Abstract
BackgroundThe rice gall midge (RGM, Orseolia oryzae, Wood-Mason), an important stem-feeding pest worldwide, has caused serious production losses over the past decades. Rice production practices indicate that the most reliable method for managing RGM is the deployment of cultivars that incorporate host resistance. However, the conventional phenotypic screening method of rice resistance to RGM suggested by the International Rice Research Institute (IRRI) has been used for approximately 30 years, and only 12 rice varieties/lines (including controls) can be evaluated in one tray. It is not suitable for high-throughput phenotyping of rice germplasm. Moreover, a suitable method to prepare samples for molecular biological studies of rice resistance against RGM is imperative with the rapid development of modern molecular techniques.ResultsThe proper density of seedlings/RGM was determined for four seeding arrangements. A high-throughput phenotyping method (HTPM) for 60 lines/varieties infested with 36 female RGM adults in one tray, as described by method 4–3 (seeded 60 lines/varieties), was developed and verified using mutant screening. Furthermore, one RGM resistance gene flanked by markers 12RM28346 and 12RM28739 on chromosome 12 was simultaneously detected using method 2–2 (seeded 30 lines/varieties in one tray) treated with 24 RGM and analyzed using conventional and simplified grading systems. Genetic analysis of the RGM resistance gene was confirmed using a method identical to that suggested by IRRI. Finally, one bucket with 24 seedlings treated with at least five female RGM adults was efficacious and could offer adequate samples for insect development observation or molecular biological studies.ConclusionA highly efficient and reliable procedure for evaluation of resistance in rice to RGM was developed and improved, and was verified through mutant screening, gene mapping, genetic analysis, and insect growth and development observations.
Highlights
Rice (Oryza sativa L.), one of the most important food crops, supplies more than 20% of the global dietary energy and feeds more than half of the world’s population [1]
Determination of density of seedlings/Rice gall midge (RGM) for the free‐feeding resistance evaluation A significant negative correlation was observed between percentage of silver shoots (PSS) and density of seedlings/RGM (r = 0.904, p < 0.01)
Determination of density of seedlings/RGM for the no‐choice feeding resistance evaluation The PSS was less than 60% when the buckets were treated with 1–4 insects
Summary
Rice (Oryza sativa L.), one of the most important food crops, supplies more than 20% of the global dietary energy and feeds more than half of the world’s population [1]. Seedlings with inflated shoots or multiple tillers are considered to be susceptible according to the Standard Evaluation System of the RGM described by the International Rice Research Institute (IRRI) [5,6,7]. The conventional phenotypic screening method of rice resistance to RGM suggested by the International Rice Research Institute (IRRI) has been used for approximately 30 years, and only 12 rice varieties/lines (including controls) can be evaluated in one tray. It is not suitable for high-throughput phenotyping of rice germplasm. A suitable method to prepare samples for molecular biological studies of rice resistance against RGM is imperative with the rapid development of modern molecular techniques
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