Enhanced soybean (Glycine max L.) plant growth and nodulation by Bradyrhizobium japonicum-SB1 in presence of Bacillus thuringiensis-KR1

Abstract

Nodulation and subsequent nitrogen fixation are important factors that determine the productivity of soybean (Glycine max L.). The beneficial effects of nodulation can be enhanced when rhizobial inoculation is combined with plant-growth-promoting bacteria (PGPB). The PGPB strain Bacillus thuringiensis-KR1, originally isolated from the nodules of Kudzu vine (Pueraria thunbergiana), was found to promote growth of soybean plants (variety VL Soya 2) under Jensen's tube and growth pouch conditions, when co-inoculated with Bradyrhizobium japonicum-SB1. Co-inoculation with Bacillus thuringiensis-KR1 (at a cell density of 10 cfu) provided the highest and most consistent increase in nodule number, shoot weight, root weight, root volume, and total biomass, over rhizobial inoculation and control, under both conditions. The results demonstrate the potential benefits of using nonrhizobial nodule occupants of wild legumes for the co-inoculation of soybean, with Bradyrhizobium japonicum-SB1, in order to achieve plant-growth promotion and increased nodulation.     

Identification and fine-mapping of Xa33, a novel gene for resistance to Xanthomonas oryzae pv. oryzae

Broadening of the genetic base for identification and transfer of genes for resistance to insect pests and diseases from wild relatives of rice is an important strategy in resistance breeding programs across the world. An accession of Oryza nivara, International Rice Germplasm Collection (IRGC) accession number 105710, was identified to exhibit high level and broad-spectrum resistance to Xanthomonas oryzae pv. oryzae. In order to study the genetics of resistance and to tag and map the resistance gene or genes present in IRGC 105710, it was crossed with the bacterial blight (BB)-susceptible varieties 'TN1' and 'Samba Mahsuri' (SM) and then backcrossed to generate backcross mapping populations. Analysis of these populations and their progeny testing revealed that a single dominant gene controls resistance in IRGC 105710. The BC(1)F(2) population derived from the cross IRGC 105710/TN1//TN1 was screened with a set of 72 polymorphic simple-sequence repeat (SSR) markers distributed across the rice genome and the resistance gene was coarse mapped on chromosome 7 between the SSR markers RM5711 and RM6728 at a genetic distance of 17.0 and 19.3 centimorgans (cM), respectively. After analysis involving 49 SSR markers located between the genomic interval spanned by RM5711 and RM6728, and BC(2)F(2) population consisting of 2,011 individuals derived from the cross IRGC 105710/TN1//TN1, the gene was fine mapped between two SSR markers (RMWR7.1 and RMWR7.6) located at a genetic distance of 0.9 and 1.2 cM, respectively, from the gene and flanking it. The linkage distances were validated in a BC(1)F(2) mapping population derived from the cross IRGC 105710/SM//2 × SM. The BB resistance gene present in the O. nivara accession was identified to be novel based on its unique map location on chromosome 7 and wider spectrum of BB resistance; this gene has been named Xa33. The genomic region between the two closely flanking SSR markers was in silico analyzed for putatively expressed candidate genes. In total, eight genes were identified in the region and a putative gene encoding serinethreonine kinase appears to be a candidate for the Xa33 gene.     

Seaweed-based biostimulant improves photosynthesis and effectively enhances growth and biofuel potential of a green microalga Chlorella variabilis

Aquaculture International - The main aim of the present study was to determine the effects of a seaweed-based biostimulant’s supplementation on the growth of Chlorella variabilis. A liquid...     

Landraces of cowpea, <Emphasis Type="Italic">Vigna</Emphasis><Emphasis Type="Italic">unguiculata</Emphasis> (L.) Walp., as potential sources of genes for unique characters in breeding

Cowpea landraces belonging to Vigna unguiculata (L.) Walp. subsp. unguiculata cv.-gr. unguiculata and cv.-gr. sesquipedalis collected from part of the Deccan Plateau and West Coast of India were evaluated to (i) identify the diverse source(s) of variation for improved characters like pods/peduncle and seed index (ii) study the response of landraces for adaptation to drought and heat stress and (iii) understand the breeding value of a landrace in the genetic improvement of a popular cowpea cultivar. Landraces were evaluated for various morphological characters, pods/peduncle, seed index and other economically important agronomic traits, rust resistance and drought and heat tolerance in different years and environments. Landraces were found as an important source of genetic variability for pods/plant, pods/peduncle, better pod filling ability (seed index), grain yield/plant as well as drought and heat tolerance and rust resistance. Hybridization between C 152 (cv.) and DWDCC 016 (landrace) resulted in release of new variation not present in the two parents. Thus the landrace, DWDCC 016, can be utilized to improve cultivated varieties by transferring to them the economically valuable traits like pods/peduncle and seed index thereby enhancing realisation of sink potential and ultimately grain yield in a sustainable way.     

Long-term influence of different production systems on potassium buffering capacity of Typic Ustochrept soil

Imbalanced application of nutrients in the intensively cropped areas results in deterioration of soil fertility. Application of recommended dose of potassium (K) is essential for improving the use efficiency of other nutrients. To assess the buffering capacity of soil, three composite soil samples were collected from the surface soil (0–30?cm) during 2015 from 3 production systems viz., organic, inorganic and integrated which was maintained from 2004 with basmati rice–wheat–Sesbania system under Network Project on Organic Farming at ICAR-Indian Institute of Farming Systems Research, Modipuram. Fractionation of potassium (K) was achieved by sequential extraction of soil samples with distilled water, ammonium acetate and nitric acid in the same order. The relationship between the adsorbed and equilibrium potassium concentration, quantity was determined by plotting Freundlich adsorption isotherms. This was used to determine the buffering capacity and the concentration levels of potassium adsorbed on un-specific sites in the soil. The suitability of the adsorption equation was determined by applying the least square regression analysis. The results revealed that available potassium in the soils ranged from 119.51 to 135.01?mg/kg with 126.02?±?5.24?mg/kg as mean (ammonium acetate method) while water soluble and nitric acid extracted potassium ranged from 28.51 to 29.05?mg/kg and 2594.49?±?19.33?mg/kg (mean) in various production systems. The mean free energy of replacement was found to be ?1998.01?±?28.38?cal/mol indicating that soils have comparatively higher potassium supply under organic system. The potassium buffering capacity of the soils was found to be 0.7462?±?0.16?mg/kg, 0.6295?±?0.20?mg/kg and 0.6774?±?0.09?mg/kg in organic, integrated and inorganic systems, respectively. The amount of potassium adsorbed on un-specific sites of the organic, integrated and inorganic systems was found to be 7.4730?±?1.81, 15.11?±?2.40 and 11.6 89?±?3.58?mg/kg, respectively. It can be concluded that long-term organic production system improves K⁺ buffering capacity of Typic Ustochrept soil as compare to the integrated as well as inorganic production systems.