Abstract Detail

Crops and Wild Relatives

Fleishman, Suzanne [1], Mélanie, Massonnet [2], Dario, Cantu [3], Eissenstat, David [4], Michela, Centinari [5].

Direct comparisons of grapevine rootstock gene expression expand insights into root responses to N competition.

Grapevines (Vitis spp.) have deep and plastic root systems that are highly responsive to variations in soil resource availability. This responsiveness can vary between rootstocks, which grapevines grown for production are frequently grafted onto for a wide variety of benefits, including management of aboveground growth. Thus far, studies into the differences in rootstock responses to resource stress have been limited by the high variability and intensive nature of root research. An increasingly important tool to clarify rootstock differences is gene expression analysis, which only recently has had rootstock-specific transcriptomes available. In 2020 and at a long-term field site in Pennsylvania, USA, we implemented an experiment to clarify the root-level responses of two rootstocks to N competition from a grass (Festuca rubra) using physiological and transcriptomic approaches. The two rootstocks examined were: 1) Vitis riparia (LV), a species native to North America and considered to provide “low vigor” to the scion, and 2) 101-14 Mgt. (MV), a cross of Vitis riparia and another North American species (Vitis riparia x Vitis rupestris) considered to provide “medium vigor” to the scion. Observations of roots up to 1 meter depth were completed with root boxes and included both standard physiological measurements and root gene expression (assessed with RNA-seq analysis).
Overall, the physiological measurements in the study found little evidence of varying responses of the rootstocks to N competition. Previous evidence from soil cores at the site (2019) indicated that the root distributions of the two rootstocks may have responded differently to competition, with the MV rootstock compensating with increased root growth at a middle soil depth (20-40 cm), compared to compensation at a deep soil depth (60-100 cm) by the LV rootstock (p<0.10). Observations from the root boxes in 2020, however, indicated that new root growth did not vary between rootstocks, and both responded similarly to the competition by decreasing growth 29% at shallow depths (< 33 cm) and increasing growth 15% at deeper depths (67-100 cm). Preliminary evidence of N-uptake rates also suggests rootstocks may vary in N-uptake rates at a mid-depth (34-66 cm) but respond similarly to competition by increasing the concentration of N recently taken up in roots (22%; p<0.10).
The responses of the MV and LV rootstocks to N competition was further assessed with RNA-seq analysis. First, N-uptake genes (NRT and NPF gene families) were identified among the predicted proteomes of the two rootstocks based on homology with Arabidopsis thaliana. We found that the N-uptake gene families (NRT and NPF gene families) tend to be highly conserved between Arabidopsis thaliana and Vitis spp. These homologous genes for the two rootstocks were then directly compared to one another to clarify differing responses to competition. Preliminary results suggest that several N-uptake genes were differentially expressed in response to N competition, in a highly depth-dependent manner. On the whole, this work demonstrates how rootstock-specific transcriptomic approaches can expand insights into N-uptake responses beyond physiological observations alone.

1 - The Pennsylvania State University, Plant Science/Ecosystem Science and Management, 220 Forest Resources Building, University Park, PA, 16802, USA
2 - UC Davis, Viticulture and Enology, Davis, California, USA
3 - UC Davis, Viticulture and Enology, Davis, CA, USA
4 - The Pennsylvania State University, Ecosystem Science and Management, University Park, PA, 16802, USA
5 - The Pennsylvania State University, Plant Science, University Park, PA, 16802, USA

Keywords:
Rootstock
Competition
Nutrient
Vitis
Nitrogen
gene expression.

Presentation Type: Oral Paper
Number: CWR1005
Abstract ID:870
Candidate for Awards:None