Small-RNA Deep Sequencing Reveals Arctium tomentosum as a Natural Host of Alstroemeria virus X and a New Putative Emaravirus

Peer reviewe

Genetic Variability and Evolutionary Implications of RNA Silencing Suppressor Genes in RNA1 of Sweet Potato Chlorotic Stunt Virus Isolates Infecting Sweetpotato and Related Wild Species

Peer reviewe

Comparative analysis of sorghum (C4) and rice (C3) plant headspace volatiles induced by artificial herbivory

Acute stress responses include release of defensive volatiles from herbivore-attacked plants. Here we used two closely related monocot species, rice as a representative C3 plant, and sorghum as a representative C4 plant, and compared their basal and stress-induced headspace volatile organic compounds (VOCs). Although both plants emitted similar types of constitutive and induced VOCs, in agreement with the close phylogenetic relationship of the species, several mono- and sesquiterpenes have been significantly less abundant in headspace of sorghum relative to rice. Furthermore, in spite of generally lower VOC levels, some compounds, such as the green leaf volatile (Z)-3-hexenyl acetate and homoterpene DMNT, remained relatively high in the sorghum headspace, suggesting that a separate mechanism for dispersal of these compounds may have evolved in this plant. Finally, a variable amount of several VOCs among three sorghum cultivars of different geographical origins suggested that release of VOCs could be used as a valuable resource for the increase of sorghum resistance against herbivores

Changing Dynamics in the Spread and Management of Banana Xanthomonas Wilt Disease in Uganda Over Two Decades

Banana Xanthomonas wilt (BXW) is a destructive disease caused by Xanthomonas vasicola pv. musacearum (Xvm), a bacterium that indiscriminately infects all banana varieties grown in East and Central Africa (ECA). In this region, BXW was first reported in 2001 in Uganda and was projected to eliminate >90% of Uganda's banana crops (worth USD4 billion) if not controlled in less than 10 years. Lack of basic information led to application of control approaches that were based on similarity of BXW symptoms to those of Moko disease of banana. However, the approaches were unsuccessful and, in 7 to 9 years, BXW had covered six countries and threatened to wipe out the banana industry in ECA. However, BXW has been tamed to date, mainly due to relentless and systematic deployment of carefully crafted and packaged cultural control practices based on epidemiological information generated within target banana cropping ecosystems. In Uganda, the initial “top-down” communication approaches reached >85% of banana farming communities but did not mobilize the communities enough into action; hence, only 30% impact in controlling BXW was registered. In contrast, participatory approaches mobilized farming communities into action and effectively controlled BXW at field and community levels to near eradication. The approaches effectively controlled BXW in Uganda and, consequently, in eastern Kenya, northern Tanzania, Rwanda, Burundi, and the Democratic Republic of Congo. This article reviews step-wise processes leading to success over the 2 decades and identifies critical research gaps. Deployment of resistant genotypes is urgently needed as a significant addition to the BXW management toolbox to create BXW-free banana cropping systems in ECA. [Graphic: see text] Copyright © 2023 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license

Early Withering of Enlarged Ovules in Pollinated Fruits of Bananas (<i>Musa</i> spp.) Suggest Abortion after Fertilization

Sterility in edible bananas is as a result of a long history of anthropogenic-driven selection for sterile genotypes, since seed is not desirable in fruit pulp for human consumption. However, this poses a challenge to conventional genetic improvement by slowing breeding pipelines. In this study, we investigated whether pollen tubes reach all parts of the ovary, the position of fertilized ovule development in fruits, and potential seed set in selected banana genotypes. We selected four cultivars of East African Highland Cooking bananas (EAHBs), a Matooke hybrid ‘222K-1’, improved diploid ‘2905’, and wild bananas ‘Zebrina (G.F.)’ and ‘Calcutta 4’. There was evidence of pollen tubes in the distal, mid and proximal sections of the fruit, irrespective of hand position and genotype. Fertilization, as indicated by an increase in ovule size, happened along the entire length of the fruit but complete development was biased at the distal end in some genotypes. There were some differences in ovule fertilization rates between hands, with distal hands having more ovules and higher ovule fertilization rates. Ovule fertilization happens in bananas but the vast majority aborts, especially at the proximal end of the ovary. Ovule fertilization rates are generally much lower than available ovules

Percentage nucleotide (upper triangle) and deduced amino acid identities (lower triangle) of the coat protein genes of three isolates of <i>Alstroemeria virus X</i> and other potexviruses (see Table 1 for sequence accession numbers).

<p>Percentage nucleotide (upper triangle) and deduced amino acid identities (lower triangle) of the coat protein genes of three isolates of <i>Alstroemeria virus X</i> and other potexviruses (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0042758#pone-0042758-t001" target="_blank">Table 1</a> for sequence accession numbers).</p

Viral sequences obtained from public databases and used in the study.

a<p>The CP (AlsVX) or partial NP gene sequence (WBYVV) was determined in this study by amplification of the viral genomic region using RT-PCR and sequencing of the products.</p>b<p>Established and putative members of the genus.</p

Leaves of woolly burdock (<i>A. tomentosum</i>) plants with and without virus-like symptoms.

<p>Plants Vi4, Vi5 and Vi8 (orange labels) were infected with WBYVV and the leaves display vein yellowing and mosaic symptoms. Plants were photographed in the Viikki Research Farm area on May 18, 2011.</p

Phylogenetic analysis of partial putative nucleocapsid protein (NP) gene sequences (518 nt; RNA3) of established and putative members of genus <i>Emaravirus</i>.

<p>The NP gene sequence of <i>Pigeonpea sterility mosaic virus</i> is not available and could not be included. Bootstrap values higher than 80 (of 100 replicates) are indicated on the branches. For accession numbers, see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0042758#pone-0042758-t001" target="_blank">Table 1</a>. Bar indicates 0.1 Kimura units <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0042758#pone.0042758-Kimura1" target="_blank">[34]</a>.</p