Root growth analysis in PSARK::IPT wheat transgenic plants upon cadmium exposure

A BEZNEC; MP BENAVIDES; D LEWI; SM GALLEGO; AE BOSSIO; NM GOMEZ MANSUR

Buenos Aires

Congreso; Reunión Conjunta de Sociedades de Biociencias; 2017

Sociedades de Biociencias

Adverse environmental conditions are closely associated to plantgrowth inhibition. Plant hormones play an important role in the adaptationto a stressful environment. In this context, engineering cytokinin(CK) metabolism is described as a prospective way to improvecrop plants adaptation to adverse growth conditions. Transgenicplants expressing the isopentenyltransferase (IPT) gene, a key enzymein cytokinin biosynthesis, placed under the control of PSARKpromoter have resulted promising for maintaining steady state CKlevel higher than normal concentration during stress, but not highenough to impinge in developmental processes. Herein, we studiedthe postembryonic wheat root response to Cd stress in wild type(PIF) and in Psark:IPT transgenic (TR4) Triticum aestivum L plants.Twenty seeds were placed in flasks with 30 mL of distilled (control)or containing 10 μM CdCl2 (PIFCd and TR4Cd) and incubated at24 ± 2°C in darkness for 72 h. Despite Cd treatment significantlydecreased root length in both genotypes, statistically significantinteraction was detected between genotypes and Cd treatment.This result was supported by root biomass determination wherePIF plants were more affected by Cd than TR4 ones. The metaldecreased transcripts accumulation of genes related to the cell cycleG1/S transition (rdr, mcm2), but up-regulated genes related to cellexpansion (TaExpA8, TaExpB8, TaExpA6 and TaExpB10) in the rootapical meristem (RAM). Interestingly statistical analysis showed thatthe effect in expansin transcripts level was genotype-dependent, regardlessof the treatment. Cadmium hastened cells displacementfrom the cell division zone to elongation/differentiation zone, resultingin a shortened meristem in PIF plants. These results indicatedthat Psark:IPT plants have a greater ability to sustain embryo rootelongation under Cd stress. More studies are necessary to evaluatethe importance of the RAM transition zone as an oscillatoryzone that connects root growth and development with environmentalcues.Keys words: WHEAT, CADMIUM, ABIOTIC STRESS, CYTOKININ