每日植物阅读:红光信号与miRNA互作;胡杨E3泛素连接酶抗旱;草莓果实成熟调控机制

1 PLOS Genetics|

2  Plant Biotechnology Journal 胡杨E3泛素连接酶PeCHYR1作用于干旱抗性

First author: Fang He; Affiliations: Beijing Forestry University (北京林业大学): Beijing, China

Corresponding author: Xinli Xia (夏新莉)

Drought, a primary abiotic stress, seriously affects plant growth and productivity. Stomata play a vital role in regulating gas exchange and drought adaptation. However, limited knowledge exists of the molecular mechanisms underlying stomatal movement in trees. Here, PeCHYR1, a ubiquitin E3 ligase (E3泛素连接酶), was isolated from Populus euphratica(胡杨), a model of stress adaptation in forest trees. PeCHYR1 was preferentially expressed in young leaves and was significantly induced by ABA (abscisic acid) and dehydration (干燥) treatments. To study the potential biological functions of PeCHYR1, transgenic poplar 84K (Populus alba × Populus glandulosa) plants overexpressing PeCHYR1 were generated. PeCHYR1 overexpression significantly enhanced H2O2 production and reduced stomatal aperture (气孔孔径). Transgenic lines exhibited increased sensitivity to exogenous ABA and greater drought tolerance than that of WT (wild-type) controls. Moreover, up-regulation of PeCHYR1 promoted stomatal closure and decreased transpiration (蒸腾), resulting in strongly elevated WUE (water use efficiency). When exposed to drought stress, transgenic poplar maintained higher photosynthetic activity (光合活性) and biomass accumulation. Taken together, these results suggest that PeCHYR1 plays a crucial role in enhancing drought tolerance via ABA-induced stomatal closure caused by hydrogen peroxide (H2O2) production in transgenic poplar plants.

干旱是一类主要的非生物胁迫，严重影响了植物的生长和产量。气孔在调控气体交换和干旱适应中扮演重要作用。然而，对于林木中气孔运动的分子机制还了解得不多。本文从胁迫适应的模式林木胡杨中克隆到了一个E3泛素连接酶PeCHYR1基因。PeCHYR1基因优先在幼嫩的叶子的表达，并且被ABA和脱水显著诱导。为了研究PeCHYR1基因潜在的生物学功能，作者对转基因杨树84K进行了过表达PeCHYR1基因。过表达PeCHYR1基因会显著增强H2O2的产量，并减少气孔的孔径。转基因植株对外源的ABA处理更加敏感，同时抗旱性较野生型更强。此外，上调PeCHYR1基因的表达促进气孔的闭合，减少蒸腾，进而极大提升了水分利用效率。干旱胁迫下，转基因杨树会维持更高的光合活性和生物量积累。综上，在转基因植株中，PeCHYR1基因通过ABA诱导的气孔闭合增强干旱抗性。

通讯：夏新 (http://biology.bjfu.edu.cn/szdw/zrjs/jiaoshou/99077.html)

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2018年3月9日，Plant Physiology在线发表了北京农学院植物科学技术学院农业应用新技术北京市重点实验室沈元月教授课题组的题为“Polyamines Regulate Strawberry Fruit Ripening by ABA, IAA, and Ethylene”的研究论文。

多胺（PA）参与调控植物的生长发育过程，包括果实成熟等。然而，PA是否在草莓（Fragaria ananassa）（一种非跃变型模式植物）成熟过程中发挥作用仍不清楚。该研究发现，果实着色起始后精胺（Spm）比腐胺（Put）或亚精胺（Spd）的含量增加得更快。成熟果实中Spm的含量较高是由草莓S-腺苷-L-甲硫氨酸脱羧酶基因（FaSAMDC）的高转录丰度导致的，其编码产生多胺生物合成所需残基的酶。外源Spm和Spd能够促进果实着色，而外源Put和SAMDC抑制剂则抑制果实着色。转录组分析表明，上调和下调FaSAMDC的表达可分别促进和抑制果实成熟，这与一些生理参数及其相应基因转录本的变化相一致，包括果实硬度、花青素含量、糖含量、多胺含量、生长素（IAA）含量、脱落酸（ABA）含量和乙烯释放量。利用等温滴定量热技术，研究人员发现FaSAMDC也具有较高的酶活性，Kd为1.7×10^-3 M。

总结而言，多胺类，特别是Spm，以ABA主导，IAA参与以及乙烯协调的方式调控草莓果实成熟，而且FaSAMDC在草莓果实成熟过程中起着重要作用。

Figure 8. A model for PA regulation of strawberry fruit ripening through ABA, IAA and Ethylene.