Key Laboratory of Horticultural Plant Growth, Development and Biotechnology, Agricultural Ministry of China, Department of Horticulture, Zhejiang University, Hangzhou, 310085, China.
Boyce Thompson Institute, Cornell University, Ithaca, NY, 14853, USA.
BMC Genomics. 2017 Nov 2;18(1):843. doi: 10.1186/s12864-017-4238-9.
Autogamy in cultivated tomato varieties is a derived trait from wild type tomato plants, which are mostly allogamous. However, environmental stresses can cause morphological defects in tomato flowers and hinder autogamy. Under elevated temperatures, tomato plants usually exhibit the phenotype of stigma exsertion, with severely hindered self-pollination and fruit setting, whereas the inherent mechanism of stigma exsertion have been hitherto unknown. Numerous small RNAs (sRNAs) have been shown to play significant roles in plant development and stress responses, however, none of them have been studied with respect to stamen and pistil development under high-temperature conditions. We investigated the associations between stigma exsertion and small RNAs using high-throughput sequencing technology and molecular biology approaches.
Sixteen sRNA libraries of Micro-Tom were constructed from plants stamen and pistil samples and sequenced after 2 d and 12 d of exposure to heat stress, respectively, from which a total of 110 known and 84 novel miRNAs were identified. Under heat stress conditions, 34 known and 35 novel miRNAs were differentially expressed in stamens, and 20 known and 10 novel miRNAs were differentially expressed in pistils. GO and KEGG pathway analysis showed that the predicted target genes of differentially expressed miRNAs were significantly enriched in metabolic pathways in both stamen and pistil libraries. Potential miRNA-target cleavage cascades that correlated with the regulation of stigma exsertion under heat stress conditions were found and validated through qRT-PCR and RLM-5' RACE.
Overall, a global spectrum of known and novel miRNAs involved in tomato stigma exsertion and induced by high temperatures were identified using high-throughput sequencing and molecular biology approaches, laying a foundation for revealing the miRNA-mediated regulatory network involved in the development of tomato stamens and pistils under high-temperature conditions.
栽培番茄品种的自交是从野生番茄植物的衍生特征，野生番茄植物大多是异交的。然而，环境压力会导致番茄花的形态缺陷，并阻碍自交。在高温下，番茄植物通常表现出柱头外露的表型，自花授粉和结实严重受阻，而柱头外露的内在机制迄今尚不清楚。大量小 RNA（sRNA）已被证明在植物发育和应激反应中发挥重要作用，然而，在高温条件下，它们在雄蕊和雌蕊发育方面都没有被研究过。我们使用高通量测序技术和分子生物学方法研究了柱头外露与小 RNA 之间的关系。
从 Micro-Tom 的雄蕊和雌蕊样本中构建了 16 个 sRNA 文库，并分别在暴露于热应激 2 天和 12 天后进行测序，总共鉴定出 110 个已知和 84 个新的 miRNA。在热应激条件下，34 个已知和 35 个新的 miRNA 在雄蕊中差异表达，20 个已知和 10 个新的 miRNA 在雌蕊中差异表达。GO 和 KEGG 通路分析表明，差异表达 miRNA 的预测靶基因在雄蕊和雌蕊文库中均显著富集在代谢途径中。通过 qRT-PCR 和 RLM-5' RACE 发现并验证了与高温下柱头外露调节相关的潜在 miRNA 靶标切割级联。
总之，使用高通量测序和分子生物学方法鉴定了参与番茄柱头外露并受高温诱导的已知和新的 miRNA 的全谱，为揭示高温条件下番茄雄蕊和雌蕊发育中涉及的 miRNA 介导的调控网络奠定了基础。
