Inducing autotetraploids in cassava using oryzalin and colchicine and their in vitro morphophysiological effects

Abstract

ABSTRACT. Polyploid induction has been used for plant breeding to produce bigger and more robust plants than diploid types. The present study aimed to develop a methodology for in vitro induction of polyploidy in cassava. Apical and lateral microcuttings from the BRS Formosa variety were treated with six oryzalin concentrations for 24 and 48 h. The same methodology was used for colchicine with different concentrations. After 45 days of cultivation and an additional 45 days of subculture, the viability of the explants was assessed and plant acclimatization was performed. Ploidy was determined using flow cytometry. Oryzalin dose and exposure negatively affected cassava explant growth and development compared to untreated explants. Furthermore, apical and lateral explants responded differently to the treatments, showing a diversity in antimitotic sensitivity and effect that is tissue-type specific. In contrast, the doses of 1.25 to 6.25 mM colchicine resulted in high mortality of cassava explants. Therefore, the type of antimitotic affects the morphophysiological behavior of cassava plants in vitro, although apical explants have higher viability and regenerative capacity compared to lateral explants. In addition, the lateral explants have lower mixoploid rates compared to apical explants. Of the 310 plants generated by oryzalin treatments, 277 were diploid, 31 were mixoploid, and 2 were tetraploid. Exposure to oryzalin led to low rate of tetraploids and colchicine caused phytotoxic reactions and death of the explants. The tetraploids were multiplied in vitro to evaluate their yield in the field as well as their behavior against abiotic and biotic stress.

Colchicine-Induced Polyploidy in Rhododendron fortunei Lindl

“…Higher chlorophyll content is a frequently observed event in polyploid induction in diverse plant species [39,40]. In our study, higher chlorophyll content was detected in polyploid R. fortunei plantlets, explaining the observed darker green of polyploid leaves (Table 5).…”

“…In our study, higher chlorophyll content was detected in polyploid R. fortunei plantlets, explaining the observed darker green of polyploid leaves (Table 5). Similarly, tetraploids of cassava (Manihot esculenta) were found to have higher chlorophyll content, which increased photosynthetic capacity and led to higher yield compared with diploids [40]. In Stevia rebaudiana, tetraploids also had a significantly higher chlorophyll content than diploid plants, resulting in higher photosynthetic capacity [39].…”

Tetraploidization Increases the Contents of Functional Metabolites in Cnidium officinale

“…Oryzalin is more effective than colchicine in genome doubling of orchids and cassava [24,29]. In previous studies, polyploids were induced using oryzalin at concentrations ranging from approximately 289 µM to 15 mM [23,29]. In addition to the antimitotic concentration, also the treatment method and the treatment time also affect tetraploid induction in plants [29].…”

“…Because colchicine is toxic to plants and humans [24][25][26], oryzalin and trifluralin have emerged as alternative chemicals for polyploid induction [27,28]. Oryzalin is more effective than colchicine in genome doubling of orchids and cassava [24,29]. In previous studies, polyploids were induced using oryzalin at concentrations ranging from approximately 289 µM to 15 mM [23,29].…”

“…In previous studies, polyploids were induced using oryzalin at concentrations ranging from approximately 289 µM to 15 mM [23,29]. In addition to the antimitotic concentration, also the treatment method and the treatment time also affect tetraploid induction in plants [29]. Carvalho et al [29] reported that the growth of cassava plants was inhibited when exposed to oryzalin-containing liquid medium for 2 days.…”