Page 1 Page 2 Page 3 Page 4 Page 5 Page 6 Page 7 Page 8 Page 9 Page 10 Page 11 Page 12 Page 13 Page 14 Page 15 Page 16 Page 17 Page 18 Page 19 Page 20 Page 21 Page 22 Page 23 Page 24 Page 25 Page 26 Page 27 Page 28 Page 29 Page 30 Page 31 Page 32 Page 33 Page 34 Page 35 Page 36 Page 37 Page 38 Page 39 Page 40 Page 41 Page 42 Page 43 Page 44 Page 45 Page 46 Page 47 Page 48 Page 49 Page 50 Page 51 Page 52 Page 53 Page 54 Page 55 Page 56 Page 57 Page 58 Page 59 Page 60 Page 61 Page 62 Page 63 Page 64 Page 65 Page 66 Page 67 Page 68 Page 69 Page 70 Page 71 Page 72 Page 73 Page 74 Page 75 Page 76 Page 77 Page 78 Page 79 Page 80 Page 81 Page 82 Page 83 Page 84 Page 85 Page 86 Page 87 Page 88 Page 89 Page 90 Page 91 Page 92 Page 93 Page 94 Page 95 Page 96 Page 97 Page 98 Page 99 Page 100 Page 101 Page 102 Page 103 Page 104 Page 105 Page 106 Page 107 Page 108 Page 109 Page 110 Page 111 Page 112 Page 113 Page 114 Page 115 Page 116 Page 117 Page 118 Page 119 Page 120 Page 121 Page 122 Page 123 Page 124 Page 125 Page 126 Page 127 Page 128 Page 129 Page 130 Page 131 Page 132 Page 133 Page 134 Page 135 Page 136 Page 137 Page 138 Page 139 Page 140 Page 141 Page 142 Page 143 Page 144 Page 145 Page 146 Page 147 Page 148120 / SEEDWORLD.COM DECEMBER 2016 HER GREENHOUSE-GROWN soybean plants fix twice as much nitrogen from the atmosphere as their natural coun- terparts, grow larger and produce up to 36 percent more seeds. Mechthild Tegeder, a Washington State University biologist, designed a novel way to increase the flow of nitrogen from spe- cialized bacteria in soybean root nodules to the seed-producing organs. She and Amanda Carter, a biological sciences graduate student, found the increased rate of nitrogen transport kicked the plants into overdrive. “The biggest implication of our research is that by ramping up the natural nitrogen allocation process, we can increase the amount of food we produce,” Tegeder says. Unlike crops that rely on naturally occurring and artificially made nitrogen from the soil, legumes contain rhizobia bacte- rioids in their root nodules that have the unique capability of con- verting or “fixing” nitrogen gas from the atmosphere. For years, scientists have tried to increase the rate of nitrogen fixation in legumes by altering rhizobia bacterioid function or interactions that take place between the bacterioid and the root nodule cells. Tegeder took a different approach: She increased the number of proteins that help move nitrogen from the rhizobia bacteria to the plant’s leaves, seed-producing organs and other areas where it is needed. The additional transport proteins sped up the overall export of nitrogen from the root nodules. This initiated a feedback loop that caused the rhizobia to start fixing more atmospheric nitrogen, which the plant then used to produce more seeds. “They are bigger, grow faster and generally look better than natural soybean plants,” Tegeder says. “Some evidence we have suggests they might also be highly efficient under stressful con- ditions like drought.” Tegeder thinks her research can eventually be applied to varieties of legumes suited for a diverse array of climates. One major benefit of growing legumes is that they not only can use atmospheric nitrogen for their own growth but also leave residual nitrogen in the soil for subsequent crops. Hence, increasing nitrogen fixation could improve overall plant productivity for farmers who grow legumes in both indus- trial and developing countries while diminishing or eliminating the need for nitrogen fertilizers. SW Doubling Nitrogen Fixation in Soybeans A Washington State University plant scientist may have discovered how to accomplish double nitrogen fixation in soybeans. Will Ferguson