刚刚，科学家利用WIWAM植物表型成像系统发表了题为“Integrity of xylan backbone affects plant responses to drought”的文章。WIWAM植物表型成像系统由于比利时根特大学VIB所和SMO公司联合开发，目前已经发表了近百篇文章。

木聚糖骨架的完整性影响植物对干旱的响应

干旱是影响农作物的一个主要因素，因此需要努力增加干旱植物对这种非生物胁迫的抵抗力。重叠的信号通路在干旱和细胞壁完整性维护响应之间创造了通过改变细胞壁来提高抗旱性的可能性。在这里，使用草本和木本植物模式树种， 拟南芥和杂交白杨，分别研究了木聚糖在次生细胞壁的完整性影响植物对干旱胁迫的响应。植物，通过表达真菌 GH10 和 GH11 木聚糖酶降低了次级壁的完整性或影响参与木聚糖骨架生物合成的基因，分别置于干旱控制条件，通过RGB、荧光和/或高光谱相机进持续监控生理反应。拟南芥，完全断水后辅以生存试验，分析气孔功能和茎导水性。拟南芥木聚糖损伤品系在完成时显示出更好的断水存活率，增加气孔密度、延迟中度干旱生长抑制中，表明其中度干旱的复原力增强与改良的木聚糖完整性有关。记录了细微的差异木聚糖生物合成突变体（IRX9、IRX10 和 IRX14）和木聚糖酶之间表达路径。IRX14是抗旱性最强的基因型，也是唯一的木质素含量增加而木质部电导率不变的基因型 IRX 表型。GH11-中玫瑰花结生长受干旱的影响大于GH11-中表达GH10的植物。在白杨中，GT43B和C基因轻度下调不影响干旱响应，在干旱和水源充足的条件下，转基因植物比野生型生长更好。GH10 和 GH11木聚糖酶在浇水良好的植物中强烈抑制茎伸长和根系生长。 但在表达GH11的植物中，干旱对生长的抑制比野生型要小。总体而言，次生木聚糖完整性受损的植物与野生型相比，细胞壁受到水供应量适度减少的影响较小，但反应在基因型和物种之间也有所不同。因此，修改二级细胞壁的完整性可以被认为是一种潜在的策略开发更适合抵御缺水的作物，但更多的研究是需要解决这种变异性的根本分子原因。

关键字

葡萄糖醛酸木聚糖， 干旱胁迫， 拟南芥， 杨树， 次生细胞壁，高光谱成像、高通量表型分析、细胞壁完整性

Integrity of xylan backbone affects plant responses to drought

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 xylanaseexpressing 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.

KEYWORDS

glucuronoxylan, drought stress, Arabidopsis, Populus, secondary cell wall, hyperspectral imaging, high-throughput phenotyping, cell wall integrity