Tempo of gene regulation in wild and cultivated Vitis species shows coordination between cold deacclimation and budbreak

Authors: KOVALESKI, ALLISON - Cornell University; Londo, Jason

Submitted to: Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/25/2019
Publication Date: 6/25/2019
Citation: Kovaleski, A.P., Londo, J.P. 2019. Tempo of gene regulation in wild and cultivated Vitis species shows coordination between cold deacclimation and budbreak. Plant Science. 287:110178. https://doi.org/10.1016/j.plantsci.2019.110178.
DOI: https://doi.org/10.1016/j.plantsci.2019.110178

Interpretive Summary: Perennial crop species, like grapevine, survive the freezing stress of winter by going dormant. The dormant buds have to be able to detect the changes in winter temperatures in order to know when to gain cold hardiness during very cold temperature drops, and when to lose hardiness as spring approaches. Wild grapevine and cultivated grapevine differ in how fast they are able to lose cold hardiness in the late winter/early spring and this research was conducted to try and determine what the difference is using gene expression data. Dormant grapevine cuttings from two wild species (Vitis riparia and Vitis amurensis) and two cultivated varieties ('Riesling' and 'Cabernet Sauvignon') were collected from the field and placed in a warm growth room to lose cold hardiness. As they lost cold hardiness over several days, bud tissue was collected to examine how gene expression was changing. Vitis riparia and Vitis amurensis lose cold hardiness very quickly compared with the cultivated grapevines. At a gene expression level, we learned that all four grapevines turned on the same gene pathways in response to warm temperatures, but the wild grapevines were faster at every step. Key hormone, cell division, and growth pathways were important during loss of cold hardiness. Because the hormone ABA seemed to play and early role in loss of cold hardiness, we tested if externally applied ABA could halt the loss of cold hardiness. We found that ABA could indeed prevent loss of cold hardiness, and as a later result, also delay budburst. This finding is potentially very important as applications of ABA could be useful in the field to prevent loss of cold hardiness when false springs occur.

Technical Abstract: Dormancy release, loss of cold hardiness and budbreak are critical aspects of the annual cycle of deciduous perennial plants. Molecular control of these processes is not fully understood, and genotypic variation may be important for climate adaptation. Single-node cuttings from wild (Vitis amurensis, V. riparia) and cultivated Vitis genotypes (V. vinifera 'Cabernet Sauvignon', 'Riesling') were collected from the field during winter and placed under forcing conditions. Cold hardiness was measured daily, and buds were collected for RNA-Seq until budbreak. Field-collected single-node cuttings of 'Riesling' were treated with abscisic acid (ABA), and cold hardiness and budbreak at 7 °C were tracked. Wild Vitis genotypes had faster deacclimation and budbreak than V. vinifera. Temperature-sensing related genes were quickly and synchronously differentially expressed in all genotypes. ABA synthesis was down-regulated in all genotypes, and exogenous ABA prevented deacclimation. Ethylene- and oxidative stress-related genes were transiently up-regulated. Growth-related genes were up-regulated and showed staggering similar to deacclimation and budbreak of the four genotypes. The gene expression cascade that occurs during deacclimation and budburst phenology of fast (wild) and slow (cultivated) grapevines appears coordinated and temporally conserved. This may extend to other temperate woody species and suggest constraints on identification of process-specific keystone genes.