Biology subjects

Concha, C.

Publications and source records attributed to Concha, C..

4 recordsLinked to original sources

bioRxiv2025

Development and evaluation of screwworm, Cochliomyia hominivorax, transgenic sexing strains with embryonic gene promoters for a genetic control program

The New World screwworm, Cochliomyia hominivorax, was eradicated from North and Central America through the first application of the sterile insect technique. The sterile screwworm adult fly releases were mixed sex, but experience with other flies suggests that releasing only males could be up to five times more effective. Here we describe screwworm transgenic sexing strains (TSSs) with expected embryo lethality developed using the Tetracycline-off (Tet-off) system with the Lucilia cuprina nullo (DR6) or C. macellaria CG14427 (DR7) gene promoters and a tTA activated effector to promote female lethality. The TSSs expressed tTA highest in 2-3 h embryos and low in larvae and adults. However, most strains showed high expression in pupae. Evaluation on two doxycycline (Dox) regimens found that inclusion of Dox in the last larval feeding rescued females of the subsequent generation, likely by maternal Dox transfer to embryos. All TSSs produced only males on a reduced Dox feeding regimen but the female lethal period for the DR6 TSS was too late in development to save diet costs. Production parameters were met by all strains in colony, but strains had lower male fly survival than current production strains after removing Dox. In non-competitive mating success trials DR6 strains performed poorly, but DR7 performed equally to production strain males. However, males from all TSSs faired poorly in mating competition tests against production males. Our study highlights the importance of tightly-regulated gene promoters and suitable antibotics feeding schemes for the development and evaluation of TSSs based on Tet-off system.

biochemistry↗

bioRxiv2020

Chickpea (Cicer arietinum L.) root system architecture adaptation to initial soil moisture improves seed development in dry-down conditions

Soil water deficit (WD) impacts vascular plant phenology, morpho-physiology, and reproduction. Chickpea, which is mainly grown in semi-arid areas, is a good model plant to dissect mechanisms involved in drought resistance. We used a rhizobox-based phenotyping system to simultaneously and non-destructively characterise root system architecture (RSA) dynamics and water use (WU) patterns. We compared the drought-adaptive strategies of Teketay to the drought-sensitive genotype ICC 1882 in high and low initial soil moisture without subsequent irrigation. WD restricted vegetative and reproductive organ biomass for both genotypes. Teketay displayed greater adaptability for RSA dynamics and WU patterns and revealed different drought adaptive strategies depending on initial soil moisture: escape when high, postponement when low. These strategies were manifested in distinct RSA dynamics: in low initial soil moisture, its reduced root growth at the end of the vegetative phase was followed by increased root growth in deeper, wetter soil strata, which facilitated timely WU for seed development and produced better-developed seeds. We demonstrate that RSA adaptation to initial soil moisture is one mechanism by which plants can tolerate WD conditions and ensure reproduction by producing well-developed seeds. Our approach will help in identifying the genetic basis for large plasticity of RSA dynamics which enhances the resilience with which crops can optimally adapt to various drought scenarios. HighlightRoot system architecture and water use patterns change dynamically for distinct drought adaptation strategies in chickpea.

plant biology↗

bioRxiv2020

The gene cortex controls scale colour identity in Heliconius

In Heliconius butterflies, wing pattern diversity is controlled by a few genes of large effect that regulate colour pattern switches between morphs and species across a large mimetic radiation. One of these genes, cortex, has been repeatedly associated with colour pattern evolution in butterflies. Here we carried out CRISPR knock-outs in multiple Heliconius species and show that cortex is a major determinant of scale cell identity. Chromatin accessibility profiling and introgression scans identified cis-regulatory regions associated with discrete phenotypic switches. CRISPR perturbation of these regions in black hindwing genotypes recreated a yellow bar, revealing their spatially limited activity. In the H. melpomene/timareta lineage, the candidate CRE from yellow-barred phenotype morphs is interrupted by a transposable element, suggesting that cis-regulatory structural variation underlies these mimetic adaptations. Our work shows that cortex functionally controls scale colour fate and that its cis-regulatory regions control a phenotypic switch in a modular and pattern-specific fashion.

evolutionary biology↗

bioRxiv2019

Affordable and robust phenotyping framework to analyse root system architecture of soil-grown plants

The analysis of root system growth, root phenotyping, is important to inform efforts to enhance plant resource acquisition from soils. However, root phenotyping remains challenging due to soil opacity and requires systems that optimize root visibility and image acquisition. Previously reported systems require costly and bespoke materials not available in most countries, where breeders need tools to select varieties best adapted to local soils and field conditions. Here, we present an affordable soil-based growth container (rhizobox) and imaging system to phenotype root development in greenhouses or shelters. All components of the system are made from commodity components, locally available worldwide to facilitate the adoption of this affordable technology in low-income countries. The rhizobox is large enough (~6000 cm2 visible soil) to not restrict vertical root system growth for at least seven weeks after sowing, yet light enough (~21 kg) to be routinely moved manually. Support structures and an imaging station, with five cameras covering the whole soil surface, complement the rhizoboxes. Images are acquired via the Phenotiki sensor interface, collected, stitched and analysed. Root system architecture (RSA) parameters are quantified without intervention. RSA of a dicot (chickpea, Cicer arietinum L.) and a monocot (barley, Hordeum vulgare L.) species, which exhibit contrasting root systems, were analysed. The affordable system is relevant for efforts in Ethiopia and elsewhere to enhance yields and climate resilience of chickpea and other crops for improved food security.\n\nSignificance StatementAn affordable system to characterize root system architecture of soil-grown plants was developed. Using commodity components, this will enable local efforts world-wide to breed for enhanced root systems.

plant biology↗