Elevated auxin biosynthesis and transport underlie high vein density in C4 leaves
Elevated auxin biosynthesis and transport underlie high vein density in C4 leaves
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DOI：
10.1073/pnas.1709171114
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发表时间：
2017-08-15
影响因子：
11.1
通讯作者：
Li, Wen-Hsiung
中科院分区：
文献类型：
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作者：
Huang, Chi-Fa;Yu, Chun-Ping;Li, Wen-Hsiung
高脉密度是C-4叶的一个独特性状，是C-3到C-4进化和C-3到C-4类作物转化的核心。我们测试的假设，在C-4叶片中的高静脉密度是由于生长素的生物合成和运输在发育中的叶片。生长素合成途径中的基因在发育中的C-4叶片中的表达上调，生长素含量高于发育中的C-3叶片。对于玉米叶（C-4）和谷壳（C-3）叶原基也有相同的观察结果。此外，生长素含量和脉密度增加拟南芥MYC 2，生长素生物合成的抑制基因的功能丧失突变体。用生长素生物合成抑制剂或生长素运输抑制剂处理导致新叶中的叶脉少得多。最后，拟南芥生长素外排转运蛋白pin 1和内流转运蛋白lax 2突变体显示减少静脉数。因此，高叶脉密度的发育需要提高生长素的生物合成和运输。
High vein density, a distinctive trait of C-4 leaves, is central to both C-3-to-C-4 evolution and conversion of C-3 to C-4-like crops. We tested the hypothesis that high vein density in C-4 leaves is due to elevated auxin biosynthesis and transport in developing leaves. Upregulation of genes in auxin biosynthesis pathways and higher auxin content were found in developing C-4 leaves compared with developing C-3 leaves. The same observation held for maize foliar (C-4) and husk (C-3) leaf primordia. Moreover, auxin content and vein density were increased in loss-of-function mutants of Arabidopsis MYC2, a suppressor of auxin biosynthesis. Treatment with an auxin biosynthesis inhibitor or an auxin transport inhibitor led to much fewer veins in new leaves. Finally, both Arabidopsis thaliana auxin efflux transporter pin1 and influx transporter lax2 mutants showed reduced vein numbers. Thus, development of high leaf vein density requires elevated auxin biosynthesis and transport.