Creation of novel barley germplasm usingan <italic>Epichloë</italic> endophyte

Abstract

Plant-endophyte associations play important roles in grassland agricultural ecology. Many studies indicate that endophytic fungi can promote host growth and reduce the biotic and abiotic stresses of host plants. Epichloe endophytes of the family Clavicitaceae are fungal symbionts of Pooideae grasses. These endophytes usually do not express any obvious host symptoms. Many Epichloe endophytes can endow hosts with increased abiotic stress tolerance as a result of enhanced growth, tillering, reproduction and nutrient acquisition, particularly under conditions of drought, cold, salt and nutrient deficiencies and thus, have important roles in pastoral agricultural systems. Animal-safe grass-endophyte associations that confer bio-protective properties for increased pasture persistence and productivity have been developed and commercialized. Artificial inoculation with symbiotic Epichloe microbes is an important technique for the creation of novel germplasm. Selected Epichloe strains can add value to some grass-based forage systems by providing both biotic and abiotic stress resistance. In addition, they can improve and strengthen grass physiological functions and plant vigor. The Epichloe bromicola WBE1 endophyte of Hordeum brevisubulatum played an important role in maintaining the growth of host grass by promoting nutrient absorption and maintaining the ionic balance under salt stress. E. bromicola WBE1 can produce peramine, an alkaloid produced by Epichloe species, that protects host grasses from herbivorous insects. However, this strain was unable to synthesize the alkaloids that are toxic to livestock, such as ergine, ergonovine, ergovaline or lolitrem B. Barley ( Hordeum vulgare ) is one of the most important cereal crops. The importance of barley to human and animal nutrition, and indeed to the foundation and maintenance of human civilization, is well documented. Traditional barley breeding for improved environmental stress tolerance has resulted in good varieties. However, conventional breeding techniques neglect the microorganisms in plants. In this study, animal-safe endophytic E. bromicola WBE1 isolated from wild barley ( H. brevisubulatum ) was artificially inoculated into cultivated hulled barley ( H. vulgare cv. Yangsimai No. 1) and hull-less barley ( H. vulgare var. nudum cv. Chaiqing No. 1), creating novel barley germplasm. Plants that were inoculated with endophytes and those that were free of endophytes were evaluated for growth in the field. The plant height, tiller numbers, biomass and the grain weight per plant of endophyte-inoculated hulled barley plants (Yangsimai No. 1) were 5%, 20%, 46% and 22% higher than those of the control hulled barley plants, respectively, and they matured about 5 days earlier. The tiller numbers, biomass and grain weight per plant of endophyte-inoculated hull-less barley plants (Chaiqing No. 1) were 29%, 37% and 28% higher, respectively, than those of the control hull-less barley plants in the field. However, there was no significant difference between inoculated hull-less barley plants and control hull-less barley plants in the plant height and growth period. A novel germplasm of barley containing the endophyte was successfully created. E. bromicola improves plant characteristics and the growth of host. The results presented here provide evidence that the inoculation of barley with E. bromicola may be used to improve its germplasm. E. bromicola can be successfully inoculated into other phylogenetically close host species, and this technique has the potential to improve the growth of Hordeae cereal crops and serve as a broad application to produce agriculturally useful synthetic novel symbioses in germplasm.