RedundantSCARECROWgenes pattern distinct cell layers in roots and leaves of maize

Abstract

16 17 Summary statement: Two duplicated maize SCARECROW genes control the development of the 18 endodermis in roots and the mesophyll in leaves 19 2 ABSTRACT 20 The highly efficient C4 photosynthetic pathway is facilitated by 'Kranz' leaf anatomy. In Kranz leaves, 21 closely spaced veins are encircled by concentric layers of photosynthetic bundle sheath (inner) and 22 65 recruited in the leaf rather than the root in maize, but the subtle phenotype reported in leaves of 66 Zmscr1 mutants precludes an understanding of the precise role played during Kranz development. 67 68 Both gene and whole genome duplication events are highly prevalent throughout the plant phylogeny 69 (Adams and Wendel, 2005; Blanc and Wolfe, 2004) and if retained in the genome, duplicated genes 70 are free to sub-or neo-functionalize (Moore and Purugganan, 2005; Ohno, 1970). Perhaps more 71 553 Adams, K. L. and Wendel, J. F. (2005). Polyploidy and genome evolution in plants. Curr. Opin.

On the road to C4 rice: advances and perspectives

“…Because BS cell size does not differ substantially between C 3 and C 4 grass species (Figure , Danila et al , ), reducing the interveinal distance appears to be the most logical path to increase S b in rice. Ideally, this would mean upregulation of gene(s) that would promote insertion of additional veins between existing veins of rice, thus reducing interveinal distance and, at the same time, decreasing the number of M cells between veins (Sedelnikova et al , ; Hughes et al , ).…”

SCARECROW gene function is required for photosynthetic development in maize

“…In contrast, both Zmscr1‐m2;Zmscr1h‐m1 and Zmscr1‐m2;Zmscr1h‐m2 mutants (hereafter referred to as the m2m1 and m2m2 lines for simplicity) had significantly lower levels of total chlorophyll than WT on a leaf area basis (Figure 1a). To ensure that this difference was not indirectly caused by a reduction in leaf thickness, the thickness of leaves was quantified in both double mutants (Hughes et al., 2019). A slight mean reduction in the thickness of the m2m1 leaves was observed, although it was smaller in magnitude and less consistent than the chlorophyll reduction, and there was no change in the m2m2 line (Figure ).…”

“…Both Zmscr1‐m2;Zmscr1h‐m1 ( m2m1 ) and Zmscr1‐m2;Zmscr1h‐m2 ( m2m2 ) double mutants were generated and described previously (Hughes et al., 2019). As segregating wild‐type lines for both were indistinguishable, the WT ( m2m1 ) line was chosen for comparison of both lines in this study.…”

“…Developmental regulators of Kranz anatomy have proved elusive; however, it was recently reported that the duplicated maize SCARECROW (SCR) genes ZmSCR1 and ZmSCR1h redundantly regulate Kranz patterning (Hughes, Sedelnikova, Wu, Becraft, & Langdale, 2019). In Zmscr1;Zmscr1h mutants, the majority of vascular bundles are separated by only one rather than two mesophyll cells, and there are additional patterning perturbations in both leaves and roots (Hughes et al., 2019).…”

Form, development and function of grass stomata

“…Accordingly, osscr1 osscr2 double‐mutants show reduced stomatal density and morphological defects during stomatal development in rice (Wu et al , ). This suggests that the grass SHR/SCR module not only controls vein development and Kranz anatomy in the C 4 grass maize (Slewinski et al , ; Hughes et al , ), but also patterning and development of stomata in rice (Kamiya et al , ; Schuler et al , ; Wu et al , ). Usually, grasses form between one and two (sometimes three) adjacent stomatal rows depending on the species, the kind of leaf and, potentially, environmental factors (Stebbins and Shah, ).…”