Curtobacterium plantarum sp. nov. Is Ubiquitous in Plant Leaves and Is Seed Transmitted in Soybean and Corn 

Abstract

A total of 22 strains of a yellow-pigmented bacterium which I designated YB, which were isolated from leaves of various plants, were compared with the type strains of Curtobacterium citreum, Curtobacterium albidum, Curtobacterium luteum, and Curtobacterium pusillum and six strains of Curtobacterium jlaccumfaciens, a pathogen of soybeans and garden beans. These species comprise the genus Curtobacterium. YB was nonpathogenic when it was inoculated onto leaves of soybeans and garden beans and produced p-carotene, as did both C. citreum and C . luteum. These species and YB were all originally isolated from plants. YB could be distinguished from all previously described species of the genus Curtobacterium on the basis of more rapid production of acid from maltose and xylose, more rapid hydrolysis of gelatin, susceptibility to bacteriophage PYB-3 infection, inability to hydrolyze hippurate, growth in the presence of 10% sodium chloride, and higher deoxyribonucleic acid guanine-plus-cytosine content. Because the YB strains represent a new center of variation in the genus Curtobacterium, a new species, Curtobacterium plantarum, is proposed. This bacterium was isolated from leaves of three soybean cultivars at weekly intervals. Mean populations, expressed in colony-forming units (CFU) per gram of leaf tissue, increased gradually over the season from 28 CFU/g at 5 weeks after planting to 158 CFU/g at plant maturity. The bacterium was also isolated from leaves of 10 soybean cultivars and 10 corn inbred lines in each of 3 years, from leaves in one soybean field and one corn field in each of 25 Iowa counties, and from leaves of each of 100 soybean plants from one field and 100 corn plants from one field. Over a 2-year period, it was isolated from all 200 plant species sampled. The samples represented 62 plant families and included trees (both broad leaved, and conifers), shrubs, annuals, and perennials. The bacterium was isolated from field-grown immature and mature soybean seeds and from leaves of soybean and corn seedlings grown in a microbe-free environment from seeds treated to eliminate external microorganisms. I concluded that C. plantarum sp. nov. is seed transmitted in soybeans and corn and is ubiquitous in the leaves of plants.From 1881, when T. J. Burrill first established that Erwinia amylovora (Burrill) Winslow, Broadhurst, Buchanan, Krumwiede, Rogers and Smith is the cause of fire blight of apples and pears, the following two groups of plant-associated bacteria have been recognized: the pathogens, which invade plant tissues and produce disease, and the saprophytes, which utilize leaf and root surfaces as substrates but cause no disease. While isolating Curtobacterium Jlaccumfaciens pv. Jaccumfaciens (Hedges) Collins and Jones, which is pathogenic for leaves of soybeans (GIycine max [L.] Merr.) and garden beans (Phaseolus vulgaris L.), I consistently observed colonies of another yellow-pigmented bacterium that I designated YB (yellow-pigmented bacterium). YB was associated with other plants, such as corn, oats, a...

Isolation and characterization of endophytic bacteria from wild and traditionally cultivated rice varieties

“…Curtobacterium sp. inoculated to plants inhibited Erwinia-induced bacterial disease (Sturz and Matheson 1996), promoted plant growth (Sturz et al 1997), and occurred as seed-transmitted bacteria (Dunleavy 1989). Therefore, it is assumed that the Curtobacterium isolates may display these functions in rice and propagate themselves via rice seeds.…”

Bacterial Community Dynamics

“…Further, when some of the much-needed taxonomic studies on phyllosphere bacteria are published, they do not always clarify earlier studies on phylloplane communities. For example, are the "coryneform bacteria" isolated from perennial rye in England (Austin et al, 1978) the same as those isolated from maize (Zea mays) and soybean (Glycine max) in Iowa, which have been assigned to a new spedes, Curtobacterium plantarum (Dunleavy, 1989)?…”

Biological control of septoria leaf blotch and growth promotion in wheat by Paenibacillus sp. strain B2 and Curtobacterium plantarum strain EDS

“…Some Curtobacterium strains have been isolated from wheat, rice, corn, soybean, oats, alfalfa, olive and many other plants. C. plantarum, in particular, is seed transmitted (Dunleavy, 1989;Feng et al, 2017;Samain et al, 2015). The dual functions of C. plantarum in stimulating plant growth and degrading pollutants have been reported (Feng et al, 2017).…”