Ideal Plant Architecture 1 (IPA1) encodes SQUAMOSA PROMOTER BINDING PROTEIN-LIKE 14 (SPL14) with a pleiotropic effect on regulating rice development and biotic stress responses. To investigate the role of IPA1 in early seedling development, we developed a pair of IPA1/ipal-NILs and found that seed germination and early seedling growth were retarded in the ipa1-NIL. Analysis of the soluble sugar content, activity of amylase, and expression of the α-amylase genes revealed that the starch metabolism was weakened in the ipa1-NIL germinating seeds. Additionally, the content of bioactive gibberellin (GA) was significantly lower than that in the IPA1-NIL seeds at 48 h of imbibition. Meanwhile, the expression of GA synthesis-related gene OsGA20ox1 was downregulated, whereas the expression of GA inactivation-related genes was upregulated in ipa1-NIL seeds. In addition, the expression of OsWRKY51 and OsWRKY71 was significantly upregulated in ipa1-NIL seeds. Using transient dual-luciferase and yeast one-hybrid assays, IPA1 was found to directly activate the expression of OsWRKY51 and OsWRKY71, which would interfere with the binding affinity of GA-induced transcription factor OsGAMYB to inhibit the expression of α-amylase genes. In summary, our results suggest that IPA1 negatively regulates seed germination and early seedling growth by interfering with starch metabolism via the GA and WRKY pathways.

中文翻译：

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IPA1 通过 GA 和 WRKY 途径干扰淀粉代谢，负调控早稻幼苗发育

Ideal Plant Architecture 1 (IPA1)编码 SQUAMOSA PROMOTER BINDING PROTEIN-LIKE 14 (SPL14)，对调节水稻发育和生物胁迫反应具有多效作用。为了研究的作用IPA1早期幼苗发育，我们制定了对IPA1 / IPAL -NILs，发现种子发芽和早期幼苗生长延缓了IPA1 -NIL。对可溶性糖含量、淀粉酶活性和α-淀粉酶基因表达的分析表明，ipa1- NIL 萌发种子的淀粉代谢减弱。此外，生物活性赤霉素（GA）的含量显着低于IPA1-NIL 种子在 48 小时的吸收。同时，在ipa1- NIL种子中GA合成相关基因OsGA20ox1的表达下调，而GA失活相关基因的表达上调。此外，OsWRKY51和OsWRKY71 的表达在ipa1 -NIL 种子中显着上调。使用瞬时双荧光素酶和酵母单杂交试验，发现 IPA1 直接激活OsWRKY51和OsWRKY71的表达，这会干扰 GA 诱导的转录因子 OsGAMYB 的结合亲和力，从而抑制α-淀粉酶基因的表达。总之，我们的结果表明IPA1通过 GA 和WRKY途径干扰淀粉代谢，对种子萌发和早期幼苗生长进行负调节。