Phytohormone and Transcriptomic Analysis Reveals Endogenous Cytokinins Affect Kiwifruit Growth under Restricted Carbon Supply
Phytohormone and Transcriptomic Analysis Reveals Endogenous Cytokinins Affect Kiwifruit Growth under Restricted Carbon Supply
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DOI：
10.3390/metabo10010023
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发表时间：
2020-01-01
期刊：
影响因子：
4.1
通讯作者：
Richardson, Annette C.
中科院分区：
文献类型：
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作者：
Nardozza, Simona;Cooney, Janine;Richardson, Annette C.
在细胞分裂之后，果实生长的特点是细胞体积的增加和细胞生物量的积累。水果生长受到碳饥饿的限制；然而，在限制碳水化合物供应条件下控制果实生长的机制尚不清楚。在之前的一项研究中，我们发现长期的碳饥饿对碳水化合物、花青素代谢和果实生长有不利影响。为了阐明猕猴桃发育过程中果实生长减少的机制，我们将植物激素分析与高碳水化合物或低碳水化合物供应下果实的转录组学和发育数据集相结合。猕猴桃外果皮组织的植物激素分析显示，碳饥饿果实中总细胞分裂素浓度降低了6倍，而其他激素的影响较小。主成分分析显示，在开花中期后16周，基于碳水化合物供应状况，不同水果的细胞分裂素组成不同。细胞分裂素生物合成基因（IPT, CYP735A）在碳饥饿下显著下调，与代谢物数据一致。几个编码扩张蛋白的基因在碳饥饿下也被下调，扩张蛋白是参与细胞壁松动的蛋白质。与其他肉质水果相比，我们的研究结果表明，细胞分裂素不仅能促进细胞分裂，还能促进猕猴桃果实细胞的扩张和生长。
Following cell division, fruit growth is characterized by both expansion through increases in cell volume and biomass accumulation in cells. Fruit growth is limited by carbon starvation; however, the mechanism controlling fruit growth under restricted carbohydrate supply is poorly understood. In a previous study using red-fleshed kiwifruit, we showed that long-term carbon starvation had detrimental effects on carbohydrate, anthocyanin metabolism, and fruit growth. To elucidate the mechanisms underlying the reduction in fruit growth during kiwifruit development, we integrated phytohormone profiling with transcriptomic and developmental datasets for fruit under high or low carbohydrate supplies. Phytohormone profiling of the outer pericarp tissue of kiwifruit showed a 6-fold reduction in total cytokinin concentrations in carbon-starved fruit, whilst other hormones were less affected. Principal component analysis visualised that cytokinin composition was distinct between fruit at 16 weeks after mid bloom, based on their carbohydrate supply status. Cytokinin biosynthetic genes (IPT, CYP735A) were significantly downregulated under carbon starvation, in agreement with the metabolite data. Several genes that code for expansins, proteins involved in cell wall loosening, were also downregulated under carbon starvation. In contrast to other fleshy fruits, our results suggest that cytokinins not only promote cell division, but also drive fruit cell expansion and growth in kiwifruit.