Effect on epidermal cell of soybean protein-degraded products and structural determination of the root hair promoting peptide

Abstract

Peptide(s) produced from degraded soybean protein by an alkaline protease from Bacillus circulans HA12 (degraded soybean-meal products; DSP) increased the number of both the root hair cells (trichoblasts) and hairless cells (atrichoblasts) of Brassica rapa by about 4.4 times and 1.9 times, respectively. To identify the root hair-promoting peptide(s) in DSP, the origin protein of the root hair-promoting peptide(s) was identified as Kunitz trypsin inhibitor (KTI). The root hair-promoting peptide in the degraded products of KTI was purified and produced a signal of 1,198.2 Da with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) analysis. A search of the amino acid sequence of KTI located the peptide GGIRAAPTGNER, which had a molecular weight identical to 1,198.2 Da. The peptide GGIRAAPTGNER was chemically synthesized, and the synthetic peptide possessed root hair-promoting activity. Thus, it is concluded that this peptide in DSP is the foreign bioactive peptide promoting the differentiation of root hairs.

Soybean Peptide: Novel Plant Growth Promoting Peptide from Soybean

“…Root hair promoting effect of degraded soybean meal products (DSP). A: root of Brassica rapa grown in plant growth medium (Matsumiya et al, 2007), B: root of B. rapa grown with DSP in plant growth medium. Bar denotes 1 mm.…”

“…Activates the synthesis of proteinase inhibitors (McGurl, et al, 1992) RHPP Root hair promotion Adventitious root formation GGIRAAPTGNER (Matsumiya et al, 2007) …”

“…Recently, utilization of organic fertilizers for the production of organic agricultural products is rising because healthcare and environmental concerns are increasing. Studies into utilization of soybean waste as a fertilizer and as bioactive materials have been attempted (Kubo et al, 1997;Matsumiya et al, 2007;Shinano et al, 1991;Yamazaki & Roppongi, 1998). This chapter describes utilization of soybean meal and the development of a bioactive peptide for plant growth.…”

Analysis of peptide uptake and location of root hair‐promoting peptide accumulation in plant roots

“…B. rapa and S. lycopersicum (Takii Seed Corp., Kyoto, Japan) were used for each assay. The soybean-meal medium contained 10% (w/v) soybean meal (Honen soyalex, Honen Corp., Tokyo, Japan) [21,22]; the Luria-Bertani medium contained 10 g peptone, 5 g yeast extract, 5 g NaCl, and 20 g agar (pH 7.0) in 1 l H 2 O [23]; and the plant growth medium contained a mixture of 1 ml trace nutrient solution (…”

“…An alkaline protease from Bacillus circulans HA12 efficiently degrades soybean meal, and subsequently, it was shown that a variety of peptides are produced by the degradation . The RHPP (Gly‐Gly‐Ile‐Arg‐Ala‐Ala‐Pro‐Thr‐Gly‐Asn‐Glu‐Arg) present in the degraded soybean‐meal products (DSP) has root hair‐promoting activity . The RHPP promotes root hair differentiation by increasing the number of trichoblasts (root hair cells) in Brassica rapa .…”