Integration of the metabolome and transcriptome reveals the resistance mechanism to low nitrogen in wild soybean seedling roots

Crop and weed competition studies rarely determine how plant-to-plant interactions alter the structure and physiology of crop roots. Soybean has the ability to detect neighboring weeds and to alter growth patterns including the allocation of resources to root growth. In this study, we hypothesized that low red : far red light ratio (R : FR) reflected from aboveground vegetative tissue of neighboring weeds would alter soybean root morphology and reduce root biomass and nodule number. All experiments were conducted under controlled conditions in which resources of light, water, and nutrients were nonlimiting. Low R : FR reflected from aboveground neighboring weeds reduced soybean seedling root length, surface area, and volume, including the number of nodules per plant. An accumulation of H2O2, an increase in malondialdehyde (MDA) content, a reduction in flavonoid content, and a decrease in 1,1-diphenyl-2-picrylhydrazyl (DPPH)–radicle scavenging activity were observed. The reduction in flavonoid content was accompanied by a decrease in the transcription ofGmIFS andGmN93 and an increase in transcript levels of several antioxidant genes. These molecular and physiological changes may have a physiological cost to the soybean plant, which may limit the plant's ability to respond to subsequent abiotic and biotic stresses that will occur under field conditions.

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Combined acid rain and lanthanum pollution and its potential ecological risk for nitrogen assimilation in soybean seedling roots

Environmental Pollution ◽

10.1016/j.envpol.2017.08.037 ◽

2017 ◽

Vol 231 ◽

pp. 524-532 ◽

Cited By ~ 17

Author(s):

Fan Zhang ◽

Mengzhu Cheng ◽

Zhaoguo Sun ◽

Lihong Wang ◽

Qing Zhou ◽

...

Keyword(s):

Acid Rain ◽

Ecological Risk ◽

Nitrogen Assimilation ◽

Potential Ecological Risk ◽

Soybean Seedling ◽

Seedling Roots

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Oomycete Species Associated with Soybean Seedlings in North America—Part I: Identification and Pathogenicity Characterization

Phytopathology ◽

10.1094/phyto-04-16-0177-r ◽

2017 ◽

Vol 107 (3) ◽

pp. 280-292 ◽

Cited By ~ 47

Author(s):

J. Alejandro Rojas ◽

Janette L. Jacobs ◽

Stephanie Napieralski ◽

Behirda Karaj ◽

Carl A. Bradley ◽

...

Keyword(s):

United States ◽

North America ◽

The United States ◽

Limited Information ◽

Soybean Seedling ◽

Internal Transcribed Spacer Region ◽

Soybean Seedlings ◽

Phytophthora Spp ◽

Seedling Roots ◽

Production Areas

Oomycete pathogens are commonly associated with soybean root rot and have been estimated to reduce soybean yields in the United States by 1.5 million tons on an annual basis. Limited information exists regarding the frequency and diversity of oomycete species across the major soybean-producing regions in North America. A survey was conducted across 11 major soybean-producing states in the United States and the province of Ontario, Canada. In 2011, 2,378 oomycete cultures were isolated from soybean seedling roots on a semiselective medium (CMA-PARPB) and were identified by sequencing of the internal transcribed spacer region of rDNA. Sequence results distinguished a total of 51 Pythium spp., three Phytophthora spp., three Phytopythium spp., and one Aphanomyces sp. in 2011, with Pythium sylvaticum (16%) and P. oopapillum (13%) being the most prevalent. In 2012, the survey was repeated, but, due to drought conditions across the sampling area, fewer total isolates (n = 1,038) were collected. Additionally, in 2012, a second semiselective medium (V8-RPBH) was included, which increased the Phytophthora spp. isolated from 0.7 to 7% of the total isolates. In 2012, 54 Pythium spp., seven Phytophthora spp., six Phytopythium spp., and one Pythiogeton sp. were recovered, with P. sylvaticum (14%) and P. heterothallicum (12%) being recovered most frequently. Pathogenicity and virulence were evaluated with representative isolates of each of the 84 species on soybean cv. Sloan. A seed-rot assay identified 13 and 11 pathogenic species, respectively, at 13 and 20°C. A seedling-root assay conducted at 20°C identified 43 species as pathogenic, having a significantly detrimental effect on the seedling roots as compared with the noninoculated control. A total of 15 species were pathogenic in both the seed and seedling assays. This study provides a comprehensive characterization of oomycete species present in soybean seedling roots in the major production areas in the United States and Ontario, Canada and provides a basis for disease management and breeding programs.

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