Abstract
Tetraploidy modifies root anatomy which may lead to differentiated capacity to uptake and transport mineral elements. This work provides insights into physiological and molecular characters involved in boron (B) toxicity responses in diploid (2x) and tetraploid (4x) plants of Carrizo citrange (Citrus sinensis L. Osb. × Poncirus trifoliata L. Raf.), a widely used citrus rootstock. With B excess, 2x plants accumulated more B in leaves than 4x plants, which accounted for their higher B uptake and root-to-shoot transport rates. Ploidy did not modify the expression of membrane transporters NIP5 and BOR1 in roots. The cellular allocation of B excess differed between ploidy levels in the soluble fraction, which was lower in 4x leaves, while cell wall-linked B was similar in 2x and 4x genotypes. This correlates with the increased damage and stunted growth recorded in the 2x plants. The 4x roots were found to have fewer root tips, shorter specific root length, longer diameter, thicker exodermis and earlier tissue maturation in root tips, where the Casparian strip was detected at a shorter distance from the root apex than in the 2x roots. The results presented herein suggest that the root anatomical characters of the 4x plants play a key role in their lower B uptake capacity and root-to-shoot transport.HighlightsTetraploidy enhances B excess tolerance in citrange CarrizoExpression of NIP5 and BOR1 transporters and cell wall-bounded B are similar between ploidiesB tolerance is attributed to root anatomical modifications induced by genome duplicationThe rootstock 4x citrange carrizo may prevent citrus trees from B excess.
Highlights
Boron (B) is an essential micronutrient required in major physiological functions for normal higher plant growth and development (Brown et al, 2002), as it participates in cell wall structure formation through the borate-diol bonding of two rhamnogalacturonan II molecules (O‘Neill et al, 2004; Funakawa and Miwa, 2015)
Some 4x citrus could be used as rootstocks since the physiology of citrus trees is deeply influenced by root characteristics, which play a key role in the capacity to uptake and transport mineral elements
Citrus rootstocks differ in terms of their ability to exclude toxic compounds from being accumulated in leaves; the use of tolerant rootstocks is considered a suitable system to agronomically manage toxicity problems given the excess of some elements (Walker et al, 1984)
Summary
Boron (B) is an essential micronutrient required in major physiological functions for normal higher plant growth and development (Brown et al, 2002), as it participates in cell wall structure formation through the borate-diol bonding of two rhamnogalacturonan II molecules (O‘Neill et al, 2004; Funakawa and Miwa, 2015). When soil moisture is available, Lpr represents the major limiting factor for water and solute uptake The differences in this parameter between rootstocks can result in restricted transport to shoots, which influences the leaf water status and, in turn, plant growth and physiological responses. Some 4x citrus could be used as rootstocks since the physiology of citrus trees is deeply influenced by root characteristics, which play a key role in the capacity to uptake and transport mineral elements In this way, citrus rootstocks differ in terms of their ability to exclude toxic compounds from being accumulated in leaves; the use of tolerant rootstocks is considered a suitable system to agronomically manage toxicity problems given the excess of some elements (Walker et al, 1984). Citranges are considered moderately sensitive to B toxicity (Grattan et al, 2015)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
