Lathyrus sativus originating from different geographical regions reveal striking differences in Kunitz and Bowman-Birk inhibitor activities

Authors: XU, QUANLE - Northwest A&f University; QU, JINMIAO - Northwest A&f University; SONG, BO - Northeast Agricultural University, China; LIU, FENGJUAN - Northwest A&f University; CHEN, PENG - Northwest A&f University; Krishnan, Hari

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/2/2019
Publication Date: 7/24/2019
Citation: Xu, Q., Qu, J., Song, B., Liu, F., Chen, P., Krishnan, H.B. 2019. Lathyrus sativus originating from different geographical regions reveal striking differences in Kunitz and Bowman-Birk inhibitor activities. Journal of Agricultural and Food Chemistry. 67:8119-8129. https://doi.org/10.1021/acs.jafc.9b02604.
DOI: https://doi.org/10.1021/acs.jafc.9b02604

Interpretive Summary: Grass pea is an important legume due to its high protein content and good tolerance to harsh environmental conditions. On account of these characteristics, grass pea is often grown in drought-prone areas. Like soybean, grass pea seeds are relatively rich in protein and can serve as a highly nutritious, inexpensive, and well-balanced source of human dietary protein. However, both soybean and grass pea contain prominent protease inhibitors that are anti-nutritional factors. These protease inhibitors affect protein digestibility and hence lowering or eliminating anti-nutritional factors has been an important target for plant breeders. In this study, we have conducted biochemical characterization of 51 grass pea accessions originating from different geographical regions. Our study revealed striking differences in the activity of these protease inhibitors among these grass pea accessions. Grass pea accessions with low levels of protease activity identified in this study can be exploited by plant breeders to develop legumes that are devoid of anti-nutritional factors. Superior quality legume proteins can be utilized to meet the nutritional requirements of the multitude of malnourished people around the world.

Technical Abstract: Grass pea (Lathyrus sativus L.) is an important legume commonly grown in arid and semi-arid regions. This protein-rich legume performs well even under harsh environmental conditions and is considered to be a strategic famine food in developing countries. Unfortunately, its potential usage is greatly limited as a result of the presence of antinutritional factors, including the neuroexcitatory amino acid ß-N-oxalyl-l-a,ß-diaminopropionic acid (ß-ODAP) and protease inhibitors. ß-ODAP is responsible for a neurodegenerative syndrome that results in the paralysis of lower limbs, while protease inhibitors affect protein digestibility, resulting in reduced growth. Concerted research efforts have led to development of grass pea cultivars with reduced ß-ODAP content. In contrast, very little information is available on the protease inhibitors of L. sativus. In this study, we have conducted biochemical characterization of 51 L. sativus accessions originating from different geographical regions. Sodium dodecyl sulfate polyacrylamide gel electrophoresis analyses of seed globulins and prolamins revealed striking similarity in their protein profile, although geographic-specific variations in profiles was also evident. Measurement of Bowman–Birk chymotrypsin inhibitor (BBi) and Kunitz trypsin inhibitor (KTi) activities in accessions revealed striking differences among them. Amino acid sequence alignment of grass pea BBi and KTi revealed significant homology to protease inhibitors from several legumes. Real-time polymerase chain reaction analysis demonstrated high-level expression of BBi and KTi in dry seeds and weak expression in other organs. Our study demonstrates substantial variation in BBi and KTi among grass pea accessions that could be exploited in breeding programs for the development of grass pea lines that are devoid of these antinutritional factors.