TY - JOUR TI - Application of bacteria from non-cultivated plant relatives to promote growth, alleviate stress, and alter gene expression of cotton DO - https://doi.org/doi:10.7282/T3SJ1PGP PY - 2017 AB - Beneficial bacterial endophytes are capable of promoting growth and alleviating abiotic and biotic stress in plants. This dissertation will present research that was undertaken to test the overarching hypothesis that non-cultivated relatives of crops in stressed environments possess beneficial bacteria capable of promoting growth and alleviating stress in cultivated plants. This hypothesis will be tested using cotton as a model and will seek bacteria in non-cultivated relatives in the Malvaceae family. Cultivated cotton provides a useful model for these studies because cotton seeds are acid delinted. Acid delinting is a century-old process that involves treating seeds with diluted sulfuric or hydrochloric acid to remove fuzzy lint covering seeds which facilitates cotton seed mass production and reduces the prevalence of seed-borne diseases. This practice likely disturbs the seed-transmitted cotton microbiome and thus, also affects the communities of beneficial microbes that are vertically transmitted to developing cotton seedlings. The research in this dissertation tested whether bacteria from non-cultivated, wild plants in the Malvaceae family in saline and arid areas in Puerto Rico promoted growth, alleviated salt stress, and protected cotton seedlings against seed-borne fungal diseases. Bacteria were isolated that enhanced cotton seed germination and altered the growth of various fungi. Among the bacteria isolated, Bacillus amyloliquefaciens was further demonstrated to promote growth, alleviate salt stress, and alter root architecture of cotton and okra seedlings. Using a GeneChip microarray gene expression analysis, it was demonstrated that inoculating cotton seedling roots with B. amyloliquefaciens led to the differential expression of hundreds of genes in both non-stressed and salt stressed conditions. Many of the differentially expressed genes could contribute to the phenotypic effects observed on inoculated cotton seedlings. Moreover, B. amyloliquefaciens inhibited growth of numerous fungi and produced lipopeptides with antifungal and chlamydospore-inducing properties. Data supported that B. amyloliquefaciens promoted growth and alleviated biotic and abiotic stress of multiple hosts making it a suitable candidate to be used as a biofertilizer and biocontrol agent. Biological agents that enhance plant growth and health have the potential to decrease the demand for nitrogenous fertilizers and fungicides which are costly and detrimental to the environment. KW - Plant Biology KW - Cotton--Genetics KW - Endophytes LA - eng ER -