Caracterização da resistência da moranga (Cucurbita maxima) ´Exposição` ao Zucchini lethal chlorosis virus (ZLCV) e da não interferência de dois potyvirus na resistência das plantas

Abstract

Characterization of the resistance of winter squash (Cucurbita maxima) 'Exposição' to Zucchini lethal chlorosis virus (ZLCV) and the lack of interference of two potyviruses on plant resistance. The occurrence of lethal chlorosis in the past years, caused by Zucchini lethal chlorosis virus (ZLCV), has become common in cucurbit crops, which concerns producers in terms of yield losses. Due to the lack of information about this virus disease, only few prophylactic precautions have been recommended in order to minimize the occurrence of the disease. The genetic resistance, either via conventional means or via transgenesis, is considered the most efficient way so far to control virus diseases. With that in mind, the present work aimed to characterize the genetic resistance of winter squash "Exposição" against ZLCV in order to generate important information for cucurbit breeding programs, as well as to investigate the potential effect of Papaya ringspot virustype W (PRSV-W) and Zucchini yellow mosaic virus (ZYMV) in winter squash "Exposição" resistance against ZLCV. The ZLCV infection and its systemic mobility inside the plant were evaluated by PTA-ELISA, RT-PCR, tissue printing and biological recovery test. The results have shown that ZLCV can be detected at the infection spot, but was not detected beyond the inoculation point. These results suggest that winter squah "Exposição" is resistant to long-distance systemic invasion of ZLCV. In order to verify the potential interference of the potyviruses on the winter squash "Exposição" resistance against ZLCV, experiments were carried out into greenhouse, where the viruses were inoculated together into testing plants, and also in field trials, where the potyviruses were pre-inoculated and the infection by ZLCV naturally occurred by the vector. Interference of potyviruses on the winter squash resistance was not observed via the investigation methods presented.