Molecular basis of disease resistance in banana progenitor Musa Balbisiana against Xanthomonas Campestris pv. Musacearum

Open Access JournalBanana Xanthomonas wilt disease, caused by Xanthomonas campestris pv. musacearum (Xcm), is a major threat to banana production in east Africa. All cultivated varieties of banana are susceptible to Xcm and only the progenitor species Musa balbisiana was found to be resistant. The molecular basis of susceptibility and resistance of banana genotypes to Xcm is currently unknown. Transcriptome analysis of disease resistant genotype Musa balbisiana and highly susceptible banana cultivar Pisang Awak challenged with Xcm was performed to understand the disease response. The number of differentially expressed genes (DEGs) was higher in Musa balbisiana in comparison to Pisang Awak. Genes associated with response to biotic stress were up-regulated in Musa balbisiana. The DEGs were further mapped to the biotic stress pathways. Our results suggested activation of both PAMP-triggered basal defense and disease resistance (R) protein-mediated defense in Musa balbisiana as early response to Xcm infection. This study reports the first comparative transcriptome profile of the susceptible and resistant genotype of banana during early infection with Xcm and provide insights on the defense mechanism in Musa balbisiana, which can be used for genetic improvement of commonly cultivated banana varieties

Mechanisms and approaches towards enhanced drought tolerance in cassava (Manihot esculenta)

Open Access Article; Published online: 02 Nov 2021Cassava (Manihot esculenta Crantz) is cultivated in tropical and subtropical regions for its edible tuberous roots and minimally for its leaves. It provides food and revenue to over eight hundred million people particularly in Africa. Generally, cassava is drought-tolerant, and sheds leaves in drought conditions resulting in significantly lower yields. Cassava drought management strategies need to focus on maximizing the utilization of molecular tools for crop establishment and yield. Developing strategies to produce cassava cultivars with drought tolerance is vital to extending crop yield under limited rainfall. In this review, recent progress applying molecular genetics, genomics, genetic engineering, and genome editing are reviewed

Dominant allele phylogeny and constitutive subgenome haplotype inference in bananas using mitochondrial and nuclear markers

Article purchased; Published online: 27 Aug 2017Cultivated bananas (Musa spp.) have undergone domestication patterns involving crosses of wild progenitors followed by long periods of clonal propagation. Majority of cultivated bananas are polyploids with different constitutive subgenomes and knowledge on phylogenies to their progenitors at the species and subspecies levels is essential. Here, the mitochondrial (NAD1) and nuclear (CENH3) markers were used to phylogenetically position cultivated banana genotypes to diploid progenitors. The CENH3 nuclear marker was used to identify a minimum representative haplotype number in polyploids and diploid bananas based on single nucleotide polymorphisms. The mitochondrial marker NAD1 was observed to be ideal in differentiating bananas of different genomic constitutions based on size of amplicons as well as sequence. The genotypes phylogenetically segregated based on the dominant genome; AAB genotypes grouped with AA and AAA, and the ABB together with BB. Both markers differentiated banana sections, but could not differentiate subspecies within the A genomic group. On the basis of CENH3 marker, a total of 13 haplotypes (five in both diploid and triploid, three in diploids, and rest unique to triploids) were identified from the genotypes tested. The presence of haplotypes, which were common in diploids and triploids, stipulate possibility of a shared ancestry in the genotypes involved in this study. Furthermore, the presence of multiple haplotypes in some diploid bananas indicates their being heterozygous. The haplotypes identified in this study are of importance because they can be used to check the level of homozygozity in breeding lines as well as to track segregation in progenies

Cassava (Manihot esculenta) dual use for food and bioenergy: a review

Open Access Journal; Published online: 24 Mar 2022Cassava (Manihot esculenta. Crantz) is a starch-rich, woody tuberous, root crop important for food, with little being done to investigate its potential as a bioenergy crop despite its enormous potential. The major bottleneck in the crop being able to serve this dual role is the competition of its storage roots for both purposes. The major cassava production regions primarily use the tuberous roots for food, and this has resulted in its neglect as a bioenergy crop. The use of non-food cassava parts as a feedstock in cellulosic biofuel production is a promising strategy that can overcome this challenge. However, in non-tuber parts, most of the sugars are highly sequestered in lignin complexes making them inaccessible to bacterial bioconversion. Additionally, cassava production in these major growing areas is not optimal owing to several production constraints. The challenges affecting cassava production as a food and bioenergy crop are interconnected and therefore need to be addressed together. Cassava improvement against biotic and abiotic stresses can enhance productivity and cater for the high demand of the roots for food and bioenergy production. Furthermore, increased production will enhance the usability of non-food parts for bioenergy as the bigger goal. This review addresses efforts in cassava improvement against stresses that reduce its productivity as well as strategies that enhance biomass production, both important for food and bioenergy. Additionally, prospective strategies that could ease bioconversion of cassava for enhanced bioenergy production are explored

Improvement of nutraceutical traits of banana: new breeding techniques

Published online: 07 Jul 2023Banana (Musa spp.) is an herbaceous, everlasting green monocotyledonous plant belonging to the family Musaceae. It is a major staple crop after rice, maize, wheat, potato and cassava, and it has a high potential to contribute to food and nutrition security. It is an excellent fruit full of micronutrients, especially vitamin A, iron, potassium, and magnesium, and is a source of energy for millions of inhabitants of tropical and subtropical regions. Despite these qualities, banana is still lacking in various essential nutrients. The conventional breeding program aims to increase the nutritional quality of banana. Still, the program is facing severe challenges due to the sterile seedless nature of banana and the narrow genetic diversity of several banana cultivars. Accessibility of well-annotated Musa genome sequences and established transformation and gene-editing platforms can contribute to developing banana with high dietary value. Furthermore, banana can produce edible vaccines, paving the way for future syringe-less vaccine development. This book chapter describes the various aspects of nutrition and the health-related importance of banana