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Efficient irrigation management is vital for conserving water and maximizing productivity, making the crop water stress index (CWSI) a powerful remote sensing tool. CWSI computation requires lower and upper baselines, corresponding to no-stress and severe stress conditions, respectively. This study aims to compare two different methods for determining those baselines. In the empirical method, the non-water-stressed baseline (NWSB) is derived by the linear regression of the canopy-air temperature difference against vapor pressure deficit (VPD) for a well-watered crop. The combined method compares the NWSB coefficients to theoretical expressions to estimate aerodynamic and canopy resistance at potential transpiration. This work used infrared radiometers (IRR) to measure the canopy temperature of bean plants (Phaseolus vulgaris L.) cultivar 'IAC1850' under center-pivot irrigation. Since the empirical method is susceptible to fluctuations in meteorological data, an expressive amount of data had to be filtered out. When comparing the two methods, the RMSE is 1.0 °C for the lower baseline and 1.8 °C for the upper baseline. Future studies could use these baselines to provide CWSI maps from thermographic images. [ABSTRACT FROM AUTHOR]

Genetic resistance of common bean (Phaseolus vulgaris L.) against angular leaf spot (ALS), caused by the fungus Pseudocercospora griseola, is conferred by quantitative trait loci (QTL). In this study, we determined the gene content of the major QTL ALS10.1 located at the end of chromosome Pv10, and identified those that are responsive to ALS infection in resistant (CAL 143) and susceptible (IAC-UNA) genotypes. Based on the current version of the common bean reference genome, the ALS10.1 core region contains 323 genes. Gene Ontology (GO) analysis of these coding sequences revealed the presence of genes involved in signal perception and transduction, programmed cell death (PCD), and defense responses. Two putative R gene clusters were found at ALS10.1 containing evolutionary related coding sequences. Among them, the Phvul.010G025700 was consistently up-regulated in the infected IAC-UNA suggesting its contribution to plant susceptibility to the fungus. We identified six other genes that were regulated during common bean response to P. griseola; three of them might be negative regulators of immunity as they showed opposite expression patterns during resistant and susceptible reactions at the initial phase of fungal infection. Taken together, these findings suggest that common bean reaction to P. griseola involves transcriptional modulation of defense genes in the ALS10.1 locus, contributing to resistance or susceptibility depending on the plant-pathogen interaction.

Phaseolus vulgaris is an important grain legume for human consumption. Recently, association mapping studies have been performed for the species aiming to identify loci underlying quantitative variation of traits. It is now imperative to know whether the linkage disequilibrium (LD) reflects the true association between a marker and causative loci. The aim of this study was to estimate and analyze LD on a diversity panel of common beans using ordinary r 2 and r 2 extensions which correct bias due to population structure ( r S 2 ), kinship ( r V 2 ), and both ( r V S 2 ). A total of 10,362 single nucleotide polymorphisms (SNPs) were identified by genotyping by sequencing (GBS), and polymorphisms were found to be widely distributed along the 11 chromosomes. In terms of r 2 , high values of LD (over 0.8) were identified between SNPs located at opposite chromosomal ends. Estimates for r V 2 were lower than those for r S 2 . Results for r V 2 and r V S 2 were similar, suggesting that kinship may also include information on population structure. Over genetic distance, LD decayed to 0.1 at a distance of 1 Mb for r V S 2 . Inter-chromosomal LD was also evidenced. This study showed that LD estimates decay dramatically according to the population structure, and especially the degree of kinship. Importantly, the LD estimates reported herein may influence our ability to perform association mapping studies on P. vulgaris. [ABSTRACT FROM AUTHOR]