A bZIP transcription factor (CiFD) regulates drought- and low-temperature-induced flowering by alternative splicing in citrus
A bZIP transcription factor (CiFD) regulates drought- and low-temperature-induced flowering by alternative splicing in citrus
复制标题
bZIP 转录因子 (CiFD) 通过选择性剪接调节柑橘干旱和低温诱导的开花
DOI：
10.1111/jipb.13390
复制
发表时间：
2022-12-31
影响因子：
11.4
通讯作者：
Zhang，Jin-Zhi
中科院分区：
文献类型：
--
作者：
Ye，Li-Xia;Wu，Yan-Mei;Zhang，Jin-Zhi
干旱和低温是诱导成年柑橘开花的两个关键环境因素。然而，人们对潜在的监管机制知之甚少。 bZIP 转录因子 FD 是成花素激活复合物 (FAC) 的关键组成部分，该复合物由 FLOWERING LOCUS T (FT)、FD 和 14-3-3 蛋白组成。在本研究中，对柑橘中CiFD的分离和表征发现，CiFD存在选择性剪接（AS），形成两种不同的蛋白质（CiFDα和CiFDβ）。进一步研究发现，它们在柑橘不同组织中的表达模式相似，但亚细胞定位和转录活性不同。在烟草和柑橘中过量表达CiFDDNA序列(CiFD-DNA)、CiFDα或CiFDβ表现出提前开花,且CiFD-DNA转基因植株最早开花,其次是CiFDβ和CiFDα。有趣的是，CiFDα和CiFDβ分别是由低温和干旱诱导的。进一步分析表明，CiFDα可以与CiFT、Ci14-3-3形成FAC复合物，然后与柑橘APETALA1（CiAP1）启动子结合并促进其表达。然而，CiFDβ 可以独立于 CiFT 和 Ci14-3-3 直接与 CiAP1 启动子结合。这些结果表明，CiFDβ可以形成一条更直接、更简化的独立于FAC复合物的途径，通过AS调节干旱诱导的开花。此外，bHLH转录因子(CibHLH96)与CiFD启动子结合并促进CiFD在干旱条件下的表达。转基因分析发现CibHLH96可以促进转基因烟草开花。这些结果表明 CiFDis 通过不同的调控模式参与干旱和低温诱导的柑橘开花。
Drought and low temperature are two key environmental factors that induce adult citrus flowering. However, the underlying regulation mechanism is poorly understood. The bZIP transcription factor FD is a key component of the florigen activation complex (FAC) which is composed of FLOWERING LOCUS T (FT), FD, and 14‐3‐3 proteins. In this study, isolation and characterization ofCiFDin citrus found that there was alternative splicing (AS) ofCiFD, forming two different proteins (CiFDα and CiFDβ). Further investigation found that their expression patterns were similar in different tissues of citrus, but the subcellular localization and transcriptional activity were different. Overexpression of theCiFDDNA sequence (CiFD‐DNA),CiFDα, orCiFDβin tobacco and citrus showed early flowering, andCiFD‐DNA transgenic plants were the earliest, followed byCiFDβandCiFDα. Interestingly,CiFDαandCiFDβwere induced by low temperature and drought, respectively. Further analysis showed that CiFDα can form a FAC complex with CiFT, Ci14‐3‐3, and then bind to the citrusAPETALA1(CiAP1) promoter and promote its expression. However, CiFDβ can directly bind to theCiAP1promoter independently of CiFT and Ci14‐3‐3. These results showed that CiFDβ can form a more direct and simplified pathway that is independent of the FAC complex to regulate drought‐induced flowering through AS. In addition, a bHLH transcription factor (CibHLH96) binds toCiFDpromoter and promotes the expression ofCiFDunder drought condition. Transgenic analysis found thatCibHLH96can promote flowering in transgenic tobacco. These results suggest thatCiFDis involved in drought‐ and low‐temperature‐induced citrus flowering through different regulatory patterns.