Reconnoitering the capabilities of nodule endophytic Pantoea dispersa for improved nodulation and grain yield of chickpea (Cicer arietinum L.).

Microorganisms belonging to root and soil provide a wide range of services and benefits to the plant by promoting plant growth and controlling phytopathogens. This study aimed to isolate endophytic bacteria from the root nodules of chickpea (Cicer arietinum L.) and determine their potential in improving plant growth. A total of nineteen different bacterial morphotypes were isolated from root nodules of chickpea and characterized in vitro for plant growth promotion abilities. All bacterial isolates were able to produce indole acetic acid at varying levels, out of which MCA19 was screened as the most efficient indole acetic acid producer (10.25 µg mL-1). MCA8, MCA9, MCA10, MCA11, MCA16, MCA17 and MCA19 were positive for phosphate solubilization, out of which MCA9 was best phosphate solubilizer (18.8 µg mL-1). All bacterial strains showed varying ability to grow on nitrogen-free media. Hydrogen cyanide, pectinase, and cellulase production ability were also observed in isolates, in which MCA9, MCA12, MCA17 and MCA19 were found best. Based on in vitro testing, five isolates MCA2, MCA9, MCA11, MCA17 and MCA19 were selected for further studies. Bacterial isolates MCA9, MCA11, MCA17 and MCA19 were identified by 16S rRNA gene sequence analysis as Pantoea dispersa while MCA2 as Rhizobium pusense. This is the first report on the existence of Pantoea dispersa in the root nodules of chickpea. In pot experiment, a maximum increase of 30% was recorded in plant dry weight upon the application of MCA19. Under field conditions, bacterial isolates, MCA2, MCA11 and MCA19 significantly enhanced nodulation and yield parameters of chickpea, compared to control. Pantoea dispersa MCA19 displayed the highest plant growth-promoting potential by increasing 38% grain yield. Our results indicate that Pantoea dispersa MCA19 is a promising biofertilizer for future applications.

Molecular mapping of stripe rust resistance gene YrSN104 in Chinese wheat line Shaannong 104.

Stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is a serious yield-limiting factor for wheat production worldwide. The objective of this study was to identify and map a stripe rust resistance gene in wheat line Shaannong 104 using SSR markers. F(1), F(2) and F(3) populations from Shaannong 104/Mingxian 169 were inoculated with Chinese Pst race CYR32 in a greenhouse. Shaannong 104 carried a single dominant gene, YrSN104. Six potential polymorphic SSR markers identified in bulk segregant analysis were used to genotype F(2) and F(3) families. YrSN104 was closely linked with all six SSR markers on chromosome 1BS with genetic distances of 2.0 cM (Xgwm18, Xgwm273, Xbarc187), 2.6 cM (Xgwm11, Xbarc137) and 5.9 cM (Xbarc240). Pedigree analysis, pathogenicity tests using 26 Pst races, haplotyping of associated markers on isogenic lines carrying known stripe rust resistance genes, and associations with markers suggested that YrSN104 was a new resistance gene or an allele at the Yr24/Yr26 locus on chromosome 1BS. Deployment of YrSN104 singly or in combination to elite genotypes could play an effective role to lessen yield losses caused by stripe rust.

Partial resistance to powdery mildew in German spring wheat 'Naxos' is based on multiple genes with stable effects in diverse environments.

Powdery mildew is one of the most important wheat diseases in temperate regions of the world. Resistance breeding is considered to be an economical and environmentally benign way to control this disease. The German spring wheat cv. 'Naxos' exhibits high levels of partial and race non-specific resistance to powdery mildew in the field and is a valuable source in resistance breeding. The main objective of the present study was to map the genetic factors behind the resistance in Naxos, based on a population of recombinant inbred lines (RIL) from a cross with the susceptible CIMMYT breeding line SHA3/CBRD. Powdery mildew severity was evaluated in six field trials in Norway and four field trials in China. The major quantitative trait locus (QTL) with resistance from Naxos was detected close to the Pm3 locus on 1AS in all environments, and explained up to 35% of the phenotypic variation. Naxos was shown to carry another major QTL on 2DL and minor ones on 2BL and 7DS. QTL with resistance from SHA3/CBRD were detected on 1RS, 2DLc, 6BL and 7AL. The QTL on the 1B/1R translocation showed highly variable effects across environments corresponding to known virulence differences against Pm8. SHA3/CBRD was shown to possess the Pm3 haplotype on 1AS, but none of the known Pm3a-g alleles. The RIL population did not provide any evidence to suggest that the Pm3 allele of SHA3/CBRD acted as a suppressor of Pm8.