The 5th 2023 IPPS seminar will held on Wednesday 6 December at 4:00 pm central European time. We will have the following talks:
Jeanmaire Molina, from Pace University, USA will present work on “Reviving the corpse flower: unraveling the enigmatic biology of the iconic plant parasite Rafflesia for ex situ conservation”
Jian You (Eric) Wang, from King Abdullah University of Science and Technology, Saudi Arabia will talk about “Disruption of the rice MORE AXILLARY GROWTH1 (MAX1) uncovers specific functions of canonical strigolactones in the rhizosphere”, and
Sylvia Mutinda, of Kenyatta University, Kenya will discuss “Allele mining of the sorghum accession panel unravels new lgs1-1 mutants with resistance to the parasitic plant Striga”.
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Jeanmaire Molina – A rare spectacle to behold, Rafflesia’s massive red-orange bloom stands out in the rainforest, with a malodor targeting carrion flies—hence the common name corpse flower–yet people are equally drawn to it. Unique to the rapidly deteriorating rainforests of Southeast Asia, Rafflesia species are in danger of extinction. Much like the panda, a charismatic icon of conservation, but unlike it, we don’t understand enough of Rafflesia biology to cultivate it. Rafflesia is an endophytic holoparasite, completely dependent on its host vine Tetrastigma for nutrition, living inside it throughout its life and only emerging to flower. However, only a few Tetrastigma species support an infection, and it is unknown what makes certain species susceptible. Since 2015, I have been collaborating with the US Botanic Garden on the ex situ propagation of Philippine Rafflesia in the US, and we have been attempting to grow propagules of Rafflesia and their Tetrastigma hosts in Washington DC. Over the years, we’ve only had incremental success, but we have uncovered various aspects of Rafflesia’s enigmatic biology—from understanding the effects of a Rafflesia infection on host chemistry, to elucidating the genetics of the Rafflesia seed, as well as characterizing its microbial symbionts. Our results have horticultural applications and bring us a step closer to growing Philippine Rafflesia in the US.Towards this end, I am also using my platform as a college teacher to engage young people here and abroad in plant research, so we not only cultivate Rafflesia, but also future scientists who will be able to carry on biodiversity conservation. Timing is critical, because once extinct, we can no longer revive the corpse flower.
Jian You (Eric) Wang got his Ph.D. in Bioscience under the supervision of Salim Al-Babili at King Abdullah University of Science and Technology (KAUST) in 2021. He was involved in international collaborative research projects focusing on the novel carotenoid-derived molecule called zaxinone. After that, he continued his postdoc training with Salim on the Striga project funded by the Bill & Melinda Gates Foundation to investigate strigolactone biosynthesis in rice and pearl millet. In short, Eric uses analytical biochemistry to identify metabolites and combines transcriptomic strategies to study growth-regulatory metabolism.
Strigolactones (SLs) exert various biological functions as a plant hormone and signaling molecules. They are best known for their role in regulating shoot architecture, inhibiting branching/tillering, and promoting symbiosis with mycorrhizal fungi. However, released SLs also induce seed germination in root parasitic weeds, such as Striga hermonthica, paving the way for host infestation. Rice and many other plants contain two types of SLs, i.e., canonical and non-canonical, defined by their structure. Albeit the progress that has been made in SL biology, the question of whether the two SL sub-families and their members have specific functions remains largely unanswered. However, identifying specific functions of the two SL subfamilies may enable the development of Striga-resistant cereals and/or engineering plant architecture. Currently, we showed that CRISPR/Cas9 rice mutants lacking canonical SLs do not exhibit the high tillering and dwarf phenotypes characteristic for SL-deficient plants, but release exudates with a significantly reduced Striga seed-germinating activity. This result indicates a particular function of canonical strigolactones as rhizospheric signals. Furthermore, genetic analysis of further SL mutants affected in the biosynthesis of canonical SLs demonstrate that a particular canonical SL plays a specific role in regulating root and shoot development as well as in rhizospheric communications. In conclusion, our work uncovers that rice canonical SLs are not tillering regulators, identifies specific hormonal functions of canonical strigolactones, paves the way for targeted engineering of rice architecture, and opens up the possibility of developing cereals with increased resistance to root parasitic weeds.
Sylvia Mutinda is a Doctorate student of Molecular Biology and Biotechnology at Pan African University, Institute for Basic Sciences, Technology and Innovation. She doubles up as a research fellow at the Runo Lab, Kenyatta University, Kenya. Sylvia holds a Master’s degree in Biotechnology from Jomo Kenyatta University of Agriculture and Technology. Upon completion, she obtained a PhD fellowship from the Pan African University, an African Union initiative and which she’s currently finalising. She is a Mawazo fellow at The Mawazo Institute – a Kenyan-based organisation supporting the next generation of African women researchers and the uptake of home-grown and evidence-based solutions to local and global development needs. Sylvia’s research focus has been on use of advances in plant sciences (genomics, genetics and molecular biology) to manage the parasitic plant, Striga, which greatly limit production of Africa’s most staple cereals. In 2022, she was awarded research grants from the International foundation for Science (IFS) and the Mawazo fellows fund to support her research in harnessing natural sources of Striga resistance in sorghum.
Sorghum is a food staple for millions of people in sub-Saharan Africa, but its production is greatly diminished by parasitic weeds of the Striga genus. An efficient and cost-effective way of managing Striga in smallholder farms of Africa is to deploy resistant varieties. Here, we leverage genomics and the vast genetic diversity of sorghum – evolutionarily adapted to cope with Striga parasitism in Africa – to identify new Striga resistant sorghum genotypes. We exploit a Striga resistance mechanism that hinges on essential communication molecules – strigolactones (SLs) exuded by hosts to trigger parasite seed germination. We mined for mutant alleles of the LOW GERMINATION LOCI 1 (LGS1) that are ineffective in stimulating Striga germination from the sorghum accession panel (SAP). Our analysis led us to identify new lgs1-1 sorghum genotypes which we named SAP- lgs1-1. SAP lgs1 had the SL exudation profile of known lgs1-1 sorghum whose hallmark is production of the low inducer of germination, orobanchol. Laboratory and field resistance screens showed that the SAP-lgs1-1 genotypes also exhibited remarkable resistance against Striga. By potentially reducing crop losses due to Striga parasitism, our findings have far-reaching implications for improving food security in Africa.