jasmonic acid (JA) and ethylene (ET) signaling, activation of NPR1 gene,
transcription factors (MYB72 and MYC2) and callose formation cause induction
of induced systemic resistance (ISR). Both SAR and ISR cause the plants to
acquire a special condition of priming, thus making them more tolerant or
resistant to existent and subsequent infections by broad spectrum of pathogens
and insects. The rhizo-microflora is extremely diverse and implicated in elicitation of ISR. Moreover, the biocontrol of soil borne diseases by PGPM can be a
significant contributor to crop yield under various biotic stress conditions. These
beneficial microbes by various initiative mechanisms, including production and
release of different substances, trigger physiological and biochemical changes for
biotic stress tolerance in plants. Because conventional applications against
pathogens are inefficient and disease management is highly challenging, the use
of beneficial microorganisms has been suggested as a biocontrol solution, for
providing an eco-friendly and cost-effective alternative for sustainable crop
production involving the disease resistance by ISR and promotion of growth in
plants.
Keywords
Biotic stresses · PAMP-triggered immunity (PTI) · Effector-triggered immunity
(ETI) · Plant growth promoting microorganisms (PGPM) · Systemic acquired
resistance (SAR) · Induced systemic resistance (ISR)
10.1 Introduction
Plants face various kinds of biotic stresses in the form of damage, disease, and
competition due to their exposure to pathogens, insects, and weeds competing for
resources, which is a major reason for quantitative and qualitative losses in terms of
crop yield in agriculture. It has been reported that about 15% of total global food
production is lost due to different diseases caused by pathogens (Onaga and Wydra
2016). Climate change may reduce food production further as it may cause evolution
of aggressive phytopathogens and expansion of disease or insect pest outbreaks to
newer areas (Anderson et al. 2004; Ijaz and Khan 2012). Biotic stress divests the
plants of their nutrients and causes reduced robustness and mortality in severe
circumstances. Several factors such as unfavorable weather conditions, poor cropmanagement and cultivation practices, and vulnerable or less resistant crop varieties
can aggravate biotic stress (Das and Rakshit 2016). Therefore, management of stress
promoting factors is paramount for sustainable crop productivity.
Exploration of resistance mechanisms used by plants to combat stress-associated
biotic factors is one of the approaches that helps in development of resistant cultivars
using the diverse disease and pest resistance alleles prevailing in gene pools of
cultivated crops and their wild relatives (Islam et al. 2016). Further, many microbes,
especially those belong to rhizomicrobiome, can suppress several diseases and
ameliorate the harmful impact of the biotic and abiotic stresses by stimulation of
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L. Thomas and I. Singh
transcription factors (MYB72 and MYC2) and callose formation cause induction
of induced systemic resistance (ISR). Both SAR and ISR cause the plants to
acquire a special condition of priming, thus making them more tolerant or
resistant to existent and subsequent infections by broad spectrum of pathogens
and insects. The rhizo-microflora is extremely diverse and implicated in elicitation of ISR. Moreover, the biocontrol of soil borne diseases by PGPM can be a
significant contributor to crop yield under various biotic stress conditions. These
beneficial microbes by various initiative mechanisms, including production and
release of different substances, trigger physiological and biochemical changes for
biotic stress tolerance in plants. Because conventional applications against
pathogens are inefficient and disease management is highly challenging, the use
of beneficial microorganisms has been suggested as a biocontrol solution, for
providing an eco-friendly and cost-effective alternative for sustainable crop
production involving the disease resistance by ISR and promotion of growth in
plants.
Keywords
Biotic stresses · PAMP-triggered immunity (PTI) · Effector-triggered immunity
(ETI) · Plant growth promoting microorganisms (PGPM) · Systemic acquired
resistance (SAR) · Induced systemic resistance (ISR)
10.1 Introduction
Plants face various kinds of biotic stresses in the form of damage, disease, and
competition due to their exposure to pathogens, insects, and weeds competing for
resources, which is a major reason for quantitative and qualitative losses in terms of
crop yield in agriculture. It has been reported that about 15% of total global food
production is lost due to different diseases caused by pathogens (Onaga and Wydra
2016). Climate change may reduce food production further as it may cause evolution
of aggressive phytopathogens and expansion of disease or insect pest outbreaks to
newer areas (Anderson et al. 2004; Ijaz and Khan 2012). Biotic stress divests the
plants of their nutrients and causes reduced robustness and mortality in severe
circumstances. Several factors such as unfavorable weather conditions, poor cropmanagement and cultivation practices, and vulnerable or less resistant crop varieties
can aggravate biotic stress (Das and Rakshit 2016). Therefore, management of stress
promoting factors is paramount for sustainable crop productivity.
Exploration of resistance mechanisms used by plants to combat stress-associated
biotic factors is one of the approaches that helps in development of resistant cultivars
using the diverse disease and pest resistance alleles prevailing in gene pools of
cultivated crops and their wild relatives (Islam et al. 2016). Further, many microbes,
especially those belong to rhizomicrobiome, can suppress several diseases and
ameliorate the harmful impact of the biotic and abiotic stresses by stimulation of
298
L. Thomas and I. Singh