Inherent and Stress-Induced Responses of Fine Root Morphology and Anatomy in Commercial Grapevine Rootstocks with Contrasting Drought Resistance.

Idan Reingwirtz,Italo F Cuneo,Andrew J Mcelrone,M Andrew Walker,Thorsten Knipfer,Jake Uretsky,Clarissa Reyes

doi:10.3390/plants10061121

Abstract

Some grapevine rootstocks perform better than others during and after drought events, yet it is not clear how inherent and stress-induced differences in root morphology and anatomy along the length of fine roots are involved in these responses. Using a variety of growing conditions and plant materials, we observed significant differences in root diameter, specific root length (SRL) and root diameter distribution between two commonly used commercial grapevine rootstocks: Richter 110 (110R; drought resistant) and Millardet et de Grasset 101-14 (101-14Mgt; drought sensitive). The 110R consistently showed greater root diameters with smaller SRL and proportion of root length comprised of fine lateral roots. The 110R also exhibited significantly greater distance from tip to nearest lateral, longer white root length, and larger proportion of root length that is white under drought stress. Mapping of fine root cortical lacunae showed similar patterns between the rootstocks; mechanical failure of cortical cells was common in the maturation zone, limited near the root tip, and increased with drought stress for both genotypes; however, lacuna formed under wetter soil conditions in 110R. Results suggest that drought resistance in grapevine rootstocks is associated with thick, limitedly branched roots with a larger proportion of white-functional roots that tend to form lacuna under more mild water deficit, all of which likely favor continued resource acquisition at depth.

Highlights

Rootstocks are utilized in the production of a wide range of perennial and annual crop species to mitigate against deleterious biotic and abiotic factors and promote beneficial horticultural traits [1,2]
Generalizations of root function are made based on diameter, there is high variance in absolute diameter among taxa, and functionality and lifespan of individual roots are often related to their developmental stage and relative position within the root system [15,16]
For both herbaceous cuttings grown in the greenhouse and dormant woody cuttings grown in the field, mean root diameters were consistently larger for 110R compared to those of 101-14Mgt (p < 0.001 for both greenhouse and field grown vines (Table 1))

Summary

Introduction

Rootstocks are utilized in the production of a wide range of perennial and annual crop species to mitigate against deleterious biotic and abiotic factors and promote beneficial horticultural traits [1,2]. Characterizing morphological and anatomical traits related to drought resistance in grapevine roots could facilitate more rapid germplasm screening for rootstock breeding. Water flows preferentially through unsuberized fine roots [6,8,9] compared to suberized coarse roots with low radial hydraulic conductivity [6,10,11]. In grapes, these two broad classes correspond with young lateral roots and the perennial roots from which they emerge [12]. Several orders of perennial lateral roots can develop from these primary roots, acting as scaffolding for the short-lived fine roots that are so critical in resource acquisition [13]

Methods

Results

Conclusion