Gianinetti Alberto, Finocchiaro Franca, Maisenti Fabio, Kouongni Satsap Dailly, Morcia Caterina, Ghizzoni Roberta, Terzi Valeria
Council for Agricultural Research and Economics-Research Centre for Genomics and Bioinformatics, via S. Protaso 302, 29017 Fiorenzuola d'Arda (PC), Italy.
J Fungi (Basel). 2018 Jun 14;4(2):71. doi: 10.3390/jof4020071.
Seed persistence in the soil is threatened by microorganisms, but the seed coat helps protect the seed from them. Although modern rice ( L.) cultivars have a whitish caryopsis, some varieties have a red caryopsis coat, a trait typical of wild species. The red colour is due to the oxidation of proanthocyanidins, a class of flavonoids that is found in the outer layers of the seed in many species. We aimed to assess whether these natural compounds (proanthocyanidins and proanthocyanidin-derived pigment) have some protective effect against microbial attacks. Dehulled caryopses of white-grained and red-grained rice genotypes were employed to assay fungal infection. Specifically, three white-grained rice cultivars (Perla, Augusto, and Koral) and three red-grained rice varieties (Perla Rosso, Augusto Rosso, and Koral Rosso) were used. In a first test, the caryopses were infected with at 10 °C, and seedling growth was then assessed at 30 °C. In a second test, the degree of infection by the mycotoxigenic fungus was assayed by measuring the accumulation of T-2/HT-2 toxins in the caryopses. Infection was performed at 10 °C to prevent rice germination while allowing fungal growth. In both the tests, red caryopses showed reduced, or delayed, infection with respect to white ones. One black-grained cultivar (Venere) was assayed for the accumulation of T-2/HT-2 toxins as well, with results corresponding to those of the red-grained rice varieties. We argue that the red pigment accumulating in the caryopsis coat, and/or the proanthocyanidins associated with it, provides a protective barrier against challenging microorganisms.
种子在土壤中的持久性受到微生物的威胁，但种皮有助于保护种子免受微生物侵害。虽然现代水稻（L.）品种的颖果呈白色，但一些品种具有红色颖果外皮，这是野生种的典型特征。红色是由于原花青素的氧化，原花青素是一类在许多物种种子外层中发现的黄酮类化合物。我们旨在评估这些天然化合物（原花青素和原花青素衍生色素）是否对微生物攻击具有某种保护作用。使用白粒和红粒水稻基因型的去壳颖果来测定真菌感染情况。具体而言，使用了三个白粒水稻品种（Perla、Augusto和Koral）和三个红粒水稻品种（Perla Rosso、Augusto Rosso和Koral Rosso）。在第一个试验中，将颖果在10℃下感染，然后在30℃下评估幼苗生长情况。在第二个试验中，通过测量颖果中T-2/HT-2毒素的积累来测定产毒真菌的感染程度。在10℃下进行感染以防止水稻发芽，同时允许真菌生长。在这两个试验中，红颖果相对于白颖果显示出感染减少或延迟。还对一个黑粒品种（Venere）进行了T-2/HT-2毒素积累的测定，结果与红粒水稻品种的结果一致。我们认为，在颖果外皮中积累的红色色素和/或与之相关的原花青素提供了一个针对具有挑战性的微生物的保护屏障。
