Seed endosymbiosis: a vital relationship in providing prenatal care to plants

Abstract

Global food security is a challenge, especially under changing climatic conditions. Recent advances in plant technology using plant-microbiome interactions promise an increased crop production. Indeed, all healthy plants or crop genotypes carry a beneficial microbiome, encompassing root-and seed-associated endosymbionts, providing mycotrophy and mycovitality to plants, respectively. Recent studies have found that mycovitality, or the endosymbiotic seed-fungus relationship and its key translational functions, bear tangible biotechnological benefits. Thus, this paper underlines the role of endophytes as early plant growth promoters under stressful environments. Notably, it explores the concept of plant prenatal care towards enhanced seed vigor, germination, and resilience, which results in an improved crop yield under stressful conditions. It presents an extensive research overview of endosymbiotic plant-fungi relationships with special focus on the wheat seed, an important source of staple food. Historical advances in terminology and scientific concepts on the subject are also presented to highlight the areas where further research is urgently needed.Key words: seed, plant microbiome, endophytes, fungi, plant prenatal care, climate change.Résumé : La sécurité alimentaire mondiale est un véritable enjeu, surtout face au changement climatique. Des progrès récents en technologie végétale reposant sur les réactions entre la plante et le microbiome promettent une hausse de la production. De fait, les plantes et les génotypes agricoles vigoureux possèdent tous un microbiome utile composé des endosymbiontes des racines et de la semence permettant au végétal de profiter respectivement des matières organiques décomposées par les champignons (mycotrophie) et de la mycovitalité. Des études récentes montrent que la mycovitalité, c'est-à-dire l'endosymbiose entre la graine et le champignon et ses principales fonctions traductionnelles, a des effets biotechnologiques tangibles et bénéfiques. Le présent article met en relief le rôle des endophytes en tant qu'accélérateur de croissance initial, quand les conditions sont difficiles. Plus précisément, il examine le concept des « soins prénataux » végétaux assurant une augmentation de la vigueur, la germination et la résilience des semences, qui aboutissent elles-mêmes à un rendement supérieur de la culture malgré les facteurs de stress. L'auteur offre un vaste survol de la recherche sur les liens endosymbiotiques entre la plante et les cryptogames, s'attardant notamment au blé, cette denrée capitale. Il se penche aussi sur l'évolution historique de la terminologie et des concepts scientifiques, pour faire ressortir les éléments sur lesquels il faudrait rapidement approfondir les recherches. [Traduit par la Rédaction]

Legume endosymbionts: Drought stress tolerance in second‐generation chickpea (Cicer arietinum) seeds

“…The crops may be affected by drought at any stage of the life cycle; however, certain stages including germination and seedling growth are critical for plant establishment, acclimation and performance ( Pessarakli, ). Specifically, the germination stage provides the basis for healthy plant development and continuous growth throughout phenophases (Vujanovic & Germida, ). In this study, chickpea was exposed to drought artificially created by PEG‐decreased water availability and IOP‐PDA‐ increased mechanical impedance and root penetration resistance to imitate soil drought conditions.…”

“…Endophytes used in this chickpea's study were previously tested on wheat demonstrating capacity to moderate hydrothermal time linked to seed germination and resilience to heat and drought via mycovitality (Hubbard et al., ; Vujanovic & Vujanovic, ) thus providing prenatal care to plant (Vujanovic & Germida, ). Under drought stress conditions chickpea (CDC Vanguard), seed germination was enhanced by fungal SMCD 2206, SMCD 2210 and bacterial SMCD 2215 endophytes.…”

“…Drought limits water availability in plants, and ultimately seed germination, growth and productivity of crops (Kaya, Okçub, Ataka, Çıkılıc, & Kolsarıcıa, ; Vujanovic & Germida, ). In drought conditions, reactive oxygen species (ROS) such as singlet oxygen, hydrogen peroxide, hydroxyl radicals and superoxides are produced, usually impact proper plant functioning (Sharma, Bhushan, Shanker, & Pessarakli, ; Sharma & Dubey, ).…”

“…As a result, the impact of microbial endophytes on plant adaptation at a molecular level can be better understood by assessing the expression of targeted stress‐related antioxidant genes under changing environments. Recently, the beneficial role of fungal endophytes has been linked to the plant immune system and inheritance of drought tolerance traits in plant hosts (Vujanovic & Germida, ). Specifically, it was suggested that some epigenetic changes at the molecular level might be the reason for increased stress tolerance in F2 wheat plants (Hubbard, Germida, & Vujanovic, ).…”

“…As a result, the impact of microbial endophytes on plant adaptation at a molecular level can be better understood by assessing the expression of targeted stress-related antioxidant genes under changing environments. Recently, the beneficial role of fungal endophytes has been linked to the plant immune system and inheritance of drought tolerance traits in plant hosts (Vujanovic & Germida, 2017).…”