Lateral root development differs between main and secondary roots and depends on the ecotype

Abstract

Root architecture depends on the development of the main root and also on the number and density of lateral roots. Most molecular knowledge about the development of lateral roots was acquired studying primary roots, and it was implied that high order roots follow the same pattern. Recently, we informed that AtHB23 is differentially regulated in primary and secondary roots. Here we show that LBD16, a target of AtHB23, also is differentially regulated; it is expressed in the tip of secondary and tertiary roots but not in primary ones. Moreover, the key hormone auxin exhibits a different distribution pattern in secondary and tertiary roots, according to the reporter DR5. Finally, we show that in Col 0 and Ler ecotypes development of secondary and tertiary roots exhibits significant variations. Altogether, we can conclude that different genetic programs govern secondary and tertiary roots development and such processes are dependent on the Arabidopsis genotype.

The transcription factor AtHB23 modulates starch turnover for root development and plant survival under salinity

“…bp shorter than the one previously assessed (Perotti et al, 2019(Perotti et al, , 2020 and Fig. S1), our results suggest that the deleted region might include a repressor box.…”

“…Previously, it was shown that in normal growth conditions, the knock-down of AtHB23 provoked an enhancement in LR initiation. This TF is upregulated by ARF7/19, induced the expression of LAX3 and repressed that of LBD16 in LR, and, importantly, this genetic program differed between second and third-order roots (Perotti et al, 2019(Perotti et al, , 2020. Under salinity stress, plants with altered levels of AtHB23 exhibited significant changes in root architecture.…”

“…Transgenic plants bearing the promoters of LAX3 and LBD16 fused to the GUS reporter gene were analyzed in control conditions and after treatments with 75 mM NaCl in the main, secondary, and tertiary roots. That is because the modulation of these genes was found to be dependent on the root order (Perotti et al, 2020). LAX3 was expressed in the root tip of the main, lateral, and third order roots in 14-day-old seedlings (Fig.…”

“…AtHB23 is a transcription factor belonging to the HD-Zip I subfamily, and it was described as a modulator of LR initiation through the direct regulation of LAX3 and LBD16. This gene is regulated by ARF7/19 (Perotti et al, 2019(Perotti et al, , 2020. , 2008), and because HD-Zip I TFs were associated with abiotic stress (Perotti et al, 2017), we wondered whether AtHB23…”

A complex tissue-specific interplay between the Arabidopsis transcription factors AtMYB68, AtHB23, and AtPHL1 modulates primary and lateral root development and adaptation to salinity

“…BD-HY5 + AD-STO and pDBLeu + pAD-502 were used as positive and negative controls, respectively. AtHB23ΔAHA: the C-terminal AHA domain was removed (Capella et al, 2014) AtMYB68 and AtPHL1 coexpress with AtHB23 in specific tissues and developmental stages of root development To test the functional sense of the interaction between these three TF, we first investigated the expression patterns of AtMYB68 and AtPHL1 in roots, the organ in which AtHB23 was deeply investigated, associated with developmental and salinity responses (Perotti et al, 2019(Perotti et al, , 2020(Perotti et al, , and 2022. For this purpose, we used 8-day-old transgenic plants carrying the constructs prAtMYB68:GUS and prAtPHL1:GUS.…”