Biology subjects

Yoder, J.

Publications and source records attributed to Yoder, J..

2 recordsLinked to original sources

bioRxiv2024

The evolution of pectate lyase-like genes across land plants, and their roles in haustorium formation in parasitic plants

Parasitic plants in Orobanchaceae are noxious agricultural pests that severely impact crops worldwide. These plants acquire water and nutrients from their hosts through a specialized organ called the haustorium. A key step in haustorium development involves cell wall modification. In this study, we identified and analyzed the evolutionary relationships of pectate lyase-like (PLL) genes across parasitic plants and other non-parasitic land plant lineages. To support detailed examination of gene models and paralogous gene family members, we used published parasitic plant genomes, as well as a recently generated draft genome assembly and annotation of Triphysaria versicolor. One particular PLL gene, denoted as PLL1 in parasitic Orobanchaceae, emerged as an important candidate gene for parasitism. Our previous comparative transcriptomic analyses showed that PLL1 underwent neofunctionalization via an expression shift from floral tissues in non-parasitic relatives to haustoria in parasitic species. It belongs to the largest sub-clade of the PLL gene family, is highly upregulated in haustoria, and shows signatures of relaxed purifying selection and 15 individual sites with signatures of adaptive evolution. To explore its function in haustorium development, we manipulated PLL1 expression in T. versicolor, a model parasitic species from Orobanchaceae, using direct transformation with the parasite and host-induced-gene-silencing (HIGS). For HIGS, we generated transgenic Medicago hosts expressing hairpin RNAs targeting the PLL1 gene in T. versicolor. An average 60% reduction of PLL1 transcript level was observed in both direct transformation and HIGS treatments, leading to an increased frequency of poorly adhered parasites with fewer xylem connections and a smaller proportion of mature haustoria. These findings demonstrate that PLL1 plays a crucial role in haustorium development and suggest it as a promising target for managing parasitic weeds. Notably, the success of HIGS even before the establishment of a functional haustorium highlights the possibility of early intervention against parasitism.

plant biology↗

bioRxiv2020

Classification and characterisation of livestock production systems in northern Tanzania

Livestock keepers in sub-Saharan Africa face a growing range of pressures, including climate change, land loss, restrictive policies, and population increase. Widespread adaptation in response to such pressures can lead to the emergence of new, non-traditional typologies of livestock production. We sought to characterise livestock production systems in northern Tanzania, a region undergoing rapid social, economic, and environmental change. Questionnaire and spatial data were collected from 404 livestock-keeping households in 21 villages in Arusha and Manyara Regions in 2016. Multiple factor analysis and hierarchical cluster analysis were used to classify households into livestock production systems based on household-level characteristics. Indicators of vulnerability, including household-level reports of hunger, illness, livestock loss, land loss and crop losses were compared between production systems. Three distinct clusters emerged through this process. The ethnic, environmental and livestock management characteristics of households in each cluster broadly mapped onto traditional definitions of pastoral, agro-pastoral and smallholder livestock production in the region, suggesting that this quantitative classification system is complementary to more qualitative classification methods. Our findings also suggest that traditional systems of livestock production continue to persist in northern Tanzania. Nonetheless, we found indicators of substantial change within livestock production systems, most notably the adoption of crop agriculture in the majority of pastoral households. Smallholder households were less likely than either pastoral or agro-pastoral households to report hunger, illness, and livestock, land or crop losses. Livelihoods that rely solely on livestock are relatively rare in northern Tanzania, which represents an important shift in production in the region, particularly among pastoralists. Policy initiatives to improve household and community well-being should recognise the continuing distinctiveness of traditional livestock production systems in the region.

systems biology↗