Molybdenum Nutrition of Alfalfa

Abstract

Molybdenum is the latest element to be found essential for microorganisms and higher plants. The literature, recently reviewed by MULDER (12), indicates that Mo is necessary for N fixation by Azotobacter and Rhizobium and for the metabolism of nitrates by all plants. The biological importance of Mo was originally discovered by BORTELS (3, 4), who reported that Azotobacter and peas, soybeans, and red clover showed increases in growth and in N fixation from additions of Mo. Essentiality of Mo for higher plants was first demonstrated by Arnon and Stout in 1939. Using highly purified nutrient solutions, they produced Mo-deficiency symptoms in tomatoes in six successive experiments. Later JENSEN and BETTY (9) and JENSEN (10) reported that small applications of Mo to alfalfa and clover growing in pots of sand increased the yields of tops and the N content of both tops and roots. Mulder showed that nodulated peas grown in culture solutions lacking both Mo and combined N quickly developed Ndeficiency symptoms. The Mo requirement of tomatoes was greatly reduced when ammonium N was substituted for nitrate N in the nutrient solutions. Recent work by HEWITT and JONES (8) indicates that Mo is indispensable for the growth of tomatoes, cauliflower, cabbage, and mustard and that it functions in the reduction of nitrates. VANSELOW and DATTA (15), using the spectrographic method, studied the Mo requirements of lemons and found that leaves containing 0.01 p.p.m. Mo were deficient but those containing concentrations greater than 0.024 p.p.m. were normal. Deficiency was produced with either nitrate or ammonia N.Further investigation of the importance of Mo in plant nutrition has been stimulated by reports of Mo-deficient soils in AUSTRALIA (1, 2),

Mechanism of Action of Micronutrient Elements in Enzyme Systems

“…With reference to other possible functions of molybdenum, Hewitt & Agar wala (63) report that a molybdenum deficiency in representative higher plants greatly depresses the reduction of triphenyltetrazolium by the tissues. This is in line with the results previously reported by Evans et al (43) that homogenates of molybdenum-deficient lucerne foliage had a decreased hydrogenase activity as measured by methylene blue reduction. The signifi cance of metal deficiency effect on enzyme activity such as reported above, is discussed in the section, "Metal Deficiencies and Enzyme Constitution."…”

Diphosphopyridine Nucleotide-Nitrate Reductase from Soybean Nodules.

“…Garner and Allard (3) have shown that short alternations of light and dark inhibit the growth of many plants. Arthur, Guthrie, and Newell (1) found that tomato plants were extremely sensitive to long day length and will not survive under continuous illumination. The leaf injury symptoms reported by these authors are similar to those observed here-small, stiff, yellow leaves with dark necrotic spots.…”

“…It is well established that molybdenum is necessary for the utilization of nitrates by legumes (1,6) and that an increased supply is required when leguminous plants are forced to utilize atmospheric nitrogen. Jensen (4) has reported that nodules from alfalfa contain 5 to 15 times higher concentrations of molybdenum than roots of plants.…”

Glyceraldehyde-3-Phosphate Ferredoxin Oxidoreductase fromMethanococcus maripaludis

“…The purified protein was subjected to metal content analysis using inductively coupled plasma-mass spectrometry ([ICP-MS] SPQ-9000 with SII nanotechnology) after wet-sample digestion by 5 ml of HNO 3 and 1 ml of HClO 4 (11). Controls were conducted using [2Fe-2S]-ferredoxin from spinach (Sigma) and bovine serum albumin (Sigma).…”