Selection of stable housekeeping genes for gene expression studies in different varieties of black pepper (Piper nigrum L.)

Real Time quantitative PCR (RT-qPCR) is a widely used technique to study the transcript level modulation of genes during developmental stages of crop plants as well as in stress responses. Suitable reference genes have not been validated in many plants including black pepper. In this study, expression stability of six commonly used housekeeping genes viz., actin, ?-tubulin, elongation factor, initiation factor, ubiquitin and glyceraldehyde 3- phosphate dehydrogenase were evaluated by RT-qPCR during the growth of the black pepper inflorescence of varieties viz., Panniyur 1, Karimunda and Thekken. The results were analyzed using geNorm and Normfinder statistical algorithms. Stable reference gene is critical for the accurate normalization of target gene data in RT-qPCR. In this study actin, elongation factor and initiation factor were identified as the most stable housekeeping gene in different black pepper varieties viz., Thekken, Panniyur 1 and Karimunda respectively. Actin in combination with GAPDH and elongation factor were obtained as optimal reference genes for Thekken. It is the first report on identification of stable housekeeping gene in different varieties of black pepper and can aid in expression studies in black pepper for yield improvement. The study will aid in normalization of gene expression studies in different varieties of black pepper

Productivity and nitrogen use efficiency of rice under conventional and organic nutrition

The current study demonstrates the influence of conventional and organic nutrient management practices on nitrogen use efficiency, growth, yield, and physiological and biochemical parameters in four rice varieties, namely, Jaiva, Ezhome 2, Jyothi and Uma. Growth parameters, grain yield per hill, and physiological and biochemical parameters were higher under conventional management for all rice varieties. Although the nitrogen use efficiency of each variety varied significantly with nutrient management practices, the variation was least in Jaiva (23.8%), which is the organic rice variety released by Kerala Agricultural University. The rice varieties Jaiva and Ezhome 2 showed consistency in the grain weight per panicle under both conventional (Jaiva- 4.57 g, Ezhome 2- 5.86 g) and organic (Jaiva, 4.24 g, Ezhome 2, 4.54 g) management. The soil nitrogen content at the tillering stage (0.66**) showed a significantly higher positive correlation with nitrogen use efficiency under organic management. The results of the study provide a better understanding of factors that can lead to a sustained yield in organic rice production in terms of nitrogen use efficiency

In Vitro and In Planta Antagonistic Effect of Endophytic Bacteria on Blight Causing <i>Xanthomonas axonopodis</i> pv. <i>punicae</i>: A Destructive Pathogen of Pomegranate

Pomegranate bacterial blight caused by Xanthomonas axonopodis pv. punicae (Xap) is a highly destructive disease. In the absence of host resistance to the disease, we aimed to evaluate the biocontrol potential of endophytic bacteria against Xap. Thus, in this study, we isolated endophytes from pomegranate plants, identified them on the basis of 16S rDNA sequencing, tested them against Xap, and estimated the endophyte-mediated host defense response. The population of isolated endophytes ranged from 3 × 106 to 8 × 107 CFU/g tissue. Furthermore, 26 isolates were evaluated for their biocontrol activity against Xap, and all the tested isolates significantly reduced the in vitro growth of Xap (15.65% ± 1.25% to 56.35% ± 2.66%) as compared to control. These isolates could reduce fuscan, an uncharacterized factor of Xap involved in its aggressiveness. Lower blight incidence (11.6%) and severity (6.1%) were recorded in plants sprayed with endophytes 8 days ahead of Xap spray (Set-III) as compared to control plants which were not exposed to endophytes (77.33 and 50%, respectively%) during in vivo evaluation. Moreover, significantly high phenolic and chlorophyll contents were estimated in endophyte-treated plants as compared to control. The promising isolates mostly belonged to the genera Bacillus, Burkholderia, and Lysinibacillus, and they were deposited to the National Agriculturally Important Microbial Culture Collection, India