Kato Masahiro, Masamura Noriya, Shono Jinji, Okamoto Daisaku, Abe Tomoko, Imai Shinsuke
Basic Technology Development Division, Central Research &Development Institute, House Foods Group Inc., Yotsukaido, Chiba 284-0033, Japan.
Plant Breeding Institute Co., Ltd., Kuriyama-cho, Hokkaido 069-1511, Japan.
Sci Rep. 2016 Apr 6;6:23779. doi: 10.1038/srep23779.
The onion lachrymatory factor (LF) is produced from trans-S-1-propenyl-L-cysteine sulfoxide (PRENCSO) through successive reactions catalyzed by alliinase (EC 4.4.1.4) and lachrymatory factor synthase (LFS), and is responsible for the tear inducing-property and the pungency of fresh onions. We developed tearless, non-pungent onions non-transgenically by irradiating seeds with neon-ion at 20 Gy. The bulbs obtained from the irradiated seeds and their offspring bulbs produced by selfing were screened by organoleptic assessment of tear-inducing property or HPLC analysis of LF production. After repeated screening and seed production by selfing, two tearless, non-pungent bulbs were identified in the third generation (M3) bulbs. Twenty M4 bulbs obtained from each of them showed no tear-inducing property or pungency when evaluated by 20 sensory panelists. The LF production levels in these bulbs were approximately 7.5-fold lower than those of the normal onion. The low LF production levels were due to reduction in alliinase activity, which was a result of low alliinase mRNA expression (less than 1% of that in the normal onion) and consequent low amounts of the alliinase protein. These tearless, non-pungent onions should be welcomed by all who tear while chopping onions and those who work in facilities where fresh onions are processed.
洋葱催泪因子（LF）由反式-S-1-丙烯基-L-半胱氨酸亚砜（PRENCSO）经蒜氨酸酶（EC 4.4.1.4）和催泪因子合酶（LFS）催化的连续反应产生，它是新鲜洋葱产生催泪特性和刺激性的原因。我们通过用20 Gy的氖离子辐照种子，非转基因地培育出了无泪、无刺激性的洋葱。通过对催泪特性的感官评估或对LF产生的HPLC分析，对从辐照种子获得的鳞茎及其自交产生的后代鳞茎进行筛选。经过反复筛选和自交留种，在第三代（M3）鳞茎中鉴定出两个无泪、无刺激性的鳞茎。当由20名感官评价员进行评估时，从它们各自获得的20个M4鳞茎均未表现出催泪特性或刺激性。这些鳞茎中LF的产生水平比正常洋葱低约7.5倍。LF产生水平低是由于蒜氨酸酶活性降低，这是蒜氨酸酶mRNA表达水平低（不到正常洋葱的1%）以及随后蒜氨酸酶蛋白量低的结果。这些无泪、无刺激性的洋葱应该会受到所有在切洋葱时流泪的人和在新鲜洋葱加工场所工作的人的欢迎。
