CRF2 and CRF3, encoding APETALA2 transcription factors, play an important role in lateral root initiation and root system architecture changes under cold stress

Several members of the Lateral Organ Boundaries Domain (LBD)/Asymmetric Leaves2-Like (ASL) gene family have been identified to play important roles in Arabidopsis (Arabidopsis thaliana) lateral root (LR) development during auxin response, but their functional relationship with auxin transporters has not been established yet. Here, we show that the AUXIN1 (AUX1) and LIKE-AUXIN3 (LAX3) auxin influx carriers are required for auxin signaling that activates LBD16/ASL18 and LBD18/ASL20 to control LR development. The lax3 mutant phenotype was not significantly enhanced when combined with lbd16 or lbd18. However, LBD18 overexpression could rescue the defects in LR emergence in lax3 with concomitant expression of the LBD18 target genes. Genetic and gene expression analyses indicated that LBD16 and LBD18 act with AUX1 to regulate LR initiation and LR primordium development, and that AUX1 and LAX3 are needed for auxin-responsive expression of LBD16 and LBD18. LBD18:SUPERMAN REPRESSIVE DOMAIN X in the lbd18 mutant inhibited LR initiation and LR primordium development in response to a gravitropic stimulus and suppressed promoter activities of the cell cycle genes Cyclin-Dependent Kinase A1;1 and CYCLINB1;1. Taken together, these results suggest that LBD16 and LBD18 are important regulators of LR initiation and development downstream of AUX1 and LAX3.

The leucine-zipper-like coiled-coil motif is crucial for the homodimerization of LBD16 and LBD18 and for the transcriptional regulation and biological function

Yurim Kim, Myoung-Goo Choi, Han-Yong Jeong, Jinhee Park, Yurim Kim, Go Eun Lee, Sukjin Kim, Jeong-Heui Lee, and Chuloh Cho. Korean J. Breed. Sci. 2025;57:103-30. https://doi.org/10.9787/KJBS.2025.57.2.103

High temperature can impair grain development and storage compound accumulation during wheat grain filling, with responses depending on stress intensity, timing, duration, and cultivar. In this study, Saekeumkang and Hwanggeumal were selected from among major Korean wheat cultivars because they differ in grain quality- and starch-related characteristics, providing a basis for comparing cultivar-specific responses to heat stress during grain filling. Plants were exposed to 25/15, 35/25, and 40/30 °C (day/night) temperature regimes for 5 d beginning at 10 or 20 days after heading (DAH), and changes in grain morphology, endosperm and embryo development, 100-grain weight, protein concentration, and storage-related gene expression were evaluated. High temperature altered grain developmental traits and generally reduced 100-grain weight, while the magnitude of these effects differed between cultivars and treatment stages. Grain protein concentration and the expression of starch- and storage protein-related genes also showed cultivar- and stage-dependent responses. In a separate RNA-seq experiment initiated at 10 DAH, plants were exposed to the temperature treatments for either 5 or 10 d, and transcriptomic analysis revealed that heat intensity and exposure duration affected both the number and functional characteristics of differentially expressed genes, particularly those associated with protein folding and quality control, chromatin-related processes, and carbohydrate metabolism. These results indicate that heat responses during wheat grain filling are jointly influenced by developmental stage, exposure duration, and cultivar-specific molecular regulation.