No abstract

Fungal pathogens deploy a barrage of secreted effectors to subvert host immunity, often by evading, disrupting, or altering key components of transcription, defense signaling, and metabolic pathways. However, the underlying mechanisms of effectors and their host targets are largely unexplored in necrotrophic fungal pathogens. Here, we describe the effector protein Ascochyta rabiei PEXEL-like Effector Candidate 25 (ArPEC25), which is secreted by the necrotroph A. rabiei, the causal agent of Ascochyta blight disease in chickpea (Cicer arietinum), and is indispensable for virulence. After entering host cells, ArPEC25 localizes to the nucleus and targets the host LIM transcription factor CaβLIM1a. CaβLIM1a is a transcriptional regulator of CaPAL1, which encodes phenylalanine ammonia lyase, the regulatory, gatekeeping enzyme of the phenylpropanoid pathway. ArPEC25 inhibits the transactivation of CaβLIM1a by interfering with its DNA binding ability, resulting in negative regulation of the phenylpropanoid pathway and decreased levels of intermediates of lignin biosynthesis, thereby suppressing lignin production. Our findings illustrate the role of fungal effectors in enhancing virulence by targeting a key defense pathway that leads to the biosynthesis of various secondary metabolites and antifungal compounds. This study provides a template for the study of less explored necrotrophic effectors and their host target functions.

The study reports snow chemistry and long range transport of pollutants at Gulmarg in north-western Himalayan region of India during winters of 2012-2013. The pH of snowmelt varied between 5.16 and 7.68 with an average of 5.90. The frequency distribution of pH of snowmelt showed that the maximum number of samples (31%) had pH between 6.81 and 7.20. However, 12% samples were observed to be acidic (below 5.6 respectively. Both local emissions as well as long range transport (LRT) of pollutants were found to be the sources of these ionic species. Backward airmass trajectory calculations showed that this site received airmasses from six major sectors i.e., i) North Atlantic Ocean origin (NAO), ii) African origin (Af), iii) Middle East origin (ME), iv) European origin (Eu), v) Western India origin (InW), vi) Pakistan origin (Pk). The highest average pH (7.58) of the snowfall was noticed during InW airmasses which had the lowest ratios of nssSO 4 2-/nssCa 2+ and NO 3 -/nssCa 2+ . Very high pH has been observed in precipitation samples at Indian sites due to buffering of acidic components by atmospheric dust rich in CaCO 3 . The lowest pH (4.94) was noticed for ME airmasses which had the highest nssSO 4 2-/nssCa 2+ and NO 3 -/nssCa 2+ ratios. Data of present study was compared with a study reported almost three decades ago. We noticed a drastic increase in the concentrations of anthropogenic components such as nssSO 4 2-(114%), NO 3 -(109%) and NH 4 + (90%). This is probably due to increase in LRT of pollutants as well as local activities during past three decades.

This study reports dustfall deposition on foliar surfaces of two medicinally important plant species i.e., Arjun (Terminalia arjuna) and Morus (Morus alba) in relation with its impact on biochemical constituents and surfaces morphology of the foliar. The study was carried out at a residential (JNU) and an industrial site (SB) of National Capital Region (NCR) Delhi. The results showed that at the industrial site, the dustfall fluxes were almost 2.5 times higher than that at the residential site. Dustfall fluxes were noticed higher on Morus foliar than Arjun foliar as the roughness of Morus foliar is greater. ) ions were also calculated by analyzing aqueous extract of dustfall at both the site. The results showed that with the increase in dustfall fluxes on the foliar surfaces, the levels of photosynthetic pigments and soluble sugar decreased while the levels of ascorbic and proline amino acid were increased at both the sites for both the plants. Dustfall fluxes had distinct seasonality having the order of fluxes as winter > summer > monsoon. Surface morphological study revealed that dust deposition adversely affects the foliar surface, cuticle and epidermal layers. Dust particle deposition ruptures and blocks the stomatal pores. As compared to the residential site, the foliar samples collected from the industrial site showed a more significant impact of dust on biochemical constituents and surface morphology.