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ARS Home » Midwest Area » Urbana, Illinois » Soybean/maize Germplasm, Pathology, and Genetics Research » Research » Publications at this Location » Publication #93112
Title: ANALYSIS OF LEGHEMOGLOBIN COMPONENTS AND XYLEM SAP COMPOSITION BY CAPILLARY ELECTROPHORESIS IN HYPERNODULATING MUTANTS OF SOYBEAN CULTIVATED IN THE FIELD

Author
item SATO, TAKASHI - NIIGATA UNIV, JAPAN
item YASHIMA, HIROYUKI - NIIGATA UNIV, JAPAN
item OHTAKE, NORIKUNI - NIIGATA UNIV, JAPAN
item SUEYOSHI, KUNI - NIIGATA UNIV, JAPAN
item AKAO, SHOICHIRO - AG RES, TSUKUBA, JAPAN
item Harper, James
item OHYAMA, TAKUJI - NIIGATA UNIV, JAPAN

Submitted to: Journal of Plant Nutrition and Soil Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/19/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary: Soybean nodulation involves a beneficial relationship between a soil bacteria and the soybean root to form a structure on the root (termed a nodule) which has capability of converting atmospheric nitrogen to ammonia which the plant can then use for growth and protein synthesis. This process is termed symbiotic nitrogen fixation and has important agricultural implications in terms a minimizing need for fertilizer nitrogen application. Soybean lines have been selected which have greater nodulation capability than typical cultivars. This study was conducted to determine if the specific compound (leghemoglobin) needed to translocate oxygen within the nodule was responsible for the difference in nodulation capability of the selected lines. The results indicated that leghemoglobin is not sufficiently different in the selected lines to account for the difference in nodulation capacity. It was confirmed that nitrogenous compounds derived from symbiotic nitrogen fixation were elevated in the selected lines, supporting the concept that these lines have greater symbiotic fixation capability. However, the biochemical pathways responsible for this greater nodulation capacity in soybean remain the be elucidated and are the subject of ongoing investigations.

Technical Abstract: The hypernodulation soybean mutant lines (NOD1-3, NOD2-4, NOD3-7) and their parent Williams, and the mutant En6500 and its parent Enrei, were cultivated in a sandy dune field in Niigata, and the nodules and root bleeding xylem sap were sampled at 50, 70, 90 and 120 days after planting (DAP). The nodule size distribution patterns and concentration of leghemoglobin components were determined. The hypernodulation mutant lines had about two to three times higher number of nodules than the parent lines irrespective of sampling date. At 50 DAP the nodule size was relatively smaller in hypernodulation mutant lines, and the total dry weight of nodules was almost the same between mutant lines and their parents. At 70 and 90 DAP, the size distribution of hypernodulation mutant nodules became almost the same as parent lines, and both the number and total dry weight of nodules were higher than the parent lines. The concentration of four Lb components was separately measured by capillary electrophoresis. The concentration of Lb components in hypernodulation mutant lines tended to be lower than in the parents, but the component ratios were not different between hypernodulation mutants and their parents. Under the field condition, the plant growth and nodulation characteristics were more similar between mutants and parents, compared with the hydroponic culture reported previously, although the mutants did exhibit hypernodulation traits. The concentration of major nitrogenous compounds (allantoic acid, allantoin, asparagine, aspartic acid and nitrate) in xylem sap was also measured by capillary electrophoresis. The concentration of ureides and nitrate in xylem sap decreased with plant age, but the asparagine concentration increased during the same period.