GRAS transcription factors emerging regulator in plants growth, development, and multiple stresses.

GRAS transcription factors play multifunctional roles in plant growth, development, and resistance to various biotic and abiotic stresses. The structural and functional features of GRAS TFs have been unveiled in the last two decades. A typical GRAS protein contained a C-terminal GRAS domain with a highly variable N-terminal region. Studies on these TFs increase in numbers and are reported to be involved in various important developmental processes such as flowering, root formation, and stress responses. The GRAS TFs and hormone signaling crosstalk can be implicated in plant development and to stress responses. There are relatively few reports about GRAS TFs roles in plants, and no related reviews have been published. In this review, we summarized the features of GRAS TFs, their targets, and the roles these GRAS TFs playing in plant development and multiple stresses.

Manipulating GA-Related Genes for Cereal Crop Improvement.

The global population is projected to experience a rapid increase in the future, which poses a challenge to global food sustainability. The "Green Revolution" beginning in the 1960s allowed grain yield to reach two billion tons in 2000 due to the introduction of semi-dwarfing genes in cereal crops. Semi-dwarfing genes reduce the gibberellin (GA) signal, leading to short plant stature, which improves the lodging resistance and harvest index under modern fertilization practices. Here, we reviewed the literature on the function of GA in plant growth and development, and the role of GA-related genes in controlling key agronomic traits that contribute to grain yield in cereal crops. We showed that: (1) GA is a significant phytohormone in regulating plant development and reproduction; (2) GA metabolism and GA signalling pathways are two key components in GA-regulated plant growth; (3) GA interacts with other phytohormones manipulating plant development and reproduction; and (4) targeting GA signalling pathways is an effective genetic solution to improve agronomic traits in cereal crops. We suggest that the modification of GA-related genes and the identification of novel alleles without a negative impact on yield and adaptation are significant in cereal crop breeding for plant architecture improvement. We observed that an increasing number of GA-related genes and their mutants have been functionally validated, but only a limited number of GA-related genes have been genetically modified through conventional breeding tools and are widely used in crop breeding successfully. New genome editing technologies, such as the CRISPR/Cas9 system, hold the promise of validating the effectiveness of GA-related genes in crop development and opening a new venue for efficient and accelerated crop breeding.

E3 SUMO ligase AtSIZ1 positively regulates SLY1-mediated GA signalling and plant development.

Gibberellins affect various plant development processes including germination, cell division and elongation, and flowering. A large number of studies have been carried out to address the molecular mechanisms that mediate gibberellin signalling effects on plant growth. However, such studies have been limited to DELLA protein degradation; the regulatory mechanisms controlling how the stability and function of SLEEPY1 (SLY1), a protein that interacts with target DELLA proteins as components of the Skp, Cullin, F-box (SCF)(SLY1) complex, are modulated at the post-translational level have not been addressed. In the present study, we show that the E3 SUMO (small ubiquitin-related modifier) ligase AtSIZ1 regulates gibberellic acid signalling in Arabidopsis species by sumoylating SLY1. SLY1 was less abundant in siz1-2 mutants than in wild-type plants, but the DELLA protein repressor of ga1-3 (RGA) was more abundant in siz1-2 mutants than in wild-type plants. SLY1 also accumulated to a high level in the SUMO protease mutant esd4. Transgenic sly1-13 mutants over-expressing SLY1 were phenotypically similar to wild-type plants; however, sly1-13 plants over-expressing a mutated mSLY1 protein (K122R, a mutation at the sumoylation site) retained the mutant dwarfing phenotype. Over-expression of SLY1 in sly1-13 mutants resulted in a return of RGA levels to wild-type levels, but RGA accumulated to high levels in mutants over-expressing mSLY1. RGA was clearly detected in Arabidopsis co-expressing AtSIZ1 and mSLY1, but not in plants co-expressing AtSIZ1 and SLY1. In addition, sumoylated SLY1 interacted with RGA and SLY1 sumoylation was significantly increased by GA. Taken together, our results indicate that, in Arabidopsis, AtSIZ1 positively controls GA signalling through SLY1 sumoylation.