8th INTERNATIONAL WHEAT CONFERENCE

PRoduCTIoN of WheAT hIgh AmyLoSe STARCheS
ThRough The kNoCkouT of SBeIIA geNeS
Sestili F., Botticella E., Janni M., Doherty A., Paoletti
F., Jones H., D’Ovidio R., Lafiandra D.
Department of Agrobiology and Agrochemistry, University of Tuscia, Via San Camillo de
Lellis snc, 01100 Viterbo, Italy
E-mail Address of presenting author: francescosestili@unitus.it
In the last twenty years the discovery and production of functional foods have opened
a new frontier for food industry due to their positive effect on health and wellbeing. In
this contest high amylose starch has attracted particular interest because of its correlation
with amount of Resistant Starch (RS) in food. RS plays a role similar to dietary fibre
with beneficial effects for human health, preventing against several diseases such as colon
cancer, diabetes, obesity, osteoporosis and cardiovascular illnesses. In this context the
production of high amylose wheat starch is particularly interesting because flour and
semolina are used for the production of different kind of foods such as bread, pasta, pizza,
cakes, snacks.
Reserve starch is accumulated in the amylopast organelles and composed of two glucan
polymers, amylose and amylopectin. They are synthesized by two different pathways, having
a common substrate (ADG-glucose). A sole enzyme (GBSSI or waxy) is responsible
for amylose biosynthesis; whereas several classes of enzymes are involved in amylopectin
synthesis such as starch syntheses (SSI, SSII, SSIII), branching (SBEI, SBEIIa and SBEIIb)
and debranching (isoamylase- and pullulanase-type) (ISA and LD) enzymes.
In this conference a biotechnological approach to produce high amylose starch is presented.
RNA interference was carried out to inactivate genes encoding SBEIIa enzymes
in two cultivars of durum wheat, using two different methods of transformation (biolistic
and Agrobacterium).
Amylose content was markedly increased in the durum wheat transgenic lines (the values
ranged from 30.8% up to 75%). The starch granules in these lines were deeply affected,
being smaller than those present in the untransformed controls; moreover the shape was
irregular and deflated. Two novel granule bound proteins were identified by SDS-PAGE
in transgenic lines and investigated by mass spectrometry. RVA analysis showed new
pasting properties associated to high amylose lines in comparison with untransformed
controls. Finally, pleiotropic effects on other starch genes were found by semiquantitative
and Real-Time reverse transcription-polymerase chain reaction (RT-PCR).
471