Yongchao Yu, Xuemei Xu, Yuxiang Hu, Yanfeng Ding, Lin Chen
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引用次数: 0
Abstract
The yield potential of large-panicle rice is often limited by grain-filling barriers caused by the development of inferior spikelets (IS). Photoassimilates, which are the main source of rice grain filling, mainly enter the caryopsis through the dorsal vascular bundle. The distribution of assimilates between superior spikelets (SS) and IS is influenced by auxin-mediated apical dominance; however, the mechanism involved is still unclear. In this study, the effect of auxin signaling on the grain filling of SS and IS was investigated in two large-panicle japonica rice varieties, W1844 and CJ03. Compared to SS, IS displayed delayed initiation of filling and a significantly lower grain weight. Furthermore, the endosperm development in IS remained stagnant at the coenocytic stage. The development of the dorsal vascular bundle in the IS was also slow, and poor sucrose-unloading was observed during the initial grain filling stage. However, the endosperm development in IS immediately started after the improvement of dorsal vascular bundle development. GUS activity staining further revealed that indole-3-acetic (IAA) was localized in the dorsal vascular bundle and surrounding areas, suggesting that the low IAA content observed in the IS during the initial grain filling stage may have delayed the development of the dorsal vascular bundle. Therefore, these results demonstrate that IAA may control sugar transport and unloading by regulating dorsal vascular bundle development, consequently affecting endosperm development in IS.
大粒水稻的产量潜力往往受到下位小穗(IS)发育造成的谷粒充实障碍的限制。光同化物是水稻籽粒充实的主要来源,主要通过背维管束进入颖果。同化物在上部小穗(SS)和下部小穗(IS)之间的分布受辅助素介导的顶端优势的影响;然而,其中的机理仍不清楚。本研究调查了 W1844 和 CJ03 这两个大穗粳稻品种中辅助素信号对 SS 和 IS 谷粒灌浆的影响。与 SS 相比,IS 的籽粒灌浆开始时间延迟,粒重明显降低。此外,IS 的胚乳发育仍停留在同胚层阶段。IS 背维管束的发育也很缓慢,在谷粒灌浆初期蔗糖卸载能力很差。然而,在背维管束发育改善后,IS 的胚乳发育立即开始。GUS 活性染色进一步显示,吲哚-3-乙酸(IAA)定位于背维管束及其周围区域,这表明在谷粒灌浆初期 IS 中观察到的低 IAA 含量可能延迟了背维管束的发育。因此,这些结果表明,IAA 可能通过调节背维管束的发育来控制糖的运输和卸载,从而影响 IS 中胚乳的发育。
期刊介绍:
Rice aims to fill a glaring void in basic and applied plant science journal publishing. This journal is the world''s only high-quality serial publication for reporting current advances in rice genetics, structural and functional genomics, comparative genomics, molecular biology and physiology, molecular breeding and comparative biology. Rice welcomes review articles and original papers in all of the aforementioned areas and serves as the primary source of newly published information for researchers and students in rice and related research.