Exopolysaccharides-EPS are long-chain biopolymer with branched, recurring unit of sugars and non-carbohydrate constituents connected to exterior of cells. Rhizobial, a legume nodulating organism is capable of producing EPS. This study investigated the characteristics’ of some Rhizobium EPS and their effects in shelf life extension of some Musa spp. Rhizobial-EPS was produced using yeast extract mineral medium purified by standard methods. The EPS was characterized to determine functional group, thermal stability, chemical compounds and the monosaccharide component using Fourier Transform Infra-red, Spectroscopy, thermogravimetric Analysis (TGA), Gas Chromatography–Mass Spectrometry and HPLC and their bio-preservative property on post-harvest quality of plantain and different banana was done. The Rhizobial-EPS functional groups were hydroxyl, carboxyl, amine, methyl and ethers associated with polysaccharides. Pentadecanoic acid, octadecanoic acid, oleic acid and heptacosanoic acid, and varied concentration of monosaccharides were detected in the exopolysaccharides. The TGA of the EPS shows a constant loss in weight with two quasi-sharp alterations and almost steady plateau. The EPS coated samples had the lowest weight loss across the samples and as such edible coating was effective in delaying weight loss. The weight loss of Musa paradisiaca (plantain) coated with (EPSA obtained from USDA 110), (EPSB USDA 532C) and (EPSC S2) at the first day were 314 and 314.5g. The initial weight loss of coated and uncoated Musa sp. (Apple Banana), Musa acuminata (Lady Finger), and Musa balbisiana (Cooking Banana), ranged from 72 – 72.7g, 96 – 97g and 95 – 98g respectively. The total sugar of EPS Coated Musa sp. ranges from 0.381 – 0.528mg/L, 0.392 – 0.576 mg/L and 0.41 – 0.598 mg/L at days 1, 2 and 3 respectively. The highest Titratable acidity and pH was observed in EPS coated sample. The results obtained from this study proves that EPS solution is a valuable product for fruit preservation and viable for commercial applications.

Legume-rhizobial symbiosis leads to to the formation of root nodules, where rhizobia reside and develop into bacteroids to reduce nitrogen into ammonium for plant growth, which leaves an opening question as how plant immunity is attenuated in nodules in the presence of large number of foreign bacteria. In Medicago truncatula, mutation in NAD1 (Nodules with Activated Defense 1) only produces necrotic nodules with overactivated immunity, indicating NAD1 is an indispensable component required for suppressing immunity in nodules. In this study, a dual RNA-seq transcriptomic technology was performed to extensively analyze gene expressions in nad1-1 mutant nodules. We indenifited 89 DEGs in symbiotic nitrogen fixation and 89 DEGs in immunity in Medicago truncatula at 10 dpi. Simultaneously, we indenifited 27 DEGs in fix and nif genes in Sinorhizobium meliloti. Then we identified 56 DEGs related to stress, including ROS, NO, and NCR, most of which were upregulated in Sinorhizobium meliloti. Our analyses of nitrogen fixation-defective plant nad1-1 mutants with overactivated defense indicate that host use plant immunity to control massive bacterial colonization during early and late symbiotic stages. Our findings provide insight into the function of NAD1 in improvement or inhibition of plant immune response to maintain symbiosis during rhizobial endosymbiosis.

: To improve the efficiency of rhizobial inoculation operations and address the current situation of rhizobial inoculation being labor-intensive, a spraying and control system for variable rate application (VRA) of liquid rhizobia was developed. The system can accurately regulate the spraying rate of liquid rhizobia according to the desired rate of rhizobia by incremental Proportional Integral Derivative (PID) closed-loop control algorithm, making it particularly suitable for precise spraying with small amounts. In the laboratory experiment of precise flow control, variation coefficient of spraying nozzle from 0.10 MP to 0.20 MP pressure were no more than 1.2%. A clear linear relationship was observed between the spraying rate and pressure. The maximum response time was 1.93 seconds, while the average response time was 1.62 seconds when controlling the spraying system for small amounts. Field trial was conducted in Heilongjiang Agricultural Xianghe Farm of China. Average seeds number and 100-seed weight of soybean plant with rhizobia inoculation treatment were better than control group, and average yield of spraying liquid rhizobia agent with full base fertilizer increased by 232.5 kg/hm2, representing a significant 7.4% improvement over the control group. The results of these trails clearly showed the positive effect of the spraying and control system for liquid rhizobial inoculation, which has superior to existing inoculation manners, and provides an important technical support for the widespread adoption of rhizobia technology.

Paenibacillus sp. tmac-D7 was isolated from coastline growing Trifolium macraei (double-head clover) root nodules from Bodega Bay, California. The draft genome is 5,567,337 bp with a G+C% of 52.4%, an N50 of 114,261 bp, and 5,282 predicted protein-coding genes. Paenibacillus, while found in many other environments, is frequently isolated from root nodules, with many acting as plant pathogen antagonists. Paenibacillus sp. tmac-D7 is the first genome of a non-rhizobial endophyte isolate from wild Trifolium macraei (double-head clover).