Plant gene families have expanded many folds as opposed to animals to compensate for being sessile as well as having unique features like ability to photosynthesise. While different protein families are well characterised in plants, similar knowledge on miRNA families is still in its infancy. The family plays important role in various plant development processes including vegetative to reproductive phase change, floral patterning, nodulation, and fruit ripening as well as also in response to different environmental cues. However, analysis of this family in tomato () is limited. In this study, we identified four new loci (-) and two new isoforms, other than those reported at the miRBase repository. The family has expanded by segmental duplication events and is conserved between the wild (. and . ) and the cultivated tomato varieties. However, phylogenetic analysis showed that formed the most divergent member within each clade and . is closer to the cultivated varieties. Additionally, investigations in 42 plant species highlighted that miR172a/b is the most abundant form in the plant kingdom. In addition to the classical target (), degradome analysis identified () as a novel target of Sly-miR172 that was validated using precursor:effector and target:reporter transient assays. Further, we report dual mode of Sly-miR172-mediated silencing of targets - and by post-transcriptional transcript cleavage as well as translational repression. Different members of and exhibit inverse expression correlation in response to different abiotic stresses, suggesting their role in stress response. Functional investigation of showed that tomato plants performed better in different abiotic stresses (heat, drought, and salt) upon overexpression or target knock-down by virus-induced-gene-silencing. Conversely, when miRNA is chelated using short-tandem-target-mimic, the plants exhibit sensitivity to these stresses. Thus, Sly-miR172 acts as a positive regulator while its targets and as negative regulators of different abiotic stresses.

中文翻译：

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非生物胁迫下番茄 miR172 亚型的功能多样化

植物基因家族比动物基因家族扩大了许多倍，以补偿其无柄性以及具有光合作用能力等独特特征。虽然植物中不同的蛋白质家族得到了很好的表征，但对 miRNA 家族的类似了解仍处于起步阶段。该家族在各种植物发育过程中发挥着重要作用，包括营养阶段到生殖阶段的转变、花型、结瘤和果实成熟，以及对不同环境信号的反应。然而，对番茄（）中这个家族的分析是有限的。在这项研究中，除了 miRBase 存储库中报告的那些之外，我们还鉴定了四个新基因座 (-) 和两个新亚型。该家族通过片段复制事件而扩展，并且在野生（.和.）和栽培番茄品种之间保守。然而，系统发育分析表明，形成了每个进化枝内最不同的成员。与栽培品种较为接近。此外，对 42 个植物物种的研究强调，miR172a/b 是植物界中最丰富的形式。除了经典靶点 () 之外，降解组分析还确定 () 为 Sly-miR172 的新靶点，并使用前体：效应子和靶点：报告基因瞬时测定进行了验证。此外，我们报告了 Sly-miR172 介导的靶标沉默的双重模式——通过转录后转录物切割以及翻译抑制。和 的不同成员在响应不同的非生物胁迫时表现出逆表达相关性，表明它们在胁迫反应中的作用。功能研究表明，番茄植株在不同的非生物胁迫（热、干旱和盐）下，在病毒诱导的基因沉默过度表达或目标敲低后表现得更好。相反，当使用短串联靶标模拟物螯合 miRNA 时，植物对这些胁迫表现出敏感性。因此，Sly-miR172 充当正调节因子，而其靶标则充当不同非生物胁迫的负调节因子。