Identification and expression of the Di19 gene family in response to abiotic stress in common bean (Phaseolus vulgaris L.).

Drought-induced 19 (Di19) protein plays critical biological functions in response to adversity as well as in plant growth and development. Exploring the role and mechanism of Di19 in abiotic stress responses is of great significance for improving plant tolerance. In this study, six Di19 genes were identified in the common bean (Phaseolus vulgaris L.), which were mainly derived from segmental duplications. These genes share conserved exon/intron structures and were classified into three subfamilies based on their phylogenetic relationships. The composition and arrangement of conserved motifs were consistent with their phylogenetic relationships. Many hormone- and stress-responsive elements were distributed in the promoters region of PvDi19 genes. Variations in histidine residues in the Cys2/His2 (C2H2) zinc-finger domains resulted in an atypical tertiary structure of PvDi19-5. Gene expression analysis showed rapid induction of PvDi19-1 in roots by 10% PEG treatment, and PvDi19-2 in leaves by 20% PEG treatment, respectively. Most PvDi19s exhibited insensitivity to saline-alkali stress, except for PvDi19-6, which was notably induced during later stages of treatment. The most common bean Di19 genes were inhibited or not regulated by cadmium stress, but the expression of PvDi19-6 in roots was significantly upregulated when subjected to lower concentrations of cadmium (5 mmol). Moreover, Di19s exhibited greater sensitivity to severe cold stress (6°C). These findings enhance our understanding of the role of PvDi19s in common bean abiotic stress responses and provide a basis for future genetic enhancements in common bean stress tolerance.

nirS-type denitrifying bacterial communities in relation to soil physicochemical conditions and soil depths of two montane riparian meadows in North China.

Mountain riparian zones are excellent buffers for protecting aquatic ecosystems from nutrient runoff in nitrogen deposition processes due to fertilization and manure. Denitrification is a critical process for transferring soil N to the atmosphere. Denitrifying bacterial communities in soil are indicative of the soil quality of a functional ecosystem. We investigated the effects of physicochemical properties of soil on the diversity and activity of denitrifiers in the top-soil and sub-soil of two typical montane riparian meadows: a multi-colored and a flood-plain meadow. Illumina MiSeq 2500 sequencing of nirS showed that the multi-colored meadow had greater diversity and abundance of nirS-type denitrifiers than the flood-plain meadow and that the total N content, ammonium content, and denitrification enzyme activity (DEA) in soil differed significantly between the two types of meadows. The abundances of dominant denitrifiers at phylum and genus levels showed different responses to the two soil layers of the two meadow types. In top-soils, the highest abundance of Firmicutes was recorded in the multi-colored meadow, while in the flood-plain meadow, there was the highest abundance of Proteobacteria. The Actinobacteria abundance was the highest in top-soil and sub-soil of the flood-plain meadow. The abundance of Chloroflexi was the highest in top-soil of the flood-plain meadow and in sub-soil of the multi-colored meadow. The diversity of denitrifying bacteria was strongly influenced by variations of soil properties down the soil profile. Spearman's rank correlation analyses showed that the diversity and community composition of denitrifying bacteria were strongly associated with most of the soil properties. Therefore, physicochemical soil properties, and particularly the organic carbon, nitrate, and ammonium contents, influence the diversity and abundance of denitrifiers in soil.

Sowing Methods Influence Soil Bacterial Diversity and Community Composition in a Winter Wheat-Summer Maize Rotation System on the Loess Plateau.

Soil bacterial diversity and community composition are crucial for soil health and plant growth, and their dynamics in response to agronomic practices are poorly understood. The aim of this study was to investigate the response of soil bacterial community structure to the changes of sowing methods, soil depth and distance to roots in a winter wheat-summer maize crop rotation system on the Loess Plateau in china (35°17'38''N, 111°40'24''E). The experiment was laid out as completely randomized block design with three replications. Sowing methods trialed were: traditional sowing (TS), film-mulched ridge and furrow sowing (FMR&F), wide ridge and narrow furrow sowing (WR&NF) and unplanted control (CK). The result showed that the WR&NF sowing method treatment significantly decreased soil bacterial diversity (Chao 1 and Shannon indices) compared to the TS and FMR&F treatment, but increased abundance of beneficial bacteria such as genera Bacillus and Pseudomonas compared to the TS treatment. These genera showed a stronger correlation with soil properties and contributed to the soil nutrient cycling and crop productivity. Bacillus, Pseudomonas, Nevskia, and Lactococcus were the keystone genera in this winter wheat-summer maize rotation system on the Loess Plateau. Strong correlations between changes in soil properties and soil bacterial diversity and abundance were identified. In summary, we suggest that the WR&NF treatment, as a no-mulching film and no-deep tillage sowing method, would be the most suitable sowing technique in the winter wheat-summer maize rotation on Loess soil.