Effects of inhibiting starch branching enzymes on molecular and crystalline structures of starches from endosperm different regions in rice.

Mature endosperm was separated regionally into different parts in three rice cultivars, Te-qing (TQ), Wu-xiang 9915 (WX9915) and Guang-ling-xiang-nuo (GLXN), and their transgenic lines with inhibition of starch branching enzyme I and IIb (SBEI/IIb-). Within the three wild-type cultivars, starches from endosperm different regions showed similar molecular and crystalline structures. However, in rices with inhibition of SBEs, amylopectin short branch-chain content and branching degree gradually decreased, but amylopectin B3+ chain content and average chain length increased gradually from the interior to exterior of endosperm. The amylose content gradually increased from the interior to exterior of endosperm in TQ- and WX9915-SBEI/II- lines. From the interior to exterior of endosperm, starch changed gradually from CC- to CB-type in TQ-SBEI/II- line and from CA- to CC-type in GLXN-SBEI/II- line, and remained CA-type in WX9915-SBEI/II- line. These results provided some information for quality breeding and utilizations of rice with inhibition of SBE.