Understanding the complexity of disease-climate interactions for rice bacterial panicle blight under tropical conditions

Abstract

Bacterial panicle blight (BPB) caused by Burkholderia glumae is one of the main concerns for rice production in the Americas since bacterial infection can interfere with the grain-filling process and under severe conditions can result in high sterility. B. glumae has been detected in several rice-growing areas of Colombia and other countries of Central and Andean regions in Latin America, although evidence of its involvement in decreasing yield under these conditions is lacking. Analysis of different parameters in trials established in three rice-growing areas showed that, despite BPB presence, severity did not explain the sterility observed in fields. PCR tests for B. glumae confirmed low infection in all sites and genotypes, only 21.4% of the analyzed samples were positive for B. glumae. Climate parameters showed that Montería and Saldaña registered maximum temperature above 34°C, minimum temperature above 23°C, and Relative Humidity above 80%, conditions that favor the invasion model described for this pathogen in Asia. Our study found that in Colombia, minimum temperature above 23°C during 10 days after flowering is the condition that correlates with disease incidence. Therefore, this correlation, and the fact that Montería and Saldaña had a higher level of infected samples according to PCR tests, high minimum temperature, but not maximum temperature, seems to be determinant for B. glumae colonization under studied field conditions. This knowledge is a solid base line to design strategies for disease control, and is also a key element for breeders to develop strategies aimed to decrease the effect of B. glumae and high night-temperature on rice yield under tropical conditions.

Fig 1. Experimental design used for field trials.

Plot size and sampling strategy to measure disease parameters (A1 and A2, 0.05 m²) and sterility (A3 and A4, 0.2 m²).

Fig 2. Specificity test for P11 primers.

PCR Amplification from Different Burkholderia Species and Other Rice-Associated Bacteria. M, molecular marker 1 kb plus; 1, B. phymatum; 2, B. cepacea; 3, B. tuberum; 4, B. graminis; 5, B. caledonica; 6, B. glatthei; 7, B. terricola; 8, B. xenovorans; 9, B. mimosarum; 10, B. sabiae; 11, B. diazotrophica; 12, B. symbiotica; 13, B. fungorum; 14, B. phenazinium; 15, B. phytofirmans; 16, B. vietnamiensis; 17, B. glumae; 18, B. gladioli; 19, B. kururiensis; 20, B. sacchari; 21, B. unamae; 22, B. tropica; 23, B. plantarii; 24, B. glumae 3252–8; 25, A. avenae subsp. avenae 4008–2; 26, P. fuscovaginae 4500–2; 27, Pantoea agglomerans TG7; 28, X. oryzae pv. oryzae PX0116; 29, X. oryzae pv. oryzicola BLS256; 30, blank.

Fig 3. PCR amplification with P11 primers using DNA from rice seeds with different levels of disease severity.

M, molecular marker 1 kb plus; 1 to 15, naturally infected rice seeds; 16, DNA B. glumae 3252–8; 17, DNA B. glumae 3252–8; 18, negative control (PCR reaction mix with water); 19, negative control (PCR reaction mix only).

Fig 4

Pearson Correlation between Disease Variables and Climate Variables for 10 Days Before (A) and 10 Days After (B) Flowering Date. HR, relative humidity; TMAX, maximum temperature; TMIN, minimum temperature; RAIN, precipitation; INC, disease incidence; STE, spikelet sterility.