PJB-2018-972
INDUCTION AND IDENTIFICATION OF AUTOTETRAPLOIDY IN CUCUMBER BY COLCHICINE TREATMENT
Jinshuang Zheng
Abstract
Cucumber, Cucumis sativus L. (2n = 2x = 14), is one of important vegetable in worldwide. Polyploidy induction is expected to increase its breeding potential. The objective of this work was to develop and characterize three ecotype cucumber autotetraploids through colchicine-based induction. Autotetraploid cucumber plants were produced by colchicine using the treatment method of growing point of seedlings at the emergence of cotyledon stage with different concentrations (0, 0.1%, 0.2% and 0.3%) and times (3, 5 and 7 applications). The treatment with 0.2% for 5 or 7 times and 0.3% for 5 times were proved to be more effective in producing autotetraploids. Polyploids were preliminary screened by morphological characteristics and stomatal apparatus, then detected by flow cytometry (FCM) and confirmed by chromosome counting. As expected, the chromosome number was 2n = 2x = 14 in diploids, and 2n= 2x = 28 in the autotetraploid. The basic genome size was not altered in the third generation progeny from all treated plants. The polyploid plants were accompanied by larger leaf size, flower dimeter, stoma size, chloroplast number in guard cells and pollen grains, but decrease in stomata density, fruit size and normal pollen rate. Results indicated that an efficient method for the induction and identification of tetraploids in cucumberwas established by morphological changes, stomata size, number of chloroplasts per guard cell, FCM and chromosome counting successively. This will facilitate the manipulation of ploidy level for developing novel elite germplasm and further analysis of the mechanism of polyploidy in cucumber.
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