Abstract
Sorghum (Sorghum bicolor L. Moench) exhibits various color changes in injured leaves in response to cutting stress. Here, we aimed to identify key genes for the light brown and dark brown color variations in tan-colored injured leaves of sorghum. For this purpose, sorghum M36001 (light brown injured leaves), Nakei-MS3B (purple), and a progeny, #7 (dark brown), from Nakei-MS3B × M36001, were used. Accumulated pigments were detected by using high-performance liquid chromatography: M36001 accumulated only apigenin in its light brown leaves; #7 accumulated both luteolin and a small amount of apigenin in its dark brown leaves, and Nakei-MS3B accumulated 3-deoxyanthocyanidins (apigeninidin and luteolinidin) in its purple leaves. Apigenin or luteolin glucoside derivatives were also accumulated, in different proportions. Differentially expressed genes before and after cutting stress were identified by using RNA sequencing (RNA-seq). Integration of our metabolic and RNA-seq analyses suggested that expression of only flavone synthase II (FNSII) led to the synthesis of apigenin in M36001, expression of both FNSII and flavonoid 3′-hydroxylase (F3′H) led to the synthesis of apigenin and luteolin in #7, and expression of both flavanone 4-reductase and F3′H led to the synthesis of 3-deoxyanthocyanidins in Nakei-MS3B. These results suggest that expression of FNSII is related to the synthesis of flavones (apigenin and luteolin) and the expression level of F3′H is related to the balance of apigenin and luteolin. Expression of FNSII and F3′H is thus associated with dark or light brown coloration in tan-colored injured leaves of sorghum.
Highlights
Apigenin was accumulated at high levels in M36001, whereas luteolin-3, 7-di-O-glucoside, and luteolin-8-C-glucoside were accumulated at high levels in #7 (Figure 3)
We considered that the flavone synthase II (FNSII) pathway was activated to synthesize flavones and that the expression level of flavonoid 3 -hydroxylase (F3 H) is associated with the balance of apigenin and luteolin, which in turn determined the dark or light brown variation in sorghums that respond to injury with tan pigmentation
We previously reported that other color variations are determined by the level of F3 H expression, which results in differences in the proportions of 3-deoxyanthocyanidins
Summary
Leaves can turn purple, red, orange, or tan (brown), or in-between colors. Gene Expression in Tan-Colored Sorghum orange (Mizuno et al, 2014); and those of M36001, JP501, JP43800, JP588, JP43764, and Greenleaf turn tan (brown; Kawahigashi et al, 2016). The tan-colored sorghums accumulate relatively high levels of flavones (apigenin and luteolin) than red/purple colored sorghums (Siame et al, 1993; Dykes et al, 2009, 2011). Colored pigments are accumulated in response to infection with the fungi Bipolaris sorghicola (Kawahigashi et al, 2011; Mizuno et al, 2012), Colletotrichum sublineolum (Snyder and Nicholson, 1990), Cochliobolus heterostrophus (Aguero et al, 2002), Sporisorium reilianum (Zuther et al, 2012) or to wounding stress (Mizuno et al, 2014). Pigment accumulation is considered to enhance resistance to pathogen infection (Hipskind et al, 1990; Snyder and Nicholson, 1990; Lo et al, 1999; Clifford, 2000; Kawahigashi et al, 2011; Zuther et al, 2012)
Sign-in/Register to view highlights & summary 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 callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
