Synthetic Polyploidy in Grafted Crops

Abstract

Synthetic polyploids have been extensively studied for breeding in the last decade. However, the use of such genotypes at the agronomical level is still limited. Polyploidization is known to modify certain plant phenotypes, while leaving most of the fundamental characteristics apparently untouched. For this reason, polyploid breeding can be very useful for improving specific traits of crop varieties, such as quality, yield, or environmental adaptation. Nevertheless, the mechanisms that underlie polyploidy-induced novelty remain poorly understood. Ploidy-induced phenotypes might also include some undesired effects that need to be considered. In the case of grafted or composite crops, benefits can be provided both by the rootstock's adaptation to the soil conditions and by the scion's excellent yield and quality. Thus, grafted crops provide an extraordinary opportunity to exploit artificial polyploidy, as the effects can be independently applied and explored at the root and/or scion level, increasing the chances of finding successful combinations. The use of synthetic tetraploid (4x) rootstocks may enhance adaptation to biotic and abiotic stresses in perennial crops such as apple or citrus. However, their use in commercial production is still very limited. Here, we will review the current and prospective use of artificial polyploidy for rootstock and scion improvement and the implications of their combination. The aim is to provide insight into the methods used to generate and select artificial polyploids and their limitations, the effects of polyploidy on crop phenotype (anatomy, function, quality, yield, and adaptation to stresses) and their potential agronomic relevance as scions or rootstocks in the context of climate change.

Wild Olive Genotypes as a Valuable Source of Resistance to Defoliating Verticillium dahliae

“…cerasiformis ). These genotypes were classified as susceptible (CER3) or extremely susceptible (MAR1, CER1) to V. dahliae despite being polyploid genotypes, a characteristic previously related to resistance to abiotic and biotic stress in plants ( Sattler et al, 2016 ; Ruiz et al, 2020 ; Russo et al, 2020 ).…”

Changes In Ploidy Affect Vascular Allometry And Hydraulic Function In Trees

“…Additionally, tetraploid leaves showed a higher elastic modulus, a parameter that describes the relationship between turgor and cell volume and reflects foliar cell rigidity (Barlett et al, 2012;Trifilo et al, 2016;Nadal et al, 2019). If stomatal closure is linked to the turgor loss point, a higher elastic modulus may be useful during periods of water scarcity, extending the time in which water is retained in the leaves compared with diploids, as observed, for example, in polyploid rootstocks (for a review see Ruiz et al, 2020). Pressurevolume relationships have been extensively used in the study of leaf and stem hydraulic properties of woody species (Sack et al 2003;Nadal et al, 2019), but rarely comparing conspecific individuals with different ploidies, such as in seedlings of Betula, which also exhibited a higher water content at turgor loss for tetraploids (Li et al, 1996).…”

Specific Physiological and Anatomical Traits Associated With Polyploidy and Better Detoxification Processes Contribute to Improved Huanglongbing Tolerance of the Persian Lime Compared With the Mexican Lime

“…Polyploidy is often associated with a wide range of morphological and physiological changes that may be advantageous under harsh environments (Brochmann et al, 2004). Indeed, several investigations have shown that polyploidization improves stress tolerance under adverse environmental conditions (for review, see Ruiz et al, 2020), which remains true in woody grafted plant species (Khalid et al, 2020;Ruiz et al, 2020). Most citrus are diploid, and several citrus species produce apomictic seeds favoring the natural occurrence of polyploidy among seedlings (Aleza et al, 2011).…”