Genetic analysis of mechanisms associated with inheritance of resistance to sheath rot of rice

Abstract

Understanding genetic mechanisms controlling inheritance of disease resistance traits is essential in breeding investigations targeting development of resistant genotypes. Using North Carolina design II, 32 F 1 hybrids were generated by crossing eight susceptible to four resistant parents and submitted for field evaluation. The analysis of general and specific combining ability (GCA and SCA) indicated involvement of additive and non-additive gene action controlling inheritance of horizontal resistance to sheath rot of rice. High GCA/SCA ratio and high heritability estimates revealed additive effects and were more predominant than none additive ones. The level of dominance indicated dominant genes was more important than recessive genes. Estimates of GCA and SCA analysis suggested that crop improvement programmes should be directed towards selection of superior parents or good combiners, emphasizing on GCA. As far as source of resistance is concerned, most promising genotypes were Cyicaro, Yunertian and Yunkeng. The predominance of additive genetic effects together with the relevance of dominant genes suggested possibilities of improving the resistance by introgression of resistance genes through recurrent selection coupled with phenotypic selection.

Short Communication: Sarocladium oryzae associated with sheath rot disease of rice in Indonesia

“…Pathogens that have a high level of virulence in susceptible hosts will produce high DSI values and a faster time for symptoms to appear. The symptoms obtained are in accordance to Nair (1976); Ou (1985) and Mvuyekure et al (2017), where the rot starts with irregular small spots and brown margins and occurs on the leaf sheaths enclosing the young panicles. The spot then enlarges and changes color to reddish-brown and the stems will rot.…”

“…Sheath rot disease symptom usually occurs on the leaf sheath which encloses panicles on rice plants. The infected leaf sheath will rot, turn grayish-brown or reddishbrown spot depending on rice cultivars and sometimes produce no grain of rice (Nair 1976;Ou 1985;Mvuyekure et al 2017). The brown spot has a length of 0.5-1 cm and width of 0.2 to 0.5 cm, while the healthy sheath remains green (Amin et al 1974).…”

“…The disease spots are linear, have irregular margins and at the next stage, the disease spot will unite and cover the entire sheath (Srinivasachary et al 2002). Pathogens that infect leaf sheath make the young panicles cannot get out of the leaf sheath and solidify or partly appear but produce empty, partly filled and turn into brown (Mvuyekure et al 2017). The losses incurred were in the form of quantitative losses (loss of yields including discoloration of grain becomes unsuitable for sale) and qualitative losses (Gopalakrishnan et al 2010;Zhang et al 2019).…”

Auxin, Abscisic Acid and Jasmonate Are the Central Players in Rice Sheath Rot Caused by Sarocladium oryzae and Pseudomonas fuscovaginae

“…High-yielding commercial rice varieties are very susceptible to rice sheath rot. Furthermore, breeding for resistant varieties is difficult because there are various sheath rot pathogens and there is a lack of knowledge about their infection strategies (Bigirimana 2016 ; Sakthivel 2001 ; Ayyadurai et al 2005 ; Chauhan et al 2017a ; Mvuyekure et al 2017 ). The main pathogens associated with this disease are the fungus Sarocladium oryzae and the bacterium Pseudomonas fuscovaginae .…”

Auxin, abscisic acid and jasmonate are the central players in rice sheath rot caused by Sarocladium oryzae and Pseudomonas fuscovaginae

“…High-yielding commercial rice varieties are very susceptible to rice sheath rot. Furthermore, breeding for resistant varieties is di cult because there are various sheath rot pathogens and there is a lack of knowledge about their infection strategies (Bigirimana 2016;Sakthivel 2001;Ayyadurai et al 2005;Chauhan et al 2017a;Mvuyekure et al 2017). The main pathogens associated with this disease are the fungus Sarocladium oryzae and the bacterium Pseudomonas fuscovaginae.…”