title: Involvement of reactive oxygen species in endosperm cap weakening and embryo elongation growth during lettuce seed germination.
abstract: Endosperm cap (CAP) weakening and embryo elongation growth are prerequisites for the completion of lettuce seed germination. Although it has been proposed that the cell wall loosening underlying these processes results from an enzymatic mechanism, it is still unclear which enzymes are involved. Here it is shown that reactive oxygen species (ROS), which are non-enzymatic factors, may be involved in the two processes. In Guasihong lettuce seeds imbibed in water, O2·(-) and H2O2 accumulated and peroxidase activity increased in the CAP, whereas its puncture force decreased. In addition, in the radicle, the increase in embryo growth potential was accompanied by accumulation of O2·(-) and an increase in peroxidase activity. Imbibing seeds in 0.3% sodium dichloroisocyanurate (SDIC) reduced endosperm viability and the levels of O2·(-), H2O2, and peroxidase activity in the CAP, whereas the decrease in its puncture force was inhibited. However, in the embryo, SDIC did not affect the accumulation of O2·(-), peroxidase activity, and the embryo growth potential. As a result, SDIC caused atypical germination, in which the endosperm ruptured at the boundary between the CAP and lateral endosperm. ROS scavengers and ROS generation inhibitors inhibited the CAP weakening and also decreased the embryo growth potential, thus decreasing the percentage of seed germination. Exogenous ROS and ROS generation inducers increased the percentage of CAP rupture to some extent, and the addition of H2O2 to 0.3% SDIC enabled some seeds to undergo typical germination.
authors.affiliation: Seed Science and Technology Lab, College of Life Sciences, South China Agricultural University, Guangzhou 510642, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Seed Science and Technology Lab, College of Life Sciences, South China Agricultural University, Guangzhou 510642, China.
authors.forename: Bingxian
authors.initials: B
authors.lastname: Chen
authors.affiliation: Seed Science and Technology Lab, College of Life Sciences, South China Agricultural University, Guangzhou 510642, China.
authors.forename: Zhenjiang
authors.initials: Z
authors.lastname: Xu
authors.affiliation: Seed Science and Technology Lab, College of Life Sciences, South China Agricultural University, Guangzhou 510642, China.
authors.forename: Zhaowan
authors.initials: Z
authors.lastname: Shi
authors.affiliation: Seed Science and Technology Lab, College of Life Sciences, South China Agricultural University, Guangzhou 510642, China.
authors.forename: Shanli
authors.initials: S
authors.lastname: Chen
authors.affiliation: Seed Science and Technology Lab, College of Life Sciences, South China Agricultural University, Guangzhou 510642, China.
authors.forename: Xi
authors.initials: X
authors.lastname: Huang
authors.affiliation: Seed Science and Technology Lab, College of Life Sciences, South China Agricultural University, Guangzhou 510642, China.
authors.forename: Jianxun
authors.initials: J
authors.lastname: Chen
authors.affiliation: Seed Science and Technology Lab, College of Life Sciences, South China Agricultural University, Guangzhou 510642, China xfwang@scau.edu.cn.
authors.forename: Xiaofeng
authors.initials: X
authors.lastname: Wang
mesh_terms: D056625:Endosperm / Q000201:enzymology / Q000254:growth & development* / Q000378:metabolism; D018525:Germination / Q000502:physiology*; D018545:Lactuca / Q000201:enzymology / Q000254:growth & development* / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism*; D036226:Seedlings / Q000201:enzymology / Q000254:growth & development* / Q000378:metabolism; D012639:Seeds / Q000254:growth & development*; D014227:Triazines / Q000008:administration & dosage / Q000494:pharmacology; D014867:Water / Q000378:metabolism
chemical_list: D017382:Reactive Oxygen Species; D014227:Triazines; D014867:Water; C011765:troclosene
keywords: Embryo elongation growth; endosperm cap weakening; hydrogen peroxide; lettuce; peroxidase; puncture force; reactive oxygen species; seed germination; sodium dichloroisocyanurate; superoxide radicals.
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