Differential host responses of sugarcane to Colletotrichum falcatum reveal activation of probable effector triggered immunity (ETI) in defence responses.

KEY MESSAGE: The differential compatibility responses of sugarcane to Colletotrichum falcatum pathotypes depend on the nature of both host primary defence signalling cascades and pathogen virulence. The complex polyploidy of sugarcane genome and genetic variations in different cultivars of sugarcane remain a challenge to identify and characterise specific genes controlling the compatible and incompatible interactions between sugarcane and the red rot pathogen, Colletotrichum falcatum. To avoid host background variation in the interaction study, suppression subtractive hybridization (SSH)-based next-generation sequencing (NGS) technology was used in a sugarcane cultivar Co 7805 which is compatible with one C. falcatum pathotype but incompatible with another one. In the incompatible interaction (ICI-less virulent) 10,038 contigs were assembled from ~ 54,699,263 raw reads, while 4022 contigs were assembled from ~ 52,509,239 in the compatible interaction (CI-virulent). The transcripts homologous to CEBiP receptor and those involved in the signalling pathways of ROS, Ca2+, BR, and ABA were expressed in both interaction responses. In contrast, MAPK, ET, PI signalling pathways and JA amino conjugation related transcripts were found only in ICI. In temporal gene expression assays, 16 transcripts showed their highest induction in ICI than CI. Further, more than 17 transcripts specific to the pathogen were found only in CI, indicating that the pathogen colonizes the host tissue whereas it failed to do so in ICI. Overall, this study has identified for the first time that a probable PAMP triggered immunity (PTI) in both responses, while a more efficient effector triggered immunity (ETI) was found only in ICI. Moreover, pathogen proliferation could be predicted in CI based on transcript expression, which were homologous to Glomerella graminicola, the nearest clade to the perfect stage of C. falcatum (G. tucumanensis).

The complete genome sequence of a south Indian isolate of Rice tungro spherical virus reveals evidence of genetic recombination between distinct isolates.

In this study, complete genome of a south Indian isolate of Rice tungro spherical virus (RTSV) from Andhra Pradesh (AP) was sequenced, and the predicted amino acid sequence was analysed. The RTSV RNA genome consists of 12,171 nt without the poly(A) tail, encoding a putative typical polyprotein of 3,470 amino acids. Furthermore, cleavage sites and sequence motifs of the polyprotein were predicted. Multiple alignment with other RTSV isolates showed a nucleotide sequence identity of 95% to east Indian isolates and 90% to Philippines isolates. A phylogenetic tree based on complete genome sequence showed that Indian isolates clustered together, while Vt6 and PhilA isolates of Philippines formed two separate clusters. Twelve recombination events were detected in RNA genome of RTSV using the Recombination Detection Program version 3. Recombination analysis suggested significant role of 5' end and central region of genome in virus evolution. Further, AP and Odisha isolates appeared as important RTSV isolates involved in diversification of this virus in India through recombination phenomenon. The new addition of complete genome of first south Indian isolate provided an opportunity to establish the molecular evolution of RTSV through recombination analysis and phylogenetic relationship.

Radiation inactivation studies on the rabbit kidney sodium-dependent glucose transporter.

Rabbit kidney cortical brush-border membrane vesicles were irradiated in the frozen state with increasing doses of high energy electrons from a Van de Graaff generator. Sodium-dependent D-glucose and L-alanine transport showed a simple exponential loss of activity with increasing radiation dosage. Target size calculation based on these data gives estimates of 1.0 X 10(6) daltons for the glucose transporter and 1.2 X 10(6) daltons for the alanine transporter. A highly purified glucose transport protein extracted from rabbit kidney cortex was similarly irradiated both before and after reconstitution into liposomes. The target size of this purified glucose transporter was 343,000 daltons, based on inactivation of transport. The intensity of the major 165,000-dalton sodium dodecyl sulfate-gel electrophoresis band of this preparation was decreased by radiation. The decrease in staining intensity was dose-dependent, yielding a target size of 298,000 daltons, in situ. We propose that the purified glucose transporter reconstituted into liposomes is a tetramer comprised of 85,000-dalton subunits.