Poly-γ-glutamic acid enhanced drought resistance of maize by improving
photosynthesis and effecting rhizosphere microbial communities
Compared with other abiotic stresses, drought stress is a serious causal
factor leading to crop yield reduction. Poly-γ-glutamic acid (γ-PGA)，as
an environmental friendly biomacromolecule, plays an important role in
plant growth and regulation. In this project, we studied the effect of
exogenous application of γ-PGA on drought resistance of maize (Zea mays.
L) and its mechanism were studied. Drought can significantly inhibit the
growth and development of maize, but the exogenous application of γ-PGA
can apparently increase the dry weight of maize and the contents of ABA,
soluble sugar, proline, and chlorophyll under severe drought stress.
RNAseq study found that γ-PGA may enhance drought resistance of maize by
affecting the expression of the ABA biosynthesis and ABA signal
transduction related genes, photosynthesis-related genes and other
stress-responsive genes, which were also demonstrated by RT-PCR and
promoter motif analysis. The results of diversity and structure analysis
of rhizosphere soil bacterial community showed that γ-PGA could enrich
the plant growth promoting bacteria such as Actinobacteria, Chloroflexi,
Firmicutes, Alphaproteobacteria and Deltaproteobacteria, so as to
improve the drought resistance of maize. This study emphasized the
possibility of using γ-PGA to improve crop drought resistance and soil
environment under drought condition.