Lin Zhefeng, Hong Yiguo, Yin Mingan, Li Chunyang, Zhang Ke, Grierson Don
Plant Sciences Division, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, LE12 5RD, UK.
Plant J. 2008 Jul;55(2):301-10. doi: 10.1111/j.1365-313X.2008.03505.x. Epub 2008 Apr 4.
Ethylene is required for climacteric fruit ripening. Inhibition of ethylene biosynthesis genes, 1-aminocyclopropane-1-carboxylate (ACC) synthase and ACC oxidase, prevents or delays ripening, but it is not known how these genes are modulated during normal development. LeHB-1, a previously uncharacterized tomato homeobox protein, was shown by gel retardation assay to interact with the promoter of LeACO1, an ACC oxidase gene expressed during ripening. Inhibition of LeHB-1 mRNA accumulation in tomato fruit, using virus-induced gene silencing, greatly reduced LeACO1 mRNA levels, and inhibited ripening. Conversely, ectopic overexpression of LeHB-1 by viral delivery to developing flowers elsewhere on injected plants triggered altered floral organ morphology, including production of multiple flowers within one sepal whorl, fusion of sepals and petals, and conversion of sepals into carpel-like structures that grew into fruits and ripened. Our findings suggest that LeHB-1 is not only involved in the control of ripening but also plays a critical role in floral organogenesis.
跃变型果实成熟需要乙烯。抑制乙烯生物合成基因1-氨基环丙烷-1-羧酸（ACC）合成酶和ACC氧化酶可防止或延缓果实成熟，但尚不清楚这些基因在正常发育过程中是如何被调控的。LeHB-1是一种先前未被鉴定的番茄同源异型框蛋白，凝胶阻滞试验表明它与LeACO1（一种在成熟过程中表达的ACC氧化酶基因）的启动子相互作用。利用病毒诱导的基因沉默抑制番茄果实中LeHB-1 mRNA的积累，可大大降低LeACO1 mRNA水平，并抑制果实成熟。相反，通过病毒介导将LeHB-1异位过表达到注射植株上其他部位正在发育的花中，会引发花器官形态改变，包括在一个萼片轮中产生多朵花、萼片和花瓣融合，以及萼片转化为心皮状结构并发育成果实并成熟。我们的研究结果表明，LeHB-1不仅参与果实成熟的调控，还在花器官发生中起关键作用。
