Rabbit Anti-Human RPS6 (Phospho-Ser240) polyclonal antibody

The plant immune system must be tightly controlled both positively and negatively to maintain normal plant growth and health. We previously identified SUPPRESSOR OF rps4-RLD1 (SRFR1) as a negative regulator specifically of effector-triggered immunity. SRFR1 is localized in both a cytoplasmic microsomal compartment and in the nucleus. Its TPR domain has sequence similarity to TPR domains of transcriptional repressors in other organisms, suggesting that SRFR1 may negatively regulate effector-triggered immunity via transcriptional control. We show here that excluding SRFR1 from the nucleus prevented complementation of the srfr1 phenotype. To identify transcription factors that interact with SRFR1, we screened an Arabidopsis transcription factor prey library by yeast two-hybrid assay and isolated six classI members of the TEOSINTE BRANCHED1/CYCLOIDEA/PCF (TCP) transcription factor family. Specific interactions were verified in planta. Although single or double T-DNA mutant tcp8, tcp14 or tcp15 lines were not more susceptible to bacteria expressing AvrRps4, the triple tcp8 tcp14 tcp15 mutant displayed decreased effector-triggered immunity mediated by the resistance genes RPS2, RPS4, RPS6 and RPM1. In addition, expression of PATHOGENESIS-RELATED PROTEIN2 was attenuated in srfr1-4 tcp8-1 tcp14-5 tcp15-3 plants compared to srfr1-4 plants. To date, TCP transcription factors have been implicated mostly in developmental processes. Our data indicate that one function of a subset of TCP proteins is to regulate defense gene expression in antagonism to SRFR1, and suggest a mechanism for an intimate connection between plant development and immunity.

Phytophthora root and stem rot of soybean is caused by the oomycete pathogen Phytophthora sojae, which can infect plants at all stages of growth when soil conditions favour pathogen development. In Manitoba, the acreage of commercial soybean has increased dramatically in recent years. Root and stem rot caused by P. sojae was first detected in commercial soybean in Manitoba in 2011. The objectives of this study were to characterize the pathotype diversity of P. sojae infecting common soybean varieties in Manitoba and identify Rps genes effective against this population. Forty-four, 77 and 89 soybean fields located in the major production areas in Manitoba were surveyed in 2014, 2016 and 2017, respectively. Pathogen collections of 32 (2014), 34 (2016) and 35 (2017) isolates were made each year and evaluated for pathotype classification. Pathotypes of P. sojae were identified based on the pattern of their reactions on a differential set, which included the Rps genes / a, lb, lc, Id, 1k, 3a, 6 and 7. The most common pathotype was la, lc, 7 (race 4), which comprised 45% of the 101 isolates examined, followed by the pathotypes la, lb, lc, lk, 7 (race 25) and la, lb, lk, 7 (race 28), comprising 34% and 11% of the isolates, respectively. The resistance genes Rpslc and lk are the most common genes deployed in Manitoba. Based on the results of this study, stacking of resistance genes Rpsld, Rps3a and Rps6 in soybean cultivars targeted for deployment in Manitoba would prove useful in reducing the severity of Phytophthora root and stem mt.