Alós Enriqueta, Distefano Gaetano, Rodrigo María Jesús, Gentile Alessandra, Zacarías Lorenzo
Instituto de Agroquímica y Tecnología de Alimentos (IATA), Consejo Superior de Investigaciones Científicas (CSIC), 46980, Paterna, Valencia, Spain.
Physiol Plant. 2014 Aug;151(4):507-21. doi: 10.1111/ppl.12133. Epub 2013 Dec 29.
'Tardivo' mandarin is a mutant of 'Comune' Clementine with a delay in peel degreening and coloration, allowing late harvesting. In this work, we have explored if the late-harvesting phenotype of 'Tardivo' mandarin is related to altered perception and sensitivity to ethylene. The peel degreening rate was examined after a single ethephon treatment or during a continuous ethylene application in fruits at two maturation stages. In general, ethylene-induced peel degreening was considerably delayed and reduced in fruits of 'Tardivo', as well as the concomitant reduction of chlorophyll (Chl) and chloroplastic carotenoids, and the accumulation of chromoplastic carotenoids. Analysis of the expression of genes involved in Chl degradation, carotenoids, ABA, phenylpropanoids and ethylene biosynthesis revealed an impairment in the stimulation of most genes by ethylene in the peel of 'Tardivo' fruits with respect to 'Comune', especially after 5 days of ethylene application. Moreover, ethylene-induced expression of two ethylene receptor genes, ETR1 and ETR2, was also reduced in mutant fruits. Expression levels of two ethylene-responsive factors, ERF1 and ERF2, which were repressed by ethylene, were also impaired to a different extent, in fruits of both genotypes. Collectively, results suggested an altered sensitivity of the peel of 'Tardivo' to ethylene-induced physiological and molecular responses, including fruit degreening and coloration processes, which may be time-dependent since an early moderated reduction in the responses was followed by the latter inability to sustain ethylene action. These results support the involvement of ethylene in the regulation of at least some aspects of peel maturation in the non-climacteric citrus fruit.
“塔迪沃”宽皮橘是“康敏”克莱门氏小柑橘的一个突变品种，其果皮褪绿和着色延迟，因而可以晚采。在本研究中，我们探究了“塔迪沃”宽皮橘的晚采表型是否与乙烯感知和敏感性改变有关。在两个成熟阶段的果实上，经乙烯利单次处理或连续施加乙烯后，检测了果皮褪绿速率。总体而言，乙烯诱导的“塔迪沃”果实果皮褪绿显著延迟且程度降低，同时叶绿素（Chl）和叶绿体类胡萝卜素减少，有色体类胡萝卜素积累。对参与Chl降解、类胡萝卜素、脱落酸、苯丙烷类和乙烯生物合成的基因表达分析表明，与“康敏”相比，乙烯对“塔迪沃”果实果皮中大多数基因的刺激受损，尤其是在施加乙烯5天后。此外，乙烯诱导的两个乙烯受体基因ETR1和ETR2在突变果实中的表达也降低。两种乙烯响应因子ERF1和ERF2的表达水平在两种基因型的果实中均受到不同程度的损害，它们受乙烯抑制。总体而言，结果表明“塔迪沃”果皮对乙烯诱导的生理和分子反应，包括果实褪绿和着色过程的敏感性发生了改变，这可能是时间依赖性的，因为早期反应适度降低之后，后期无法维持乙烯作用。这些结果支持乙烯参与调控非跃变型柑橘果实果皮成熟的至少某些方面。
