**6. Conclusion**

**Figure 8.** Root hair promoting effect of DSP, A: Root of *Brassica rapa* grown in plant growth medium, B: root of *B. rapa*

A Comprehensive Survey of International Soybean Research - Genetics, Physiology, Agronomy and Nitrogen

The molecular mass of RHPP was analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) [6]. The molecular weight of the bioac‐ tive peptide was 1,198.2 Da (Figure 9), and the molecular weight of the amino acid sequence in KTI was searched. Positions 27–38 in KTI (Gly-Gly-Ile-Arg-Ala-Ala-Pro-Thr-Gly-Asn-Glu-Arg) were identical to this molecular weight, and this peptide was thus designated as the RHPP (Figure 9). The RHPP that was chemically synthesized was also shown to have root

**Figure 9.** Amino acid sequence of RHPP in Kunitz trypsin inhibitor, the RHPP amino acid sequence is shown by gray

Many other legumes form root-nodules with nitrogen fixing bacteria. The nitrogen fixing bacteria related to legume cultivation are classified into 13 genera (*Rhizobium*, *Ensifer*, *Meso‐ rhizobium*, *Bradyrhizobium*, *Methylobacterium*, *Azorhizobium*, *Devosia*, *Burkholderia*, *Phyllobacte‐*

Legumes such as *Astragalus sinicus*, *Trifolium repens*, and *Arachis hypogaea* are cultivated as green manure for the improvement of soil fertility. The host specificity of the nitrogen fixing bacteria, *M. huakuii*, *R. trifolii*, and *Bradyrhizobium* sp., are very high, infecting *A. sinicus*, *T.*

**5. Novel plant bioactive peptides from other legume**

*rium, Microvirga, Ochrobactrum, Cupriavidus,* and *Shinella*) and 98 species [31].

grown with DSP in plant growth medium. Bar denotes 1 mm.

hair promoting activity (data not shown).

box.

Relationships

56

Soybean supplies nitrogen into the soil environment by forming root nodules and accumu‐ lating protein in its seed. Soybean cultivation has been shown to enhance nitrogen circula‐ tion by about 3.6 times accompanied with increases in nitrogen fixing bacteria.

DSP has been shown to increase the fresh weight of plants, and a peptide from DSP promot‐ ed root hair formation in *B. rapa*. Moreover, other bioactive peptides were found by degra‐ dation of proteins from A. hypogaea with proteinaseK treatment. The proteins of legumes will also become nitrogen sources for plant growth and the soil environment.
