Sep 2014

Influence of elevated atmospheric CO2 on Fusarium wilt (Fusarium oxysporum f. sp. ciceris) of chickpeaM Sharma, R Ghosh, R Telangre and A SenguptaInternational Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru, PO 502324, Telangana, India

Figure 1. Open Top Chamber (OTC) facility at ICRISAT.

Figure 2. Disease progress in susceptible cultivar (JG 62) under ambient and elevated CO2 concentrations.

Table 1. Effect of elevated CO2 on Fusarium wilt incidence in chickpea.

GenotypesIncubation period (days) FW incidence (%) AUDPC

350 ppm 550 ppm 350 ppm 550 ppm 350 ppm 550 ppm

JG 62 18 12 100 100 1423 1890

WR 315 - - 0 0 0 0

IntroductionClimate change has a number of observed, anticipated and possible consequences on crop health. Among the climate change variables, role of CO2 is becoming important as it is predicted to increase from the present level of 350 ppm to 550 ppm by 2050 and 700 ppm by end of the century. Numerous changes have been observed on growth and yield of plants due to elevated CO2, but there is limited information available on its effect on plant disease development and defence responses. Here, we are reporting the effect of elevated CO2 on Fusarium wilt [Fusarium oxysporum f. sp. ciceris (Foc)] of chickpea and biochemical changes during Foc – chickpea – CO2 interaction.

Objectives• To assess the effect of elevated CO2 on Fusarium wilt symptoms and

disease development.• To study biochemical changes as affected by elevated CO2 in Foc –

chickpea pathosystem.

Materials and methods• Two genotypes of chickpea – a wilt susceptible (JG 62) and a resistant

(WR 315) and pathogen Foc Race 1 were selected for this study.• The experiment was conducted in Open Top Chambers (OTCs) at

ICRISAT, maintained at ambient (350 ppm) and elevated (550 ppm) CO2 concentrations (Figure 1).

• Data on incubation period and periodical disease development was recorded.

• Biochemical changes (APX, GPX, SOD, CAT, DAO and GR) in susceptible (JG 62) and resistant (WR 315) cultivars of chickpea challenged with Foc were measured in plants grown at ambient (350 ppm) and elevated (550 ppm) CO2 levels at 7, 14 and 21 days after inoculation.

Results• Incubation period advanced in susceptible cultivar by 6 days at 550 ppm.• Disease progressed faster in elevated CO2 compared with ambient in

susceptible cultivar. However, wilt incidence was statistically at par after 28 days both under ambient and elevated CO2 (Figure 2).

• Area Under Disease Progress Curve (AUDPC) was higher (33%) in elevated CO2 than in ambient (Table 1).

• Under elevated CO2 : � The uninoculated plants had higher enzyme activities compared to ambient level in both the cultivars irrespective of time points (Figure 3).

� APX, GPX and SOD activities were significantly higher in susceptible cultivar as compared to resistant cultivar.

� CAT activities were significantly higher in resistant cultivar. � The DAO activity decreased in susceptible cultivar but increased in resistant cultivar.

� GR activities were found non-significant. � Plant biomass was found to be increased.

Figure 3. Changes in biochemical enzymes (APX, GPX, SOD, CAT, DAO and GR) in Foc-challenged susceptible (JG 62) and resistant (WR 315) cultivars under elevated CO2.

ConclusionThe global warming predicted could induce an increase in the incidence of diseases caused by Fusarium species. Changes in biochemical enzymes were detected as consequences of elevated CO2 concentration. However, the potential impact of elevated atmospheric CO2 on range of genotypes with different disease reaction and on soil microbial composition and activity need further studies.Acknowledgements: The funding support by Department of Science and Technology, GoI, for conducting this study is acknowledged.

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