Hu Yuanyuan, Zhang Yongling, Yu Weiwu, Hänninen Heikki, Song Lili, Du Xuhua, Zhang Rui, Wu Jiasheng
State Key Laboratory of Subtropical Silviculture, Zhejiang A & F University, Hangzhou, China.
Key Laboratory of High Efficient Processing of Bamboo of Zhejiang Province, China National Bamboo Research Center, Hangzhou, China.
Front Plant Sci. 2018 Jan 9;8:2179. doi: 10.3389/fpls.2017.02179. eCollection 2017.
Seed oil content is an important trait of nut seeds, and it is affected by the import of carbon from photosynthetic sources. Although green leaves are the main photosynthetic organs, seed sarcotesta photosynthesis also supplies assimilates to seed development. Understanding the relationship between seed photosynthesis and seed development has theoretical and practical significance in the cultivation of cv. "Merrillii." To assess the role of seed sarcotesta photosynthesis on the seed development, anatomical and physiological traits of sarcotesta were measured during two growing seasons in the field. Compared with the attached current-year leaves, the sarcotesta had higher gross photosynthetic rate at the first stage of seed development. At the late second stage of seed development, sarcotesta showed down-regulation of PSII activity, as indicated by significant decrease in the following chlorophyll fluorescence parameters: the maximum PSII efficiency ( ), the PSII quantum yield (Φ ), and the photosynthetic quenching coefficient (). The ribulose 1, 5-bisphosphate carboxylase (Rubisco) activity, the total chlorophyll content (Chl) and nitrogen content in the sarcotesta were also significantly decreased during that period. Treatment with DCMU [3-(3,4-dichlorophenyl)-1,1-dimethylurea] preventing seed photosynthesis decreased the seed dry weight and the oil content by 25.4 and 25.5%, respectively. We conclude that seed photosynthesis plays an important role in the dry matter accumulation at the first growth stage. Our results also suggest that down-regulation of seed photosynthesis is a plant response to re-balance the source-sink ratio at the second growth stage. These results suggest that seed photosynthesis is important for biomass accumulation and oil synthesis of the seeds. The results will facilitate achieving higher yields and oil contents in nut trees by selection for higher seed photosynthesis cultivars.
种子油含量是坚果种子的一个重要性状，它受到光合源碳输入的影响。虽然绿叶是主要的光合器官，但种子外种皮光合作用也为种子发育提供同化物。了解种子光合作用与种子发育之间的关系在‘麦里尔’品种的栽培中具有理论和实践意义。为了评估种子外种皮光合作用在种子发育中的作用，在田间两个生长季节测量了外种皮的解剖学和生理学特性。与当年着生的叶片相比，在种子发育的第一阶段外种皮具有更高的总光合速率。在种子发育的第二阶段后期，外种皮显示出PSII活性下调，如下列叶绿素荧光参数显著下降所示：最大PSII效率（ ）、PSII量子产额（Φ ）和光合猝灭系数（ ）。在此期间，外种皮中的核酮糖1,5-二磷酸羧化酶（Rubisco）活性、总叶绿素含量（Chl）和氮含量也显著下降。用二氯苯基二甲基脲（DCMU）处理以阻止种子光合作用，分别使种子干重和油含量降低了25.4%和25.5%。我们得出结论，种子光合作用在第一个生长阶段的干物质积累中起重要作用。我们的结果还表明，种子光合作用的下调是植物在第二个生长阶段重新平衡源库比的一种反应。这些结果表明，种子光合作用对 种子的生物量积累和油脂合成很重要。这些结果将有助于通过选择具有较高种子光合作用的品种来提高坚果树的产量和油含量。
