Abstract
The Sakon Nakhon (SKN) rice cultivar is non-photosensitive, rich in aroma, and an excellent choice for cooking quality; which adapts well to both upland and lowland conditions. Furthermore, it has been adopted by Thailand’s sugarcane growers, as it has proved fit for an upland crop preceding the sugarcane cropping system. However, SKN is very susceptible to blast disease caused by Pyricularia oryzae. The purpose of this study was to breed SKN for blast resistance, using marker-assisted backcrossing, together with phenotypic selection. The breeding population was constructed by crossing the SKN (recurrent) with the RD6 introgression line (donor), which contained four blast resistant quantitative trait loci (QTLs). Franking microsatellite markers for blast resistance QTLs on chromosomes 1, 2, 11 and 12 were used for selection through BC2F2. Thirteen BC2F3 selected lines were evaluated under greenhouse conditions, and seven lines of BC2F4 were evaluated against blast, along with their agronomic traits, under field conditions (upland and lowland). SKN 39-10-19-29-12 and SKN 39-10-19-29-13 presented high resistance to leaf and neck blast; and were non-photosensitive, with the same agronomic traits as the SKN. This study successfully demonstrates the improvement of the recommended SKN variety blast resistance, while maintaining similar agronomic traits.
Highlights
Rice (Oryza sativa L.) is the most important economic crop of Thailand
Thirty-nine F1-plants were obtained through crossing Sakon Nakhon (SKN) and RD6 NIL; all of which were heterozygous after confirmation by RM 319, which proved polymorphic between the two parental lines
Our results indicated that a single blast resistant QTL on chromosome 11 contained the same broad spectrum of resistance as the IR64, the international resistance standard check
Summary
Rice (Oryza sativa L.) is the most important economic crop of Thailand. Grown in both lowland and upland conditions, Thailand has remained Southeast Asia’s largest rice exporter for several decades.More than 50% of Thailand’s rice production area (about 6.4 Mha in 2014) belongs to its Northeastern region, which is Thailand’s largest area of rain-fed rice production [1]. Rice (Oryza sativa L.) is the most important economic crop of Thailand. Grown in both lowland and upland conditions, Thailand has remained Southeast Asia’s largest rice exporter for several decades. More than 50% of Thailand’s rice production area (about 6.4 Mha in 2014) belongs to its Northeastern region, which is Thailand’s largest area of rain-fed rice production [1]. More than 0.8 Mha of Northeast Thailand has the capacity to grow upland rice. The climate is drier than other regions, yet proves suitable for growth, as upland rice needs less water to grow [4]. Farmers generally grow upland rice as the major crop for household consumption, or by rotation cropping with sugarcane or cassava to increase their income, and improve soil fertility [5]
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