Functional and Genetic Analysis of Plant Transcription Factors Involved in the Plant Growth Under Various Environmental Conditions

Abstract

Arabidopsis serves as a model system for the plant molecular biology. Many biotic and abiotic factors affect plant growth from seed germination to mature plant growth. External factors studied in our research include nutrients and salinity. Phytohormone pathways interact with glucose and salt stress signaling pathways to affect plant growth. Abscisic acid (ABA) and gibberellic acid (GA) are two important phytohormones that impact the plant development. Exogenous glucose and salt stress delay seed germination in Arabidopsis thaliana not only in wild type (WT) but also in a number of mutants in hormone signaling pathways. Our study demonstrates that the ABA

Insensitive 3 (ABI3) gene in the ABA signaling pathway and the RGA-like 2 (RGL2) genes in the GA signaling pathways playing important roles in the glucose-induced delay and salt inhibition of seed germination. Transcription of the ABI3 and RGL2 genes is up-regulated by glucose and salt. The study also demonstrates that several genes in ABA and GA signaling pathways have essential functions during early and later seedling development. This study suggests that different genes in ABA and GA signaling pathways are involved at different developmental stages under stress condition and glucose treatment. The possible crosstalk between different hormone signaling pathways exists under salt and osmotic stress conditions. Three genes in the GRAS family, SCARECROW (SCR), SHORT ROOT (SHR) and SCARECROW-LIKE 3 (SCL3) are involved in the salt-induced inhibition of seedling development. Transcription of the SCR and SHR genes is up-regulated by salt. There are differences in stress tolerance between genotypes or differences in stress tolerance at different developmental stages within a single genotype. This study also demonstrated the interaction among GRAS family genes (SCR, SHR and SCL3) and components (SOS1, SOS2 and SOS3) in Salt overly sensitive (SOS) signaling pathway. The result indicated that SCR and SHR may play important roles in the salt-induced inhibition of seedling development via regulating transcription levels of SOS1, 2 and 3 in SOS signaling pathway.