctic plants on nutrients and na + contents, net photosynthesis, water use efficiency, yield and survival in tomato and lettuce, facing salinity stress conditions. Inoculation of plant roots with fungal endophytes resulted in greater fresh and dry biomass production, and an enhanced survival rate under salt conditions. Inoculation of plants with the fungal endophytes was related with a higher up/down-regulation of ion homeostasis by enhanced expression of the NHX1 gene. The two endophytes diminished the effects of salt stress in tomato and lettuce, provoked a higher efficiency in photosynthetic energy production and an improved sequestration of na + in vacuoles is suggested by the upregulating of the expression of vacuolar NHX1 Na + /H + antiporters. Promoting plant-beneficial interactions with root symbionts appears to be an environmentally friendly strategy to mitigate the impact of climate change variables on crop production. The earth faces dramatic environmental changes caused by the living habits of an increasing human population 1-3 which has consequences on life quality. A combination of effects from man-made global climate change, land degradation and contamination may compromise food production, for instance. Although traditional breeding and biotechnology are likely to overcome part of these constraints by engineering plants matching the environment 4 , more ecological and friendly practices would be highly beneficial as means to reduce the use of agro-pesticides and/or to enhance the environmental tolerance in agroecosystems. In this context, microbial symbionts of plants appear a promising alternative for improving plant performance and maintaining, or even increasing, the yield of crops 5-11. Soil salinization as a result of inappropriate cultural practices and excessive agricultural use is a symptom of land degradation. It currently affects a vast territory of productive areas throughout the world 12-14. Additionally, agriculture expands to regions that are naturally affected by salinity. Therefore, plant resistance to salt, mainly to the sodium cation (Na +), is a desirable trait in cultivated plants. One mechanism of plant tolerance in glycophytic (i.e. salt susceptible) species consists of reducing the cytoplasmic sodium concentration by sequestering Na + in the vacuole via tonoplast Na + /H + antiporters 15,16. Apart from reducing sodium toxicity, increased ion

WITHDRAWN: Plant growth promoting Bipolaris sp. CSL-1 mitigate salinity stress in soybean via altering endogenous phytohormonal level, antioxidants and genes expression

“…Similarly, bene cial effect of isolate CSL-1 on soybean growth were observed in root/shoot length, and biomass (fresh/dry weight) (Fig 2; Table 1). The result is supported with the nding of [20][21][22] who reported that NaCl tolerant Penicillum brevicompactum, P. chrysogenum, and mycorrhizal fungi augment salinity stress and enhance plant growth attribute in tomato, lettuce and pepper. Chlorophyll content play a vital role in photosynthesis and indicate the relative plant tolerance to salinity stress to some extent [23].…”

Effects of fungal inoculation on the growth of Salicornia (Amaranthaceae) under different salinity conditions

“…In addition to biomass increase, and N and P concentrations, photosynthesis has been also shown to be improved in plants colonized by endophytes, particularly those growing under salt stress (Ghorbani et al 2018;Molina-Montenegro et al 2020). The actual mechanisms vary.…”

A Symbiotic Approach to Generating Stress Tolerant Crops

“…There are numerous reports describing the benefits of fungal endophytes on seed germination, seedling vigor, abiotic, and biotic stress tolerance, and increased biomass of crop plants [ 38 , 40 , 41 , 42 , 43 , 44 , 45 ]. Although there are comparatively few reports on endophytes improving crop production under field conditions [ 38 ], fungal endophytes have shown good field efficacy for enhancing yields, biological control, and improving yield quality [ 38 , 43 , 44 , 45 ]. Extensive field testing demonstrated that ThSM3a conferred tolerance to drought and temperature extremes in both a monocot (corn) and eudicot (cotton).…”