SCARECROW gene function is required for photosynthetic development in maize

Abstract

The C 4 photosynthetic pathway is nearly always underpinned by characteristic Kranz anatomy, whereby vascular bundles are closely spaced and are often separated by only two mesophyll (M) cells (reviewed in Sedelnikova, Hughes, & Langdale, 2018). This cellular arrangement enables function of the C 4 cycle, in which CO 2 is initially fixed in the outer M cells by phosphoenolpyruvate carboxylase (PEPC) into the 4-carbon compound oxaloacetate. Although there are at least three distinct C 4 enzymatic cycles (Furbank, 2011), all involve a 4-carbon derivative of oxaloacetate being shuttled to the inner bundle-sheath (BS) cells to be decarboxylated. The CO 2 released in the BS cells is refixed by ribulose bisphosphate carboxylase/oxygenase (RuBisCO) in the Calvin-Benson (C 3) cycle. Importantly, refixation occurs in a cellular environment where local levels of CO 2 are high enough to suppress the competing oxygenation reaction and thus to prevent the energetically wasteful process of photorespiration. As compared to

SCARECROW is deployed in distinct developmental contexts during rice and maize leaf development

“…A similar phenotype is seen in maize, where Zmscr mutants fail to properly specify the endodermis (Hughes et al, 2019). Furthermore, both Arabidopsis and maize scr mutants exhibit a perturbed growth phenotype (Dhondt et al, 2010;Hughes et al, 2019;Hughes & Langdale, 2020). In contrast to these conserved functions, SCR has divergent functions in leaves, patterning bundle-sheath cells around veins in Arabidopsis (Cui et al, 2014;Wysocka-Diller et al, 2000) but regulating mesophyll cell specification and division in maize (Hughes et al, 2019).…”

A regulatory circuit involving the NADH dehydrogenase-like complex balances C4photosynthetic carbon flow and cellular redox in maize

“…qRT– PCR was carried out with Hieff UNICON® Universal Blue qPCR SYBR Master Mix (YEASEN, 11184ES08) in a final reaction volume of 20 μL. Relative expression was calculated by comparison to ZmEF1α (Hughes and Langdale, 2020) or OsACTIN , and data processed using Excel software.…”

Climate change challenges, plant science solutions

“…Much of the first decade of the project was spent developing tools in rice to enable this strategy, for example robust transformation pipelines, cell-type-specific promoters, and modular cloning technology. Ongoing research continues to characterize potential regulators of C 4 leaf anatomy and to evaluate whether manipulation in rice can modify cell-type patterning in the leaf ( Wang et al, 2013a , 2017a ; Schuler et al, 2018 ; Hughes et al, 2019 ; Hughes and Langdale, 2020 , 2022 )—but much more discovery research is needed before an anatomical prototype can be designed and engineered ( Sedelnikova et al, 2018 ). Recent work has, however, made progress toward engineering C 4 metabolic prototypes.…”