here - First Legume Society Conference (LSC1)

Book of Abstracts First Legume Society Conference 2013: A Legume Odyssey Novi Sad, Serbia, 9-11 May 2013
_________________________________________________________________________________________
Induced mutations in the TI1 gene encoding a major double-headed protease inhibitor in
Pisum sativum L. can reduce significantly the inhibition of target enzymes
Alfonso Clemente 1 , Maria del Carmen Arques 1 , Catherine Chinoy 2 , Marion Dalmais 3 , Christine le
Signor 4 , Abdel Bendahmane 3 , Claire Domoney 2
1
Estación Experimental del Zaidín (CSIC), Granada, Spain.
2
John Innes Centre, Norwich, U.K.
3
Unité de Recherche en Génomique Végétale, UMR INRA 1165 – CNRS 8114 - UEVE 2, Evry cedex,
France
4
UMR 1347 Agroécologie AgroSup/INRA/uB, Pôle Génétique & Ecophysiologie GEAPSI, Dijon cedex,
France
Trypsin / chymotrypsin inhibitors in the seeds of many legume crop species are regarded as antinutritional
proteins often leading to a requirement for heat-treatment of seed products prior to
their use in feed. A TILLING resource developed in Pisum sativum L. (pea) was exploited to
identify mutants in the major seed-expressed trypsin / chymotrypsin inhibitor gene, TI1, where
the inhibition of either or both of the target enzymes may be reduced. Three lines with missense
mutations in TI1, predicted to affect activity through alteration of (a) a conserved cysteine
residue, (b) the P1′ serine within the active site of the chymotrypsin inhibitory domain or (c)
overall charge of the carboxy-terminal domain involved in protein dimerization, were identified.
The mutants were back-crossed to the parent cultivar, Cameor, to generate mutant and wild type
segregant lines, where the effects of the mutations on overall activity, isoform charge and the
association properties of the encoded proteins could be examined and compared. The data show
that one mutation (C77Y) leads to a significant reduction in both trypsin and chymotrypsin
inhibitory activity, associated with the loss of activity of two TI1 isoforms. The second and third
classes of TI1 mutations showed lesser effects on overall inhibitory activity, despite their likely
impact on protein structure. The resource provides potential for providing novel germplasm with
improved properties for feed and food uses.
145