A temporal atlas and response to nitrate availability of 3D root system architecture in diverse pennycress (Thlaspi arvenseL.) accessions

Abstract

Roots have a central role in plant resource capture and are the interface between the plant and the soil that affect multiple ecosystem processes. Field pennycress (Thlaspi arvense L.) is a diploid annual cover crop species that has potential utility for reducing soil erosion and nutrient losses; and has rich seeds (30-35% oil) amenable to biofuel production and as a protein animal feed. The objective of this research was to (1) precisely characterize root system architecture and development, (2) understand adaptive responses of pennycress roots to nitrate nutrition, (3) and determine genotypic variance available in root development and nitrate plasticity. Using a root imaging and analysis pipeline, 4D pennycress root system architecture was characterized under four nitrate regimes (from zero to high nitrate concentration) across four time points (days 5, 9, 13, and 17 after sowing). Significant nitrate condition response and genotype interactions were identified for many root traits with greatest impact on lateral root traits. In trace nitrate conditions a greater lateral root count, length, interbranch density, and a steeper lateral root angle was observed compared to high nitrate conditions. Genotype-by-nitrate condition interaction was observed for root width, width:depth ratio, mean lateral root length, and lateral root density. These results illustrate root trait variance available in pennycress accessions that could be useful targets for breeding of improved nitrate responsive cover crops for greater productivity, resilience, and ecosystem service.

Pennycress domestication and improvement efforts

“…In addition, pennycress lateral roots were found to be the most responsive under varying nitrate concentrations, similar to those observed in several crops, including Arabidopsis , maize, rice, and barley. Interestingly, winter‐type pennycress was found to have a higher overall root count, lateral length, and width, compared to the spring‐type pennycress used in the experiment (Griffiths et al., 2023). A similar study in rapeseed analyzed 387 spring and winter germplasm, where winter‐type accessions were found to have a more robust primary and lateral root system (Thomas et al., 2016).…”

“…In addition, significant interactions between genotypes by nitrate conditions were observed for the pennycress accession studied (Griffiths et al., 2023). These research findings emphasize harnessing diverse root phenotypes and modeling the pennycress root system based on the desired environment (Griffiths et al., 2023).…”

“…Griffiths et al. (2023) studied the variation of 24 diverse pennycress lines in response to nitrate nutrition. Although pennycress has a tap root system, Griffiths et al.…”

“…A similar study in rapeseed analyzed 387 spring and winter germplasm, where winter‐type accessions were found to have a more robust primary and lateral root system (Thomas et al., 2016). Three distinct phenotypic responses for nitrate applications were observed exhibiting normal roots in sufficient/excess nitrate, excess root foraging in limited nitrate, and cessation of root growth in critical nitrate levels (Griffiths et al., 2023). In addition, significant interactions between genotypes by nitrate conditions were observed for the pennycress accession studied (Griffiths et al., 2023).…”

“…Three distinct phenotypic responses for nitrate applications were observed exhibiting normal roots in sufficient/excess nitrate, excess root foraging in limited nitrate, and cessation of root growth in critical nitrate levels (Griffiths et al., 2023). In addition, significant interactions between genotypes by nitrate conditions were observed for the pennycress accession studied (Griffiths et al., 2023). These research findings emphasize harnessing diverse root phenotypes and modeling the pennycress root system based on the desired environment (Griffiths et al., 2023).…”