Lateral roots (LRs) are an important organ for water and nutrient uptake from soil. Thus, control of LR formation is crucial in the adaptation of plant growth to environmental conditions. However, the underlying mechanism controlling LR formation in response to external factors has remained largely unknown. Here, we found that LR formation was inhibited by DNA damage. Treatment with zeocin, which causes DNA double-strand breaks, up-regulated several DNA repair genes in the LR primordium (LRP) through the signaling pathway mediated by the transcription factor SUPPRESSOR OF GAMMA RESPONSE 1 (SOG1). Cell division was severely inhibited in the LRP of zeocin-treated sog1-1 mutant, which in turn inhibited LR formation. This result suggests that SOG1-mediated maintenance of genome integrity is crucial for proper cell division during LRP development. Furthermore, zeocin induced several cytokinin biosynthesis genes in a SOG1-dependent manner, thereby activating cytokinin signaling in the LRP. LR formation was less inhibited by zeocin in mutants defective in cytokinin biosynthesis or signaling, suggesting that elevated cytokinin signaling is crucial for the inhibition of LR formation in response to DNA damage. We conclude that SOG1 regulates DNA repair and cytokinin signaling separately and plays a key role in controlling LR formation under genotoxic stress.

No abstract

Biological diversity can make a significant contribution to reducing greenhouse gases in the atmosphere. Trees form an essential part of the functioning of the terrestrial biosphere, especially in the carbon cycle. Yet, tree photosynthesis is far less studied than crop photosynthesis. This research aims to assess CO2 absorption-related physiological characteristics of selected tropical lowland trees that are curated in Cibinong Science Center-Botanical Garden (CSC-BG) Indonesia for revegetation prospecting. CO2 absorption, stomatal conductance, and transpiration were measured using an infrared gas analyzer photosynthesis system. Meanwhile, leaf chlorophyll content was estimated using a SPAD chlorophyll-meter. CO2 absorption rate ranged from 3.42 to 20 μmol m−2 s−1. The highest rate was observed in Teijsmanniodendron bogoriense followed by Tectona grandis (19.67 μmol m−2 s−1). The rate of transpiration ranged from 4.7 μmol m−2 s−1 to 7.82 μmol m−2 s−1. Diospyros discolor was the highest, followed by T. grandis (7.65 μmol m−2 s−1). CO2 absorption and rate of transpiration were positively correlated to stomatal conductance. In contrast, the CO2 absorption and chlorophyll content were very weakly correlated. The stomatal conductance ranged from 0.14 to 0.54 μmol m−2 s−1, with that of T. grandis was the highest, followed by Erythrina crista-galli (0.53 μmol m−2 s−1), whereas the chlorophyll content ranged from 31 up to 78.43 SPAD.