Significance of light-induced hook exaggeration as reinforced by the concomitant anatomical change of germinating tomato seeds

Ethylene Is Not Responsible for Phytochrome-Mediated Apical Hook Exaggeration in Tomato

“…The photographs presented together in their papers show that the seedlings used there had already lost the seed coat and endosperm, and were at a more advanced stage than that of the seedlings used in our present study. At such an advanced stage we had previously noticed that no LIHE took place (Shichijo et al, 2010b; Shichijo and Hashimoto, 2013). Thus, the ethylene-induced hook exaggeration and LIHE are assumed to take place, respectively, at different developmental stages of dark-grown tomato seedlings.…”

“…Ponte-Rosa, Sekaiichi and Seikoh No.17, were purchased, respectively, from Ishihara Seed Co. (Sakai, Japan), Marutane Seed Co. (Kyoto, Japan) and Watanabe Seed Co. (Misatomachi, Miyagi, Japan). The three cultivars behaved similarly in phytochrome-mediated hook exaggeration (Shichijo et al, 2010a,b; Shichijo and Hashimoto, 2013), and were used arbitrarily in the present experiments. Seeds were sterilized for 10–20 min with 25-times diluted solution of commercial bleach, followed by thorough washing with running tap water for 30–90 min, and soaked in sterilized distilled water until full imbibition.…”

“…In tomato and some other dicotyledonous species characterized by seeds bearing the hard-to-split tough seed coat and the rich endosperm, the apical hook is markedly exaggerated by exposure to light, mediated by phytochromes through the very low, low and high irradiance responses, and hence activated by red (R) as well as far-red light (FR). The hook exaggeration and its subsequent opening motion facilitate the release of the seed coat, and contribute to the survival of the seedling above the ground (Shichijo et al, 2010a,b; Shichijo and Hashimoto, 2013). …”