Investigating the possibility of induced resistance in wheat to wheat green aphid

Abstract:

Green wheat aphid, Sitobion avenae (Fabricius), has been one of the important pests of small grain cereals, especially wheat, in recent years, and its population is expanding, and it is one of the important factors of barley yellow dwarf virus transmission. Recently, it has been suggested that induced resistance can be used to reduce the insect population. Induced resistance is caused by the reaction of the plant to the feeding of the pest on the plant against the pest insects. In this research, in order to induce resistance in two wheat cultivars to the green wheat aphid, wheat cultivars named Saisons and Shiroudi were infected in the 3rd stage of leafing for periods of 0, 2, 4, 6, 8 days with five numbers of wheat green aphids inside the growth chamber set at a temperature of 25±2 °C, relative humidity of 60±5% and a photoperiod (L:D) of 14:10, and after each of these periods, the plants were They were kept free of aphids for 48 hours. Then, an adult aphid was settled on each plant (20 replicates for each treatment) and its biological parameters were studied. The results showed that in terms of the intrinsic rate of aphid population increase (rm) between the two wheat cultivars and between the time treatments on the two cultivars, there is a significant difference at the 5% probability level, so that the rm was recorded as 0.198 females/female/day on the Shiroodi cultivar and 0.075 females/female/day on the Saisons cultivar. The highest and lowest rm values ??between the time treatments in Saisons variety were obtained in the control treatment (0.092 female/female/day) and the 6 days pre-infection treatment (0.063 female/female/day), as well as in the Shiroodi variety in the control treatment (0.216 female/female/day) and the 6-day pre-contamination treatment (0.157 female/female/day) and there was a significant difference between 6 days of previous contamination and 8 days of previous contamination. did not see In terms of the average length of the growth period and the development of the pore stage, a significant difference was observed between two wheat cultivars and 5 time treatments at the probability level of 5%. The average length of emergence period and appearance of nymphs was 10.15±0.3 and 7.98±0.1 days in Saisons and Shiroudi cultivars, respectively. The highest average length of development period and appearance of nymphs was observed in Saisons and Shiroudi cultivars, 10.3 and 8.8 days, respectively, corresponding to the treatment of 6 days of previous infection, and the lowest was observed in the control treatment. The highest and lowest average number of progeny produced in Shiroudi variety and Saisons variety were 19.1 and 6.4 respectively. Also, the highest and lowest average number of progeny in a reproductive period among the treatments were seen in Saisons cultivar respectively in the control treatment (1.6) and in the 6 days previous contamination treatment (1.2) and in Shiroudi cultivar respectively in the control treatment (2.04) and in the 6 days previous contamination treatment (1.6). Therefore, it can be concluded that with 6 days of previous contamination of wheat with wheat green aphid, it is possible to create an induced resistance to this aphid, which can be useful in an IPM program of this pest. rtl;">Cereal plants (Graminae) are directly and indirectly the most important in human nutrition and among cereals, wheat, Triticum aestivum L., plays the most important role in the world. Wheat is a monocot, herbaceous and annual plant that has many species (Khodabandeh, 2007). Wheat is probably one of the first plants planted by humans, and for this reason it is considered the most important agricultural plant, because it is easier to plant than other plants and its compatibility is more in different regions with different climatic conditions. About 60% of the world's fields are under grain cultivation, the largest amount of which is under wheat cultivation. According to the report of the General Department of Statistics and Information of the Ministry of Agriculture in 2011-2018, the area under wheat cultivation in the country is 22.3 million hectares of irrigated land and 13.88 million hectares of dry land, and about 12 to 13 million tons of wheat are produced in the country annually. Wheat is the most important agricultural crop in most countries of the world, especially the Middle East, Asia, Russia, Europe, America, Canada, and Iran, and its shortage has caused many problems in the society during different eras (Serafrazi, 2011; Rashid Mozal, 2016). Among the countries of the world, China, America and India have the first to third places in terms of wheat cultivation area (Poursaleh, 2014). The country of Iran has a large production potential due to having suitable areas for planting wheat in almost most of the provinces.. Wheat, like other crops, is attacked by various pests during its growth period, among which aphids, in addition to feeding directly, cause additional damage to the plants by transmitting plant pathogens (viruses). Aphids insert their proboscis into the vessels of the host plant and feed on its fertile sap (Nouri and Rizvani, 2013; Akhtar et al. [1], 2004). In Iran, 10 species of aphids have been identified as the main and damaging pests of cereals, and wheat green aphid is one of these aphids. The green aphid of wheat with the scientific name (Fabricius) Sitobion avenae from the order of Hemiptera and the family of Aphididae is the agent of transmission of yellow dwarf viral disease of barley [2] and is considered one of the important pests of cereals in different parts of the world. This aphid had the highest density in Tehran and Golestan provinces during 1372-73, so that in Tehran province, about 94.5-31.7 percent (Nouri and Rezvani, 1373) and in Golestan province, 97 percent of the aphid population was related to this aphid (Darwish Majni and Rezvani, 1374). In addition to leaves and stems, wheat green aphid also attacks the green spikes of cereals (Farahbakhsh, 2010). The host plants of aphids (including wheat) can affect the fertility, growth and survival of aphids and cause changes in their mortality and reproduction rates in terms of host suitability, including nutritional value, secondary chemicals and morphology (Scutzko and Bosk-Perez[3], 2000). The population of aphids increases in suitable host plants and their growth and reproductive preference changes in response to changes in host quality (Honk, 1987; Honk and Martin Kova [4], 1999; Sekora and Dixon [5], 1996). The defensive chemical compounds of plants against herbivores reduce the reproduction of aphids or increase the length of their growth period and their appearance before maturity (Michaud [6], 1999; Legrand and Barbosa [7], 2000). Recent studies have shown that previous contamination of plants by insects induces chemical resistance in plants to insects. That is, when the plant is attacked and fed by a pest insect, chemical defense compounds are produced in the plant in response to the insect's damage or their concentration is increased, and thus a kind of induced resistance is created in the plant. Therefore, the purpose of this research was to investigate the possibility of using induced resistance in wheat to the green wheat aphid for use in the integrated management of this pest.

Wheat green aphid [8]

The position of the Sitobion avenae aphid in the classification of insects is as follows (Blackman and Stop[9], 2006)

                           Kingdom: Animalia

                                  Phylum:

                             Class: Insecta

                                        Order: Hemiptera

                                                      Suborder: Sternorrhyncha

Superfamily: Aphidoidea

Family: Aphididae Subfamily: Aphidinae Genus: Sitobion rtl;">                                                    Scientific name: S. avenae F.

1-1-2- Morphology

The body size of wheat green aphid is 2.1 to 1.3 mm. The body color of the female founder aphid is light green and sometimes dark green, and there is a dark green stripe on the dorsal surface of the abdomen (Figure 1-1). The head and the first thoracic strap of wingless people are straw yellow. The head and back of the thorax of winged individuals are yellowish brown, but their abdomen is green. Tentacles and cornicles are black. The length of the tentacles is 2.3 mm and their third cord is longer than the fourth cord. Cornicles are cylindrical, 0.45 mm long and longer than the tail (0.4 mm). Female winged aphids are similar in size and color to winged aphids