Production of virus-free cassava through hot water therapy and two rounds of meristem tip culture

Abstract

Cassava genetic resources are highly threatened by devastating viral diseases. It is therefore important to conserve the specifically farmer-preferred landraces/cultivars that are highly susceptible. The study assessed the efficiency of hot water therapy and meristem tip culture techniques in the elimination of cassava mosaic disease (CMD) and cassava brown streak disease (CBSD) causal viruses. Stems of symptomatic cassava genotypes confirmed infected with cassava brown streak viruses (CBSV) and cassava mosaic viruses (CMV) were subjected to hot water therapy at varying temperatures (25°C-60°C) followed by two rounds of meristem tip culture (MTC). Data on sprouting in the screen house and response in vitro were recorded and weaned plants were indexed for CMV and CBSV. The results indicated 100% elimination of CMV and a significant reduction in the viral load of CBSV. Thus, these techniques could be integrated into the cassava conservation strategy, for sustainable management of cassava genetic resources.

Virulence and Molecular Detection of Cassava Mosaic and Brown Streak Virus Genes on Elite Mutant Cassava Lines

“…The low severity expression for CBSD and CMD under single inoculation especially by the elite mutant lines could be due to the existence of resistant genes randomly created through mutagens used in generating the lines. Conversely, the higher severity that resulted in defoliation in some lines may be an indication of synergistic effect on virulence and pathogenicity when the two viruses successfully infect a single host at the same time [19]. Similarly, the severity increase from 14 days post-inoculation to 42 days after inoculation corresponds with the findings by other researchers where after 28 days of inoculation, the severity expressions were higher on the susceptible checks than the test lines [20].…”

Efficient Elimination of Viruses from Garlic Using a Combination of Shoot Meristem Culture, Thermotherapy, and Chemical Treatment

“…Garlic is a vegetative propagated crop, and thus the accumulation of viruses over generations reduces the quantity and quality of garlic bulbs [ 14 , 28 , 40 , 41 , 42 , 43 , 44 ]. In this study, we excluded two major viruses, viz.…”

“…The conventional breeding techniques are not suitable for developing virus-resistant varieties of garlic due to its floral sterility [ 4 , 6 ]. Presently, viruses can be eliminated from these crops through different physical and chemical techniques to obtain virus-free propagating materials [ 14 , 27 , 28 , 40 , 41 , 46 ]. The efficiency of the technique depends on the type and the accumulation level of a virus in the plant, its physiology, and plants’ resistance level [ 47 ].…”

“…Meristem culture is frequently combined with thermotherapy to effectively eliminate viruses from vegetatively propagated crops, such as apple ( Malus domestica ), cassava ( Manihot esculenta ), grape ( Vitis vinifera ), garlic, potato ( Solanum tuberosum ), shallot ( Allium cepa gr. Aggregatum ), and sweet potato ( Ipomoea batatas ), and this approach has been shown to be effective in eliminating 20–100% of viruses depending on their type [ 14 , 28 , 40 , 41 , 42 , 43 , 44 , 55 ]. The combination of meristem culture with thermotherapy exhibited a higher elimination efficiency than that seen with the individual treatments.…”

Efficient conditions for in vitro establishment and regeneration of disease-free Ugandan farmer-preferred cassava genotypes

“…According to Nakabonge et al (2020), the use of meristem tip culture in combination with hot water treated removed the cassava mosaic viruses (CMV) and reduced the UCBSV in the system of the plant. To further certify the absence of viruses in the explants to be used, molecular biology techniques like the polymerase chain reaction (PCR) are being used.…”