Abstract
BackgroundIn rice (Oryza sativa) and other grains, weak growth (dwarfism, short panicle length, and low seed-setting rate) and early senescence lead to reduced yield. The molecular mechanisms behind these processes have been widely studied; however, the complex genetic regulatory networks controlling growth and senescence require further elucidation.ResultsWe isolated a mutant exhibiting weak growth throughout development and early senescence of leaf tips, and designated this mutant weakness and leaf senescence5 (wls5). Histological analysis showed that the poor growth of wls5 plants involved a reduction in cell length and number. Physiological analysis and transmission electron microscopy revealed that the wls5 cells had abnormal chloroplasts, and the mutants underwent chlorophyll degradation triggered by accumulation of reactive oxygen species. Consistent with this, RNA sequencing revealed changes in senescence-related gene expression in wls5 plants. The wls5 mutants also exhibited significantly higher stomatal density and altered phytohormone contents compared with wild-type plants. Fine mapping delimited WLS5 to a 29-kb region on chromosome 5. DNA sequencing of wls5 identified a 3-bp deletion in the first exon of LOC_Os05g04900, resulting in a deletion of a lysine in the predicted protein. Knockout of LOC_Os05g04900 in Nipponbare plants caused leaf senescence, confirming this locus as the causal gene for WLS5.ConclusionsWe identified a novel mutant (wls5) that affects plant development and leaf senescence in rice. LOC_Os05g04900, encoding a protein of unknown function, is the causal gene for wls5. Further molecular study of WLS5 will uncover the roles of this gene in plant growth and leaf senescence.
Highlights
Results wls5 mutants exhibit weak growth in the whole plant The wls5 mutant was obtained from an ethyl methane sulfonate (EMS) mutant bank of the indica rice cultivar ‘93–11’
Senescence of plants can be induced by many factors, including reproductive growth, phytohormones, and environmental cues (Lim et al 2007); the senescence-associated genes regulated during early leaf senescence remain largely unknown
Similar to previously characterized mutants, leaf senescence in wls5 was directly related to low chlorophyll levels and high reactive oxygen species (ROS) accumulation (Fig. 3c, Fig. 4b, Fig. 5), and abnormal growth of wls5 was caused by a reduction in cell number and small cell size compared to the wild type a M1 M2
Summary
Results wls mutants exhibit weak growth in the whole plant The wls mutant was obtained from an ethyl methane sulfonate (EMS) mutant bank of the indica rice cultivar ‘93–11’. The molecular mechanisms behind these processes have been widely studied; the complex genetic regulatory networks controlling growth and senescence require further elucidation Abnormal development, such as weak growth (dwarf height and small tissues and organs) and early senescence, has major effects on rice yield (Sakamoto and Matsuoka 2008; Pan et al 2013; Liu et al 2016; Hong et al 2018). Premature leaf senescence leads to low photosynthetic efficiency and decreased accumulation of photosynthetic assimilates in reproductive organs, decreasing yield (Mitchell and Sheehy 2006; Yang et al 2016a; Mao et al 2017). Senescence of plants can be induced by many factors, including reproductive growth, phytohormones, and environmental cues (Lim et al 2007); the senescence-associated genes regulated during early leaf senescence remain largely unknown
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
