PDF(Pubmed)
Abstract：
Drought is a major factor affecting crops, thus efforts are needed to increase plant resilience to this abiotic stress. The overlapping signaling pathways between drought and cell wall integrity maintenance responses create a possibility of increasing drought resistance by modifying cell walls. Here, using herbaceous and woody plant model species, Arabidopsis and hybrid aspen, respectively, we investigated how the integrity of xylan in secondary walls affects the responses of plants to drought stress. Plants, in which secondary wall xylan integrity was reduced by expressing fungal GH10 and GH11 xylanases or by affecting genes involved in xylan backbone biosynthesis, were subjected to controlled drought while their physiological responses were continuously monitored by RGB, fluorescence, and/or hyperspectral cameras. For Arabidopsis, this was supplemented with survival test after complete water withdrawal and analyses of stomatal function and stem conductivity. All Arabidopsis xylan-impaired lines showed better survival upon complete watering withdrawal, increased stomatal density and delayed growth inhibition by moderate drought, indicating increased resilience to moderate drought associated with modified xylan integrity. Subtle differences were recorded between xylan biosynthesis mutants (irx9, irx10 and irx14) and xylanase-expressing lines. irx14 was the most drought resistant genotype, and the only genotype with increased lignin content and unaltered xylem conductivity despite its irx phenotype. Rosette growth was more affected by drought in GH11- than in GH10-expressing plants. In aspen, mild downregulation of GT43B and C genes did not affect drought responses and the transgenic plants grew better than the wild-type in drought and well-watered conditions. Both GH10 and GH11 xylanases strongly inhibited stem elongation and root growth in well-watered conditions but growth was less inhibited by drought in GH11-expressing plants than in wild-type. Overall, plants with xylan integrity impairment in secondary walls were less affected than wild-type by moderately reduced water availability but their responses also varied among genotypes and species. Thus, modifying the secondary cell wall integrity can be considered as a potential strategy for developing crops better suited to withstand water scarcity, but more research is needed to address the underlying molecular causes of this variability.
摘要：
干旱是影响农作物的主要因素,因此，需要努力提高植物对这种非生物胁迫的抵抗力。干旱和细胞壁完整性维持反应之间的重叠信号通路产生了通过修饰细胞壁来提高抗旱性的可能性。这里,使用草本植物和木本植物模型物种，拟南芥和杂交白杨，分别,我们研究了木聚糖在次生壁中的完整性如何影响植物对干旱胁迫的反应。植物,其中通过表达真菌GH10和GH11木聚糖酶或通过影响参与木聚糖骨架生物合成的基因来降低次生壁木聚糖完整性，受控制的干旱，同时通过RGB连续监测其生理反应，荧光，和/或高光谱相机。对于拟南芥，在完全取水后进行生存测试，并分析气孔功能和茎电导率。所有拟南芥木聚糖受损的品系在完全浇水后表现出更好的存活率，中度干旱增加气孔密度和延缓生长抑制，表明与改性的木聚糖完整性相关的对中度干旱的抵抗力增强。记录了木聚糖生物合成突变体（irx9，irx10和irx14）和木聚糖酶表达系之间的细微差异。irx14是最抗旱的基因型，尽管具有irx表型，但唯一具有木质素含量增加和木质部电导率不变的基因型。在GH11-表达GH10的植物中，玫瑰花结的生长受干旱的影响更大。在阿斯彭，GT43B和C基因的轻度下调不会影响干旱反应，并且在干旱和浇水条件下，转基因植物的生长比野生型更好。在水分充足的条件下，GH10和GH11木聚糖酶均强烈抑制茎的伸长和根的生长，但在表达GH11的植物中，干旱对生长的抑制作用小于野生型。总的来说,与野生型相比，次生壁木聚糖完整性受损的植物受到适度减少的水可利用性的影响较小，但它们的反应也因基因型和物种而异。因此，修改次生细胞壁完整性可以被认为是开发更适合抵御缺水的作物的潜在策略，但是需要更多的研究来解决这种变异性的潜在分子原因。
