Department of Horticulture, Zijingang Campus, Zhejiang University, Hangzhou 310058, PR China.
Hainan Institute, Zhejiang University, Sanya 572025, PR China.
J Exp Bot. 2023 Sep 29;74(18):5722-5735. doi: 10.1093/jxb/erad303.
Plant architecture imposes a large impact on crop yield. IDEAL PLANT ARCHITECTURE 1 (IPA1), which encodes a SQUAMOSA PROMOTER BINDING PROTEIN-LIKE (SPL) transcription factor, is a target of molecular design for improving grain yield. However, the roles of SPL transcription factors in regulating tomato (Solanum lycopersicum) plant architecture are unclear. Here, we show that the expression of SPL13 is down-regulated in the lateral buds of strigolactone (SL)-deficient ccd mutants and is induced by GR24 (a synthetic analog of SL). Knockout of SPL13 by CRISPR/Cas9 resulted in higher levels of cytokinins (CKs) and transcripts of the CK synthesis gene ISOPENTENYL TRANSFERASES 1 (IPT1) in the stem nodes, and more growth of lateral buds. GR24 suppresses CK synthesis and lateral bud growth in ccd mutants, but is not effective in spl13 mutants. On the other hand, silencing of the IPT1 gene inhibited bud growth of spl13 mutants. Interestingly, SL levels in root extracts and exudates are significantly increased in spl13 mutants. Molecular studies indicated that SPL13 directly represses the transcription of IPT1 and the SL synthesis genes CAROTENOID CLEAVAGE DIOXYGENASE 7 (CCD7) and MORE AXILLARY GROWTH 1 (MAX1). The results demonstrate that SPL13 acts downstream of SL to suppress lateral bud growth by inhibiting CK synthesis in tomato. Tuning the expression of SPL13 is a potential approach for decreasing the number of lateral shoots in tomato.
植物结构对作物产量有很大影响。理想植物结构 1（IPA1），它编码一个 SQUAMOSA PROMOTER BINDING PROTEIN-LIKE（SPL）转录因子，是提高谷物产量的分子设计目标。然而，SPL 转录因子在调节番茄（Solanum lycopersicum）植物结构中的作用尚不清楚。在这里，我们表明，在 Strigolactone（SL）缺乏的ccd 突变体的侧芽中，SPL13 的表达下调，并被 GR24（SL 的合成类似物）诱导。CRISPR/Cas9 敲除 SPL13 导致茎节点中的细胞分裂素（CK）水平和 CK 合成基因 ISOPENTENYL TRANSFERASES 1（IPT1）的转录物水平升高，并且侧芽生长更多。GR24 抑制 ccd 突变体中的 CK 合成和侧芽生长，但在 spl13 突变体中无效。另一方面，沉默 IPT1 基因抑制了 spl13 突变体的芽生长。有趣的是，在 spl13 突变体中，根提取物和分泌物中的 SL 水平显著增加。分子研究表明，SPL13 直接抑制 IPT1 和 SL 合成基因 CAROTENOID CLEAVAGE DIOXYGENASE 7（CCD7）和 MORE AXILLARY GROWTH 1（MAX1）的转录。结果表明，SPL13 通过抑制番茄中 CK 的合成，在 SL 下游作用以抑制侧芽生长。调节 SPL13 的表达是减少番茄侧枝数量的一种潜在方法。
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